Fabrication and mechanical performance of bark cloth/glass fiber reinforced hybrid polymer composites for automotive applications

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Composites were fabricated using the hand layup technique with varying fiber weight fractions (15%, 20%, and 25%) and hybrid ratios (3:1, 2:2, 1:3). The influence of hybrid ratio and stacking sequence on flexural, tensile, compressive, and impact strengths was evaluated. Results indicated that composites with higher glass fiber content exhibited superior mechanical performance, with optimal flexural (140.94 MPa), tensile (43.24 MPa), compressive (26.47 MPa), and impact strengths (32.44 kJ/m²) at a 1:3 hybrid ratio. Hybridization improved the mechanical properties of the composites, particularly flexural strength, which was significantly affected by stacking sequence. These findings suggest that bark cloth/glass fiber hybrid composites have potential for applications in automotive and structural industries. Materials Engineering Bark cloth Glass fiber Hybrid composites Polyester resin Mechanical properties Stacking sequence Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction Bark cloth is a unique, non-woven fibrous textile produced from the bark of various tree species, with Ficus natalensis being the primary species used in Uganda. Locally known as "mutuba," this tree grows naturally in Uganda's tropical climate and requires minimal care, as it thrives without the need for fertilizers. Ficus natalensis , along with other species such as Antiaris toxicaria and Ficus brachypoda , is particularly valued for its renewable nature. The bark of the tree can be harvested annually without felling the tree, making it a sustainable resource 1 , 2 . A single tree can continue to produce bark cloth for over 30 years, with the bark regenerating after each harvest 3 . The production of bark cloth involves stripping the bark from the tree, which is then processed through steaming and beating with carved wooden hammers. This traditional method, passed down through generations, stretches the fibers and creates the distinctive terracotta-colored cloth. The cloth holds cultural significance in Uganda, being used for royal garments, religious ceremonies, and funerals 4 . The importance of bark cloth to Ugandan culture led UNESCO to recognize it as a "Masterpiece of the Intangible Cultural Heritage of Humanity," emphasizing the need to protect the knowledge and traditions surrounding its production 2 . In addition to its cultural value, bark cloth has gained attention for its potential as a reinforcement material in composite applications. Studies have shown that bark cloth consists of cellulosic microfibers aligned at 45° angles, providing moderate tensile properties. Scanning Electron Microscopy (SEM) analysis revealed that the fibers are oval-shaped and bonded by lignin and hemicelluloses, with diameters ranging between 10 and 20 µm 5 . The strength of bark cloth was measured at 101.7 N longitudinally and 23.5 N transversely, with a fabric thickness of approximately 1.084 mm 5 . These properties, along with its thermal stability below 200°C, suggest that bark cloth can be used for composite reinforcement, particularly in applications where lightweight and biodegradable materials are desirable 6 – 10 . Despite its potential due to its sustainability, low density, and cost-effectiveness, the key challenges in using bark cloth and other natural fibers for structural applications, particularly in the automotive industry, is their durability. Natural fibers have a high affinity for moisture due to their hydrophilic nature, which can lead to water absorption and subsequently reduced mechanical performance over time. For example, prolonged exposure to moisture can cause swelling, fiber debonding, and degradation of fiber-matrix adhesion, leading to a significant reduction in properties such as tensile and flexural strength. In addition, they generally exhibit lower mechanical properties than synthetic fibers, such as glass and carbon fiber, which limits their use in high-performance applications 11 – 14 . To address these limitations, researchers have explored hybrid composites that combine natural fibers with synthetic fibers. Hybrid composites leverage the sustainability of natural fibers while benefiting from the mechanical strength of synthetic fibers. This combination offers improved mechanical performance, including tensile, flexural, and impact strengths 14 , 15 . Recent studies have shown that treatments or hybridization with synthetic fibers, such as glass, can mitigate these effects by reducing moisture absorption and improving long-term stability 16 – 19 , 19 – 25 . For example, Santhanam et al. 26 reported significant improvements in tensile and flexural strength when glass fibers were added to banana fiber/polyester composites. Similarly, Selver et al. 27 demonstrated that hybrid composites made from jute and glass fibers showed enhanced mechanical properties compared to pure natural fiber composites. Sanjay et al. 28 reviewed the mechanical properties of natural fiber polymer composites, emphasizing that water absorption is a major factor affecting their long-term durability. The review suggests that hybridizing natural fibers with synthetic fibers or applying surface treatments can significantly mitigate these durability issues, improving the composites' resistance to environmental degradation. Another important aspect of improving natural fiber composites is enhancing their mechanical and moisture-resistant properties by hybridization. Sanjay et al. 29 discussed how hybridizing lignocellulosic fibers with synthetic fibers, such as glass, leads to composites that demonstrate improved mechanical properties and better resistance to moisture and environmental stresses. The incorporation of synthetic fibers into natural fiber composites not only improves their structural performance but also increases their applicability in sectors such as automotive and construction, where environmental resistance is critical 30 , 31 . Our study builds upon these findings by investigating the mechanical performance of hybrid composites made from bark cloth and E-glass fibers, with an emphasis on their potential for automotive applications. The hybridization of natural fibers with E-glass fibers offers several significant advantages in composite materials, particularly for applications requiring high performance and sustainability 32 , 33 . Natural fibers, such as coconut leaf sheath, jute, and sisal, are lightweight and biodegradable, contributing to both weight reduction and environmental sustainability. However, their mechanical properties are often lower compared to synthetic fibers like E-glass. Studies by Bharath et al. 34 and Arpitha et al. 35 show that the combination of these natural fibers with E-glass fibers significantly enhances tensile and flexural strength, making the resulting hybrid composites suitable for structural and automotive applications. The hybridization also provides cost benefits, as natural fibers are more affordable than synthetic materials. Moreover, the addition of E-glass fibers improves the durability and resistance to moisture of the composites, addressing the common limitation of natural fibers in harsh environmental conditions. This balance of enhanced mechanical performance, cost-effectiveness, and sustainability makes hybrid composites highly attractive for a variety of industrial uses. The automotive industry, in particular, has shown great interest in hybrid composites due to their potential to reduce vehicle weight while maintaining strength and durability. The use of natural fibers in automotive components can reduce both material costs and environmental impact 11 , 12 . For example 36 , highlighted the role of natural fiber composites in the production of non-structural parts, while a number of studies have emphasized their potential to replace traditional materials such as aluminum and glass fibers in specific applications 37 – 39 . Hybrid composites, with their tailored mechanical properties, offer the versatility needed for a wide range of applications in automotive, construction, and other industries 26 , 27 , 40 . The mechanical properties of hybrid composites depend on several factors, including fiber weight fraction, hybrid ratio (the proportion of natural to synthetic fibers), and stacking sequence (the arrangement of fibers within the composite) 41 , 42 . Studies have shown that increasing the glass fiber content improves the mechanical properties of hybrid composites 43 – 45 . These studies reported that the tensile and flexural strength of hybrid composites increased with higher glass fiber content, while excessive natural fiber content led to poor fiber-matrix adhesion 46 , 47 Additionally, the stacking sequence of fibers plays a critical role in determining the composite's mechanical properties 48 – 51 . For example, Sanjay et al. 40 found that placing glass fibers in the outer layers of hybrid composites significantly improved flexural strength compared to composites with natural fibers on the surface. Research has demonstrated the effectiveness of hybridization in improving the mechanical properties of composites. For instance, Santhanam et al. 26 found that hybrid composites with glass and natural fibers exhibit superior flexural and tensile properties. Other studies have confirmed the benefits of hybridization, including Dalbehera et al. 52 who observed improved impact strength and stiffness in jute/glass hybrid composites. Moreover, Altaee et al. 53 reported that hybrid composites with glass fibers in the outer layers and natural fibers in the core can offer optimal mechanical performance for specific applications, such as load-bearing and structural components. Despite extensive research on hybrid composites using fibers such as jute, flax, and sisal, studies on bark cloth hybrid composites are still limited. However, recent research has shown that bark fibers from other plants, such as Ficus carica and Prosopis juliflora , possess desirable properties for composite reinforcement, including high cellulose content and thermal stability 9 , 10 . These findings suggest that bark cloth has the potential to be an effective reinforcement material when hybridized with synthetic fibers. This study aims to fill the research gap by investigating the mechanical properties of bark cloth ( Ficus natalensis ) and glass fiber hybrid composites. Specifically, it focuses on the effects of fiber weight fraction, hybrid ratio, and stacking sequence on flexural, tensile, compressive, and impact strengths. The study seeks to optimize these parameters to enhance the performance of bark cloth-based hybrid composites, making them suitable for use in automotive, construction, and other industrial applications where sustainability and strength are key requirements. Materials and Method Materials The materials used in this study include bark cloth, harvested from Ficus natalensis trees in Mukoko village, Masaka district, Uganda, and commercially available glass fabric (Fig. 1 ). Unsaturated polyester resin, with a density of 1.12 g/cm³, was used as the matrix, combined with methyl ethyl ketone peroxide (MEKP) catalyst in a ratio of 100:1 by weight. The glass fiber mat and resin were procured from Narkhi Enterprises Limited in Nairobi, Kenya. The characteristics of glass fiber and the unsaturated polyester resin is presented in Table 1 . Table 1 Characteristics of glass fibers and unsaturated polyester resin Properties Glass fibers Polyester resin Appearance - Opaque Viscosity - 4–5 Water absorption (%) (7 day value) - 0.4 Heat distortion temperature (◦C) - 63.1 Elongation at break (%) 3.1–4.8 2.9 Bending Strength (kgf/mm 2 ) - 8.1 Bending Modulus (kgf/mm 2 ) - 523.3 Tensile Strength (kgf/mm 2 ) 203.94–356.90 2.8 Impact Strength (kgf-cm/cm) - 3.6 Density (g/cm3) 2.5–2.7 1.12 Toughness (MJ/m 3 ) 40–50 - Tensile modulus (GPa) 70–76 - Fiber diameter (µm) 11–12 - Moisture Content (%) 0.15 - Bark Cloth and Glass fabric Characterization The characterization of bark cloth and glass fiber mat (also known as non-woven glass fabric) was conducted to determine their thickness, areal density, and tensile strength (Table 2 ). The thickness was measured using a digital thickness gauge under a pressure of 1 kPa, with the average thickness of five specimens recorded. Areal density was determined by cutting samples into 0.1 x 0.1 m squares and weighing them with an electronic balance, following ASTM D6242-98. Tensile strength was tested in both the longitudinal and transverse directions according to ASTM D5035-95 (Strip Method), using a Universal Testing Machine. The glass fiber mat’s areal density and fiber length were also characterized, with fiber length measured based on ISO 6989:1981 standards. Table 2 Properties of bark cloth and non-woven glass fabric Properties Bark Glass Fabric type Non-woven Non-woven Composition 100% bark 100% E-glass Fabric thickness (mm) 1.45 - Areal density (gsm) 385.80 394.00 Longitudinal tensile strength (MPa) 6.30 - Transverse tensile strength (MPa) 0.26 - Fibre length (mm) - 45.68 Composite Fabrication The composites were fabricated using the hand layup technique in a steel mold measuring 300 mm x 300 mm x 20 mm, with a polished lid. Bark cloth and glass fiber mats were cut according to the mold dimensions as depicted in Fig. 2 . The polyester resin, catalyzed with methyl ethyl ketone peroxide (MEKP), was used as the matrix material. The fabrication process involved laying the first reinforcement layer into the mold, followed by resin application and consolidation with a roller to eliminate air voids. Subsequent layers were applied to achieve the desired hybrid structure, varying the stacking sequence and fiber weight fractions. Four layers of reinforcement were used. A consolidation pressure of 3.57 kN/m² was applied, and the composites were cured at room temperature for 7 hours before demolding. In this study, various composite samples were prepared by varying two key factors: fiber weight fraction and the hybrid ratio of bark cloth to glass fiber. The experiments were designed to assess how these variations affect the mechanical properties of the hybrid composites. The fiber weight fraction was set at 15%, 20%, and 25%, while the hybrid ratio of bark cloth to glass fiber ranged from 3:1, 2:2, 1:3. Two control composites with bark cloth to glass fiber ratio of 4:0 and 0:4 respectively, were also fabricated. Ten types of composite samples were produced, as outlined in Table 3 . These samples were fabricated by adjusting both the fiber weight fraction and the reinforcement stacking sequence. The samples included controls with either 100% bark cloth or 100% glass fiber. The hybrid composites consisted of varying combinations of bark cloth and glass fiber, arranged in different stacking sequences. By varying the fiber weight fraction and hybrid ratio, a comprehensive analysis of how these factors influence the mechanical behavior of bark cloth/glass fiber hybrid composites was achieved. Table 1 Experimental design for producing the different composite sample types Composite sample types Fibre weight fraction (%) Weight of fibres (g) Resin weight (g) Catalyst weight (g) Composite designation Reinforcement stacking sequence 1 15 92.7 520.1 5.2 3B1 B-B-G-B 2 25 107.8 320.2 3.2 3B2 B-B-G-B 3 15 134.6 755.1 7.6 3G1 G-G-B-G 4 25 138.0 409.9 4.1 3G2 G-G-B-G 5 20 88.2 349.3 3.5 B B-B-B-B 6 20 159.2 630.5 6.3 G G-G-G-G 7 20 104.0 411.9 4.1 BG1 B-G-B-G 8 20 109.0 431.7 4.3 BG2 B-G-G-B 9 20 113.1 447.9 4.5 BG3 G-B-B-G 10 20 132.5 524.8 5.2 BG4 B-B-G-G Mechanical Testing Composite samples were prepared and cut in accordance with ASTM and ISO standards to ensure uniformity across all tests. Prior to testing, the specimens were conditioned in the laboratory for 48 hours at a temperature of 23 ± 2°C and relative humidity of 65%, which ensured that the mechanical properties were assessed under controlled conditions. This helped to minimize the effects of moisture and temperature variations on the results. The flexural strength of the composites was determined following ASTM D790. The test was conducted using a computer-controlled Testomeric machine (Model M/C S/No: 500-10171) with a 24.5 kN capacity, operating at a crosshead speed of 10 mm/min. The span length was calculated as 16 times the specimen thickness, and the specimen width was one-quarter of the span length, with an additional 25 mm overhanging allowance on both ends. The test involved applying a load at the center of the specimen until failure occurred, with five specimens tested for each composite type. Flexural strength is a crucial property for determining a material's resistance to bending, particularly in applications such as automotive and structural components. Tensile strength tests were conducted in accordance with ASTM D3039, using a Universal Testing Machine (Model UT-10; S/No: 2015/12) with a 100 kN capacity at a crosshead speed of 5 mm/min. The specimens had dimensions of 300 mm in length, 25 mm in width, and a gauge length of 200 mm. Tensile strength is important for assessing the material’s resistance to tension and stretching forces, which is relevant for applications where the composites will undergo pulling or stretching stresses. Compressive strength tests were performed following ASTM D3410M, also using the Universal Testing Machine (Model UT-10; S/No: 2015/12) with a 100 kN capacity at a crosshead speed of 5 mm/min. Specimens were prepared with a length of 40 mm, a width of 25 mm, and a gauge length of 40 mm. This test measures the composite’s ability to withstand compressive forces and eliminates the possibility of buckling, which is critical for evaluating the performance of the composites in load-bearing applications. Impact strength was measured using an impact tester (Model HLE; S/No: 2015/15) according to ISO 179-1:2000 standards. The impact test was conducted with a 15 J hammer, and the specimens had a length of 60 mm, a width of 10 mm, and a span length of 40 mm. All the specimens were un-notched to evaluate their natural resistance to impact. Impact strength is an essential measure of a material’s ability to absorb energy and resist sudden forces, which is especially important for safety-critical applications such as in the automotive industry. For all mechanical tests, five specimens were tested for each composite type, and the average values were reported. These mechanical tests are vital for understanding the overall performance of the hybrid composites and determining their potential for use in various engineering applications. Statistical Analysis The experimental data obtained from the mechanical tests were statistically analyzed to determine the significance of the effects of fiber weight fraction and hybrid ratio on the mechanical properties of the composites. One-way Analysis of Variance (ANOVA) was used to assess the significance of differences in the flexural, tensile, compressive, and impact strengths of the various composite samples. The ANOVA was performed at a 95% confidence level, with a p-value of less than 0.05 considered statistically significant. The F-values and p-values were reported for each mechanical property to quantify the influence of the composite parameters. This statistical analysis provided a robust evaluation of the experimental results, identifying which factors had a significant effect on the performance of the bark cloth/glass fiber hybrid composites. SEM Analysis The Scanning Electron Microscopy (SEM) analysis was performed to investigate the surface morphology and cross-sectional structure of hybrid composites with various stacking sequences of bark cloth (B) and glass fibers (G). The samples were prepared with sequences G-G-B-G, B-G-B-G, and B-G-G-B. Small sections were cut from each composite for analysis. SEM images were taken using a VEGA3 TESCAN SEM at an accelerating voltage of 5.0 kV, with magnifications set at 250x for surface analysis and 2.00kx for cross-sectional analysis. The images provided insights into fiber pull-out, microvoids, and the fiber-matrix interaction, highlighting areas of poor resin impregnation and bonding. This methodology enabled a detailed assessment of the structural integrity and mechanical behavior of the composites. Results and Discussion The mechanical properties of the bark cloth and glass fabric hybrid composites were analyzed based on flexural, tensile, compressive, and impact strength tests. The effects of varying fiber weight fractions and hybrid ratios (bark cloth to glass fabric) on these properties were investigated to evaluate the performance of the composites. Composite thickness ranged from 4.0 mm to 5 mm. Figure 3 depicts the failed composites after undergoing the necessary named tests. As seen, most composites failed within acceptable levels. Flexural Strength The flexural strength of the bark cloth and glass fiber hybrid composites was significantly influenced by the hybrid ratio and fiber weight fractions of 15%, 20%, and 25%, as shown in Figs. 4 . Composites with a higher proportion of glass fiber consistently exhibited superior flexural performance compared to those with a higher proportion of bark cloth. These results align with previous research, which also observed that synthetic fibers like glass provide enhanced mechanical reinforcement in hybrid composites. For instance, Hanifawati et al. 46 reported a notable improvement in tensile and flexural strength when glass fiber was added to a banana fiber/polyester matrix. Similarly, Bindal et al. 47 demonstrated that hybrid composites made from natural and synthetic fibers, such as jute/glass, exhibited improved flexural properties compared to pure natural fiber composites. At 20% fiber weight fraction, composites showed better overall flexural performance than the 25% fiber weight fraction composites, but they were still slightly inferior to the 15% weight fraction composites, suggesting that 20% provides a balanced performance when fiber content and resin wetting are optimized. The observed poor performance at 25% fiber weight fraction is likely due to insufficient resin for fiber wetting, leading to poor fiber-matrix adhesion. Studies like Shahzad et al. 54 corroborate this observation, reporting that fiber agglomeration at higher content can lead to a decrease in mechanical properties due to inefficient load transfer between fibers. Additionally, Rachchh et al. 55 found that increasing the natural fiber content beyond optimal levels in glass/natural fiber composites leads to decreased tensile and flexural strength, further supporting our results. The ANOVA results (Table 4 ) for flexural strength indicated significant differences across hybrid ratios at all fiber weight fractions (15%, 20%, and 25%), with p-values lower than 0.05. The 20% fiber weight fraction composites showed improved performance compared to the 25% composites, likely due to better fiber distribution and resin penetration. Table 4 Analysis of variance for effect of hybrid ratio on bark cloth and glass fabric reinforced polyester composites Mechanical Property Fiber weight fraction Source of Variation SS df MS F-value P-value Flexural strength 15% Between Groups 15335.84 1 15335.84 42.50619 0.000184 Within Groups 2886.326 8 360.7908 Total 18222.17 9 20% Between Groups 100503.2 5 20100.63 14.54638 1.34E-06 Within Groups 33163.92 24 1381.83 Total 133667.1 29 25% Between Groups 16341.81 1 16341.81 70.74337 3.04E-05 Within Groups 1848.01 8 231.0012 Total 18189.82 9 Tensile strength 15% Between Groups 870.1158 1 870.1158 35.66891 0.000334 Within Groups 195.1539 8 24.39424 Total 1065.27 9 20% Between Groups 3329.748 5 665.9497 60.79107 7.7E-13 Within Groups 262.9135 24 10.95473 Total 3592.662 29 25% Between Groups 841.6228 1 841.6228 131.7509 3.01E-06 Within Groups 51.10388 8 6.387985 Total 892.7266 9 Compressive strength 15% Between Groups 60.12304 1 60.12304 0.496407 0.501076 Within Groups 968.9316 8 121.1165 Total 1029.055 9 20% Between Groups 3847.087 5 769.4174 10.87158 1.5E-05 Within Groups 1698.559 24 70.77329 Total 5545.646 29 25% Between Groups 290.8445 1 290.8445 45.23302 0.000149 Within Groups 51.43932 8 6.429915 Total 342.2838 9 Impact strength 15% Between Groups 5.21284 1 5.21284 0.387706 0.55084 Within Groups 107.5627 8 13.44534 Total 112.7756 9 20% Between Groups 398.1756 5 79.63512 8.52665 9.43E-05 Within Groups 224.1493 24 9.339555 Total 622.3249 29 25% Between Groups 23.13441 1 23.13441 1.398344 0.270952 Within Groups 132.3532 8 16.54415 Total 155.4876 9 Tensile Strength Tensile strength results mirrored the flexural strength trend, with higher glass fiber content improving the tensile strength of the hybrid composites (Fig. 4 ). This is consistent with findings from Misri et al. 56 , who reported that the inclusion of glass fiber in sugar palm composites increased tensile strength by 59.20%. The highest tensile strength was observed at 15% fiber weight fraction, while the 20% fiber weight fraction composites performed better than those with 25%. The superior tensile performance at 15% can be attributed to better resin penetration and more uniform fiber distribution. Composites with a 1:3 hybrid ratio and glass fibers in higher proportion, such as composite BG3, exhibited the best tensile performance at 20% fiber weight fraction due to improved load transfer from the glass fibers. Similar observations were made by Hemalatha et al. 57 , who found that hybrid composites with higher synthetic fiber content, such as jute/glass composites, showed enhanced tensile performance due to better load transfer and fiber-matrix adhesion. In contrast, the 25% fiber weight fraction composites, such as 3B2 (B-B-G-B), exhibited reduced tensile strength, which could be attributed to insufficient resin and poor wetting of the fibers. According to Kumar et al. 58 , higher natural fiber content increases matrix absorption, reducing resin availability for fiber wetting, which is a critical factor in tensile performance. The ANOVA results (Table 4 ) for tensile strength at all fiber weight fractions (15%, 20%, and 25%) showed statistically significant differences (p < 0.05), confirming that the hybrid ratio and fiber content played a crucial role in determining the tensile behavior of the composites. Compressive Strength The compressive strength tests revealed that hybrid composites with higher glass fiber content exhibited superior performance (Fig. 4 ), which aligns with the findings of Misri et al. 56 , who reported that glass fibers provide superior resistance to compressive forces in hybrid composites. The 1:3 hybrid ratio composites showed the highest compressive strength at both 15% and 20% fiber weight fractions, with the latter providing a balanced performance. Composites with a 20% fiber weight fraction outperformed those with 25%, likely due to fewer agglomeration issues and better resin penetration. At 25% fiber weight fraction, composites suffered from reduced compressive strength due to inadequate resin distribution and fiber agglomeration, which hindered uniform load distribution. The reduction in compressive strength at 25% fiber weight fraction can be attributed to fiber agglomeration and poor fiber-matrix adhesion, as observed in previous studies 54 . In glass/natural fiber hybrid composites, Rachchh et al. 55 reported that exceeding an optimal natural fiber content led to reduced compressive strength due to uneven fiber distribution and resin starvation. The ANOVA results (Table 4 ) for compressive strength indicated significant differences at both 20% and 25% fiber weight fractions, with p-values below 0.05, confirming the importance of hybrid ratio and fiber content in determining compressive performance. Impact Strength The impact strength of the hybrid composites increased with the inclusion of glass fibers, consistent with findings from Kumar 59 , who noted that good fiber-matrix adhesion improves impact resistance. At 20% fiber weight fraction, composite BG4 (B-B-G-G) exhibited the highest impact strength of 27.50 kJ/m², surpassing the performance of 25% composites. The presence of glass fibers in the outer layers facilitated effective load transfer during impact, allowing the composite to absorb and dissipate energy more efficiently. Similar trends were reported by Mohanta et al. 60 , where hybrid composites with synthetic fibers in the outer layers showed superior impact resistance compared to natural fiber composites. The impact performance of the 25% fiber weight fraction composites was lower due to fiber agglomeration and insufficient resin penetration, as noted by Shahzad et al. 54 , and Rachchh et al. 55 . At 20% fiber weight fraction, hybrid composite BG4 (B-B-G-G) exhibited the highest impact strength of 27.50 kJ/m² (Fig. 5 ), outperforming the 25% composites but slightly underperforming compared to the 15% composites. The presence of glass fibers in the outer layers facilitated effective load transfer during impact, resulting in better energy absorption and distribution. This improvement in impact resistance is similar to the findings of Kumar 59 , where good fiber-matrix adhesion improved impact strength. The ANOVA results (Table 4 ) for impact strength at 20% fiber weight fraction revealed significant differences (p < 0.05), confirming that hybridization and fiber arrangement contributed to the improved impact resistance of the composites. The 20% composites performed better than the 25% composites due to better fiber-matrix bonding and fewer fiber agglomeration issues. Effect of stacking sequence The stacking sequence had a profound impact on the mechanical performance of the hybrid composites, particularly at 20% fiber weight fraction. As seen in Fig. 6 , composites with glass fibers in the outer layers exhibited higher mechanical properties across flexural, tensile, and compressive strengths. The importance of the stacking sequence in enhancing the mechanical properties of natural fiber-based composites has been reported in previous studies 40 , 48 . In this study, composite BG3 (G-B-B-G) at 20% fiber weight fraction showed the best tensile strength, which can be attributed to the advantageous placement of glass fibers in the outer layers, improving load distribution. Similarly, composite BG4 (B-B-G-G) exhibited the highest impact strength (Fig. 7 ), benefiting from the glass fibers on the outer side, which facilitated effective load transfer during impact. At 20% fiber weight fraction, the stacking sequence played a crucial role in optimizing the balance between the rigidity provided by glass fibers and the flexibility and sustainability of bark cloth. The 20% composites outperformed the 25% composites due to better fiber distribution and fewer agglomeration issues. When glass fibers were placed as the outer layers, as in BG3 and BG4, the composites showed significant improvements in mechanical performance compared to configurations where bark cloth was in the outer layers, such as B-G-G-B. The results also showed that hybrid composites with alternating layers of bark cloth and glass fiber outperformed pure bark cloth composites in all mechanical properties. For instance, the flexural strength of hybrid composites increased by 137.98%, tensile strength by 81.59%, and compressive strength by 51.58% compared to pure bark cloth composites. These findings align with studies such as Santhanam et al. 26 , which found that stacking sequence had a more substantial effect on flexural and impact strength than tensile strength. The ANOVA results (Table 4 ) for the effect of stacking sequence on flexural, tensile, compressive, and impact strengths at 20% fiber weight fraction confirmed significant differences (p < 0.05). The F-ratio values were higher than the F-criteria values, indicating that the stacking sequence significantly affected the performance of the composites. The highest mechanical properties were consistently observed in composites with glass fibers in the outer layers, such as BG3 and BG4. Surface Morphology and Cross-Section Analysis The SEM analysis of the B-G-G-B hybrid composite highlights both surface and cross-sectional features that provide insights into the material's structure and performance. In the surface morphology at 250x magnification (Fig. 8 a), roughness and fiber pull-out are visible, indicating regions of incomplete resin impregnation. These voids and surface irregularities suggest that the bonding between the matrix and fibers, especially in the bark cloth layers, may not be sufficient, which could lead to stress concentration points and reduced mechanical integrity. In the cross-sectional view at 2.00kx magnification (Fig. 8 b), the glass fiber layers are well integrated, showing a more uniform bond with the matrix. However, the bark cloth layers exhibit fiber pull-out and weaker bonding, with voids observed between the fibers and the matrix. This indicates potential flaws in the resin impregnation process, particularly in the natural fiber regions. These imperfections could act as points of failure under mechanical stress, compromising the overall durability of the composite 50 . For the B-G-B-G hybrid composite, the SEM analysis also reveals rough surface morphology (Fig. 8 c), with significant fiber pull-out and voids, again suggesting incomplete resin impregnation. The bark cloth fibers show weaker bonding compared to the glass fibers. In the cross-section (Fig. 8 d), glass fibers appear more consistently bonded to the matrix, while the bark cloth layers are less integrated, with visible fiber pull-out and voids that could reduce mechanical strength. Finally, for the G-G-B-G hybrid composite, surface analysis shows a similar roughness, with some regions exhibiting fiber pull-out (Fig. 8 e). In the cross-section (Fig. 8 f), the glass fibers are well embedded, but the bark cloth layers show weaker bonding and void formation, indicating potential weaknesses in fiber-matrix adhesion. These defects highlight the need for improved resin infiltration and fiber alignment to enhance the composite's overall structural integrity and mechanical performance. Conclusion This study demonstrated that hybridizing bark cloth with glass fibers significantly enhances the mechanical properties of polyester composites, particularly in terms of flexural, tensile, compressive, and impact strengths. Composites with higher glass fiber content exhibited superior performance, especially when glass fibers were positioned on the outer layers. The 15% and 20% fiber weight fractions produced better mechanical properties due to improved resin wetting and reduced fiber agglomeration, while the 25% fiber weight fraction composites showed weaker performance due to insufficient resin and fiber clumping. The stacking sequence also played a critical role, with alternating layers of bark cloth and glass fibers showing enhanced load distribution and energy absorption. The 1:3 hybrid ratio (glass to bark cloth) and 20% fiber weight fraction provided an optimal balance between material efficiency and mechanical performance. Statistical analysis confirmed that the hybrid ratio, fiber weight fraction, and stacking sequence significantly influenced the composites' mechanical properties. The SEM analysis revealed that incomplete resin impregnation and the presence of microvoids, particularly in the bark cloth layers, contributed to fiber pull-out and weaker fiber-matrix bonding, highlighting the need for optimized resin infiltration and fiber alignment to improve the composite’s mechanical performance and durability Further, it is recommended to explore different natural fibers and hybrid ratios to further optimize performance, investigate resin formulations or surface treatments to improve fiber-matrix adhesion, especially at higher fiber content, and evaluate the composites' long-term durability and environmental resistance in real-world applications. These improvements could expand the use of hybrid composites in various structural and load-bearing applications, promoting sustainability without compromising performance. Declarations Conflicts of Interest The authors declare that there are no conflicts of interest regarding publication of this paper. Acknowledgements The authors are grateful to the Management of Moi University-Kenya, Multimedia University-Kenya, and Busitema University-Uganda where the tests were carried out from. Frances Alibet is grateful to the World Bank for the scholarship awarded to her through the Africa Centre of Excellence II in Phytochemicals, Textiles and Renewable Energy (ACE II PTRE-Credit no. 5798-KE ) at Moi University-Kenya. Data Availability Data available within the manuscript. Author Contribution Statement Frances Alibet: conceptualization, methodology, investigation, formal analysis, data curation, writing—original draft, and writing—review and editing. Paul Wambua: resources, writing—review and editing, supervision, and funding acquisition. David Njuguna Githinji: resources, validation, writing—review and editing, supervision, and funding acquisition. Samson Rwahwire: resources, validation, writing—review and editing, supervision, and funding acquisition. Ocident Bongomin: writing and editing the revised manuscript, methodology, visualization, writing—review and editing, validation, and formal analysis. References Venkatraman P, Scott K (2018) Investigation of bark cloth for its surface texture and durability for apparel applications. The 91st Textile Institute World Conference, 23 July –26 July 2018, Leeds, UK 1–16 (2018) Rwawiire S, Tomkova B (2014) Thermo-physiological and comfort properties of Ugandan barkcloth from Ficus natalensis. J Text Inst 105:648–653 Nakirulu E, BARK CLOTH (2013) Swedish consumer attitudes towards sustainable fabrics. Fac Swed School Textiles Univ Boras Worden S (2016) Tradition and Transition: The changing fortunes of barkcloth in Uganda. Textile Society of America Symposium Proceedings. 1012 596–606 Rwawiire S, Luggya GW, Tomkova B, Morphology (2013) Thermal, and Mechanical Characterization of Bark Cloth from Ficus natalensis. ISRN Textiles 1–8 (2013) Queiroz HFM, De, Banea MD, Cavalcanti DK (2021) K. Adhesively bonded joints of jute, glass and hybrid jute / glass fibre reinforced polymer composites for automotive industry. Appl Adhes Sci. 10.1186/s40563-020-00131-6 Peças P, Carvalho H, Salman H, Leite M (2018) Natural Fibre Composites and Their Applications: A Review. J Compos Sci 1–20. 10.3390/jcs2040066 Palanisamy S, Kalimuthu M, Nagarajan R, Fernandes Marlet JM, Santulli C, Physical (2023) Chemical, and Mechanical Characterization of Natural Bark Fibers (NBFs) Reinforced Polymer Composites: A Bibliographic Review. Fibers Selvaraj M, Pannirselvam N, Ravichandran PT, Bhuvaneshwaran M, Samson S (2023) Extraction and Characterization of a New Natural Cellulosic Fiber from Bark of Ficus Carica Plant as Potential Reinforcement for Polymer Composites. J Nat Fibers 20 Saravanakumar SS, Kumaravel A, Nagarajan T, Sudhakar P, Baskaran R (2013) Characterization of a novel natural cellulosic fiber from Prosopis juliflora bark. Carbohydr Polym 92:1928–1933 Adesina OT, Jamiru T, Sadiku ER, Ogunbiyi OF, Beneke L (2019) Mechanical evaluation of hybrid natural fibre – reinforced polymeric composites for automotive bumper beam: a review. Int J Adv Manuf Technol Thyavihalli Girijappa GY, Rangappa SM, Parameswaranpillai J, Siengchin S (2019) Natural Fibers as Sustainable and Renewable Resource for Development of Eco-Friendly Composites: A Comprehensive Review. Front Mater 6:1–14 Bichang DO, Aramide FO, Oladele IO, Alabi OO (2022) A Review on the Parameters Affecting the Mechanical, Physical, and Thermal Properties of Natural / Synthetic Fibre Hybrid. Advances in Materials Science and Engineering (2022) Bakhori Mohd SN et al (2022) Physical, Mechanical and Perforation Resistance of Natural-Synthetic Fiber Interply Laminate Hybrid Composites. Polymers (Basel) Kudva A, Gt M, K DP, Physical (2022) thermal, mechanical, sound absorption and vibration damping characteristics of natural fiber reinforced composites and hybrid fiber reinforced composites : A review and vibration damping characteristics of natural fiber reinforced composites and hybrid fiber reinforced composites : A review. Cogent Eng 9 Sahu V, Bisen KS, Krishna M (2015) Mechanical Properties of Sisal and Pineapple Fiber Hybrid Composites Reinforced With Epoxy Resin. Int J Mod Eng Res 5:32–38 Kumar A, Harendra S, Narang K, Bhattacharya S (2020) Mechanical properties of hybrid polymer composites: a review. J Brazilian Soc Mech Sci Eng. 10.1007/s40430-020-02517-w Gon D, Das K, Paul P, Maity S (2012) Jute Composites as Wood Substitute. Int J Text Sci 1:84–93 Salman SD, Leman Z, Sultan MTH, Ishak MR, Cardona F (2015) Hybrid Composites: A Review. Bio Resour 10:8580–8603 Sathishkumar TP, Naveen J, Satheeshkumar S (2014) Hybrid fiber reinforced polymer composites – A review. J Reinf Plast Compos 33 Jagannatha TD, Harish G (2015) Mechanical properties of carbon / glass fiber reinforced epoxy hybrid polymer composites. Int J Mech Eng Rob Res 4:131–137 Atiqah A, Chandrasekar M, Kumar TSM, Senthilkumar K, Ansari MNM (2019) Characterization and Interface of Natural and Synthetic Hybrid Composites Characterization and Interface of Natural and Synthetic Hybrid Composites. Encyclopedia of Renewable and Sustainable Materials. Elsevier Ltd.. doi: 10.1016/B978-0-12-803581-8.10805-7 . Jawaid M, Khalil HPS (2015) A. Cellulosic / synthetic fibre reinforced polymer hybrid composites: A review. Carbohydr Polym 86:1–18 Venkateshwaran N, Elayaperumal A, Sathiya GK, Composites (2012) Part B Prediction of tensile properties of hybrid-natural fiber composites. Compos Part B 43:793–796 Amico SC, Carvalho LH, Odila M, Cioffi H (2014) Hybrid Vegetable / Glass Fiber Composites. Lignocellulosic Polym Compos 63–82. 10.1002/9781118773949.ch4 Santhanam V, Dhanaraj R, Chandrasekaran M, Venkateshwaran N, Baskar S (2020) Experimental investigation on the mechanical properties of woven hybrid fiber reinforced epoxy composite. Mater Today Proc. 10.1016/j.matpr.2020.07.444 Selver E, Ucar N, Gulmez T (2017) Effect of stacking sequence on tensile, flexural and thermomechanical properties of hybrid flax / glass and jute / glass thermoset composites. J Ind Text 0:1–27 Sanjay MR et al (2018) Characterization and properties of natural fiber polymer composites: A comprehensive review. Journal of Cleaner Production vol. 172 Preprint at https://doi.org/10.1016/j.jclepro.2017.10.101 Rangappa SM, Siengchin S, Parameswaranpillai J, Jawaid M, Ozbakkaloglu T (2022) Lignocellulosic fiber reinforced composites: Progress, performance, properties, applications, and future perspectives. Polymer Composites vol. 43 Preprint at https://doi.org/10.1002/pc.26413 Rwawiire S, Tomkova B, Militky J, Kale BM, Prucha P (2015) Effect of Layering Pattern on the Mechanical Properties of Bark Cloth (Ficus natalensis) Epoxy Composites. Int J Polym Anal Charact 20:160–171 Rwawiire S et al (2016) Short-term creep of barkcloth reinforced laminar epoxy composites. Compos Part B 103:131–138 Velmurugan G et al (2024) Experimental investigation of mechanical and erosion properties of twill E-glass/sisal fiber reinforced hybrid polymer composite. Mater Today Proc. 10.1016/J.MATPR.2024.03.032 Ayyanar CB, Marimuthu K, Helaili S (2024) Experimental evaluation and numerical comparisons of pine tree leaves, graphene oxide loaded, and E-glass fiber reinforced sandwich composites. Int J Polym Anal Charact 29:363–384 Bharath KN et al (2019) Effect of stacking sequence on properties of coconut leaf sheath/jute/E-glass reinforced phenol formaldehyde hybrid composites. J Ind Text 49 Arpitha GR, Sanjay MR, Senthamaraikannan P, Barile C, Yogesha B (2017) Hybridization effect of sisal/glass/epoxy/filler based woven fabric reinforced composites. Exp Tech 41 Maich G et al (2015) Acacia bark residues as filler in polypropylene composites. Polímeros 25:289–295 Habib F (2024) Effect of Weight Fractions in Composite of Melinjo Stem Bark Fiber (Gnetum Gnemon). Am J Eng Res 13:147–153 Palanisamy S et al (2023) Tailoring Epoxy Composites with Acacia caesia Bark Fibers: Evaluating the Effects of Fiber Amount and Length on Material Characteristics. fibers Claude Martin YN, Koubaa A, Cloutier A, Soulounganga P, Wolcott M (2010) Effect of bark fiber content and size on the mechanical properties of bark / HDPE composites. Compos Part A 41:131–137 Sanjay M, Yogesha B (2017) Studies on hybridization effect of jute / kenaf / E-glass woven fabric epoxy composites for potential applications: Effect of laminate stacking sequences. J Ind Text 0:1–19 Pawar US, Chavan SS, Mohite DD (2024) Synthesis of glass FRP natural fiber hybrid composites (NFHC) and its mechanical characterization. Discover Sustain. 10.1007/s43621-024-00231-4 Asma B, Hamdi L, Ali B, Youcef M (2020) Flexural Mechanical Properties of Natural Fibre Reinforced Polymer Composites - A Statistical Investigation. Fibers and Polymers 21, 2321–2337 (2020) Karimzadeh A, Yahya MY, Abdullah MN, Wong KJ (2020) Effect of Stacking Sequence on Mechanical Properties and Moisture Absorption Characteristic of Hybrid PALF / Glass Fiber Composites. Fibers Polym 21:1583–1593 El-baky MAA, Megahed M, El-saqqa HH, Amal EA (2019) Mechanical Properties Evaluation of Sugarcane Bagasse-Glass / Polyester Composites. J Nat Fibers 00:1–18 Prabhu R et al (2017) Fabrication and Analysis of Jute, Glass and Flax Hybrid Composites Using Rice Husk Charcoal as Filler Material. Am J Mater Sci 7:135–139 Hanifawati IN, Azmah H, Sapuan MA, S. M., Zainudin ES (2011) Tensile and Flexural Behavior of Hybrid Banana Pseudostem/Glass Fibre Reinforced Polyester Composites. Key Eng Mater 471–472:686–691 Bindal A, Singh S, Batra NK, Khanna R (2013) Development of Glass/Jute Fibers Reinforced Polyester Composite. Indian Journal of Materials Science 1–6 (2013) Hashim MKR, Majid MSA, Jamir MRM, Kasim FH, Sultan MTH (2021) The effect of stacking sequence and ply orientation on the mechanical properties of pineapple leaf fibre (Palf)/carbon hybrid laminate composites. Polym (Basel) 13:1–24 Doğan MA, Gemi L, Yazman Ş, Ceritbinmez F, Yapici A (2024) Effect of hybridization and stacking sequence on damage development in AWJ machining of Al/FRP/Al FML composites. J Manuf Process 131:141–159 Mahmud SH et al (2024) Fabrication and mechanical performance investigation of jute/glass fiber hybridized polymer composites: Effect of stacking sequences. Next Mater 5:100236 Umar bin, Ashraf M et al (2024) Effect of fibre hybridization and stacking sequence on the low velocity impact response of flax/basalt/aluminum composite-metal joints. Compos Struct 331:117925 Dalbehera S, Acharya SK (2014) Study on mechanical properties of natural fiber reinforced woven jute-glass hybrid epoxy composites. Adv Polym Sci Technol 4:1–6 Altaee MA, Mostafa NH (2023) Mechanical properties of interply and intraply hybrid laminates based on jute glass / epoxy composites. J Eng Appl Sci 1–30. 10.1186/s44147-023-00293-7 Shahzad A, Nasir SU (2017) Mechanical Properties of Natural Fiber / Synthetic Fiber Reinforced Polymer Hybrid Composites Mechanical Properties . 10.1007/978-3-319-46610-1 Rachchh NV, Trivedi DN (2018) Mechanical Characterization and Vibration Analysis of Hybrid E-glass / Bagasse Fiber Polyester Composites. Mater Today Proc 5:7692–7700 Misri S, Leman Z, Sapuan SM, Ishak MR (2010) Mechanical properties and fabrication of small boat using woven glass / sugar palm fibres reinforced unsaturated polyester hybrid composite. IOP Conf Ser Mater Sci Eng 11:1–13 Hemalatha S, Ramesha N (2014) Tensile Properties of Natural Fiber-Reinforced Epoxy-Hybrid Composites. Indian J Adv Chem Sci 2:24–27 Kumar A, Singh S (2013) Analysis of mechanical properties and cost of glass/jute fiber-reinforced hybrid polyester composites. J Materials: Des Appl 0:1–7 Kumar SS (2020) Effect of Natural Fiber Loading on Mechanical Properties and Thermal Characteristics of Hybrid Polyester Composites for Industrial and Construction Fields. Fibers and Polymers 21, 1508–1514 (2020) Mohanta N, Acharya SK (2014) Investigation of mechanical properties of luffa cylindrica fibre reinforced epoxy hybrid composite. Int J Eng Sci Technol 7:1–10 Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5990257","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":413094540,"identity":"f56cf69a-d1fc-44ad-8901-2ac3cda0129a","order_by":0,"name":"Frances Alibet","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDElEQVRIiWNgGAWjYBAC9gYog4+ZB0hWSMiBOAce4NHCcwDKYANpOXDGwhisJYEoLQxALQfbKhLB1uLVIn342YMfFXXybOy8Bx9/YJNInx92+CHQFjs53QYcWvjSzA17zhw2bGPmSzY4wCORu/F2mgFQS7Kx2QHsWux5GMykGdsOMLYx85hJHJAAapmdANJyIHEbDi08POzfpBn/1dkDtZj/OGAgkW44O/0DAS08QFsamBNBtgBDSiJBXjqHkC08ZZI9xw4ng/wiceaAhOEG6ZyCAwkGuP0CdNg2iR81dbb9/GcPfqj8VycvPzt984cPFXZyuLRgAgOwSgNilYOAfAMpqkfBKBgFo2AkAADVrloQQ6j1sQAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-9345-7514","institution":"Moi University","correspondingAuthor":true,"prefix":"","firstName":"Frances","middleName":"","lastName":"Alibet","suffix":""},{"id":413094541,"identity":"067bdace-4098-4479-8fcd-f3a43aa9e7a0","order_by":1,"name":"Paul Wambua","email":"","orcid":"","institution":"The Technical University of Kenya","correspondingAuthor":false,"prefix":"","firstName":"Paul","middleName":"","lastName":"Wambua","suffix":""},{"id":413094542,"identity":"61f86559-f15e-4d00-b936-c0a956e74a7d","order_by":2,"name":"David Njuguna Githinji","email":"","orcid":"","institution":"Moi University","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"Njuguna","lastName":"Githinji","suffix":""},{"id":413094543,"identity":"b6d47621-405e-44ef-bc81-5f69119b4607","order_by":3,"name":"Samson Rwahwire","email":"","orcid":"","institution":"Busitema University","correspondingAuthor":false,"prefix":"","firstName":"Samson","middleName":"","lastName":"Rwahwire","suffix":""},{"id":413094544,"identity":"80657f76-80c1-49b4-91b7-9ee24c232443","order_by":4,"name":"Ocident Bongomin","email":"","orcid":"https://orcid.org/0000-0002-0430-2722","institution":"Moi University","correspondingAuthor":false,"prefix":"","firstName":"Ocident","middleName":"","lastName":"Bongomin","suffix":""}],"badges":[],"createdAt":"2025-02-09 02:58:46","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-5990257/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5990257/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":76366136,"identity":"721d62dd-f330-44cd-ad41-f7ee1e9364bc","added_by":"auto","created_at":"2025-02-15 15:54:54","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1339276,"visible":true,"origin":"","legend":"\u003cp\u003ecomposite reinforcement materials (a) Bark cloth; (b) Glass fibre mat/fabric\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/f82da00c87096e388dd6b4af.png"},{"id":76366344,"identity":"b476c9b4-9753-4f31-ae8a-aefc170c96ed","added_by":"auto","created_at":"2025-02-15 16:02:54","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2191415,"visible":true,"origin":"","legend":"\u003cp\u003eComposite fabrication (a) Cleaning mould; (b) Mould set up; (c) Mixing resin and catalyst; (d) Laying reinforcements and resin impregnation; (e) Bubble removal and squeezing out excess resin using a roller prior to drying; (f) Fabricated composites.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/8b34f5c3a1821d5f00a5beaf.png"},{"id":76366138,"identity":"10cabf55-4b0a-4989-af51-234bd9da1816","added_by":"auto","created_at":"2025-02-15 15:54:54","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2489347,"visible":true,"origin":"","legend":"\u003cp\u003eFailed composites after mechanical tests (a) After flexural test; (b) after tension test; (c) after compression test; (d) after impact test\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/6c10892f30a142cb5ba587bc.png"},{"id":76366147,"identity":"03604f25-634a-4304-91ff-74b2c3295221","added_by":"auto","created_at":"2025-02-15 15:54:54","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":47159,"visible":true,"origin":"","legend":"\u003cp\u003eFlexural, tensile, and compressive strengths as a function of hybrid ratio at 15% and 25% fibre weight fraction\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/2ed261fcd9f9ae74e4fce205.png"},{"id":76366140,"identity":"309d19af-4522-4c3e-969b-7d3e76e90796","added_by":"auto","created_at":"2025-02-15 15:54:54","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":39362,"visible":true,"origin":"","legend":"\u003cp\u003eImpact strength as a function of hybrid ratio at 15% and 25% fibre weight fraction\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/289e1c600de30cbb32f33d19.png"},{"id":76366142,"identity":"e372cb4a-42cf-414c-abc9-61d6eacc9378","added_by":"auto","created_at":"2025-02-15 15:54:54","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":66724,"visible":true,"origin":"","legend":"\u003cp\u003eFlexural, tensile, and compressive strengths as a function of varying reinforcement stacking sequence\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/565abe6dfde1e6ea5b6319b8.png"},{"id":76366346,"identity":"7cdb4416-eb6f-4e0d-be5e-8df75d9b3261","added_by":"auto","created_at":"2025-02-15 16:02:54","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":51769,"visible":true,"origin":"","legend":"\u003cp\u003eImpact strength of composites as a function of varying stacking reinforcement stacking sequence\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/a9e3e75978cfb71001eb87a3.png"},{"id":76366348,"identity":"313769c1-d7c4-4dc1-88a3-10a97670e43b","added_by":"auto","created_at":"2025-02-15 16:02:54","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":3073526,"visible":true,"origin":"","legend":"\u003cp\u003eSurface morphology and cross-section SEM analysis of hybrid composite; (a, b) B-G-G-B hybrid; (c, d) B-G-B-G hybrid; (e, f) G-G-B-G hybrid.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/fba47f4295a3c9022ea6483d.png"},{"id":76367280,"identity":"5dfd2410-42fa-44fb-9bff-60fdffe683b1","added_by":"auto","created_at":"2025-02-15 16:19:01","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":14815798,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5990257/v1/c54b5e99-967b-4f5d-a031-5e19e870e997.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eFabrication and mechanical performance of bark cloth/glass fiber reinforced hybrid polymer composites for automotive applications\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eBark cloth is a unique, non-woven fibrous textile produced from the bark of various tree species, with \u003cem\u003eFicus natalensis\u003c/em\u003e being the primary species used in Uganda. Locally known as \"mutuba,\" this tree grows naturally in Uganda's tropical climate and requires minimal care, as it thrives without the need for fertilizers. \u003cem\u003eFicus natalensis\u003c/em\u003e, along with other species such as \u003cem\u003eAntiaris toxicaria\u003c/em\u003e and \u003cem\u003eFicus brachypoda\u003c/em\u003e, is particularly valued for its renewable nature. The bark of the tree can be harvested annually without felling the tree, making it a sustainable resource\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. A single tree can continue to produce bark cloth for over 30 years, with the bark regenerating after each harvest\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe production of bark cloth involves stripping the bark from the tree, which is then processed through steaming and beating with carved wooden hammers. This traditional method, passed down through generations, stretches the fibers and creates the distinctive terracotta-colored cloth. The cloth holds cultural significance in Uganda, being used for royal garments, religious ceremonies, and funerals\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. The importance of bark cloth to Ugandan culture led UNESCO to recognize it as a \"Masterpiece of the Intangible Cultural Heritage of Humanity,\" emphasizing the need to protect the knowledge and traditions surrounding its production\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn addition to its cultural value, bark cloth has gained attention for its potential as a reinforcement material in composite applications. Studies have shown that bark cloth consists of cellulosic microfibers aligned at 45\u0026deg; angles, providing moderate tensile properties. Scanning Electron Microscopy (SEM) analysis revealed that the fibers are oval-shaped and bonded by lignin and hemicelluloses, with diameters ranging between 10 and 20 \u0026micro;m\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. The strength of bark cloth was measured at 101.7 N longitudinally and 23.5 N transversely, with a fabric thickness of approximately 1.084 mm\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. These properties, along with its thermal stability below 200\u0026deg;C, suggest that bark cloth can be used for composite reinforcement, particularly in applications where lightweight and biodegradable materials are desirable\u003csup\u003e\u003cspan additionalcitationids=\"CR7 CR8 CR9\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eDespite its potential due to its sustainability, low density, and cost-effectiveness, the key challenges in using bark cloth and other natural fibers for structural applications, particularly in the automotive industry, is their durability. Natural fibers have a high affinity for moisture due to their hydrophilic nature, which can lead to water absorption and subsequently reduced mechanical performance over time. For example, prolonged exposure to moisture can cause swelling, fiber debonding, and degradation of fiber-matrix adhesion, leading to a significant reduction in properties such as tensile and flexural strength. In addition, they generally exhibit lower mechanical properties than synthetic fibers, such as glass and carbon fiber, which limits their use in high-performance applications\u003csup\u003e\u003cspan additionalcitationids=\"CR12 CR13\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. To address these limitations, researchers have explored hybrid composites that combine natural fibers with synthetic fibers. Hybrid composites leverage the sustainability of natural fibers while benefiting from the mechanical strength of synthetic fibers. This combination offers improved mechanical performance, including tensile, flexural, and impact strengths\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eRecent studies have shown that treatments or hybridization with synthetic fibers, such as glass, can mitigate these effects by reducing moisture absorption and improving long-term stability\u003csup\u003e\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan additionalcitationids=\"CR20 CR21 CR22 CR23 CR24\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. For example, Santhanam et al.\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e reported significant improvements in tensile and flexural strength when glass fibers were added to banana fiber/polyester composites. Similarly, Selver et al.\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e demonstrated that hybrid composites made from jute and glass fibers showed enhanced mechanical properties compared to pure natural fiber composites. Sanjay et al.\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e reviewed the mechanical properties of natural fiber polymer composites, emphasizing that water absorption is a major factor affecting their long-term durability. The review suggests that hybridizing natural fibers with synthetic fibers or applying surface treatments can significantly mitigate these durability issues, improving the composites' resistance to environmental degradation. Another important aspect of improving natural fiber composites is enhancing their mechanical and moisture-resistant properties by hybridization. Sanjay et al.\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e discussed how hybridizing lignocellulosic fibers with synthetic fibers, such as glass, leads to composites that demonstrate improved mechanical properties and better resistance to moisture and environmental stresses. The incorporation of synthetic fibers into natural fiber composites not only improves their structural performance but also increases their applicability in sectors such as automotive and construction, where environmental resistance is critical\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. Our study builds upon these findings by investigating the mechanical performance of hybrid composites made from bark cloth and E-glass fibers, with an emphasis on their potential for automotive applications.\u003c/p\u003e \u003cp\u003eThe hybridization of natural fibers with E-glass fibers offers several significant advantages in composite materials, particularly for applications requiring high performance and sustainability\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. Natural fibers, such as coconut leaf sheath, jute, and sisal, are lightweight and biodegradable, contributing to both weight reduction and environmental sustainability. However, their mechanical properties are often lower compared to synthetic fibers like E-glass. Studies by Bharath et al.\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e and Arpitha et al.\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e show that the combination of these natural fibers with E-glass fibers significantly enhances tensile and flexural strength, making the resulting hybrid composites suitable for structural and automotive applications. The hybridization also provides cost benefits, as natural fibers are more affordable than synthetic materials. Moreover, the addition of E-glass fibers improves the durability and resistance to moisture of the composites, addressing the common limitation of natural fibers in harsh environmental conditions. This balance of enhanced mechanical performance, cost-effectiveness, and sustainability makes hybrid composites highly attractive for a variety of industrial uses.\u003c/p\u003e \u003cp\u003eThe automotive industry, in particular, has shown great interest in hybrid composites due to their potential to reduce vehicle weight while maintaining strength and durability. The use of natural fibers in automotive components can reduce both material costs and environmental impact\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. For example\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e, highlighted the role of natural fiber composites in the production of non-structural parts, while a number of studies have emphasized their potential to replace traditional materials such as aluminum and glass fibers in specific applications\u003csup\u003e\u003cspan additionalcitationids=\"CR38\" citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. Hybrid composites, with their tailored mechanical properties, offer the versatility needed for a wide range of applications in automotive, construction, and other industries\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe mechanical properties of hybrid composites depend on several factors, including fiber weight fraction, hybrid ratio (the proportion of natural to synthetic fibers), and stacking sequence (the arrangement of fibers within the composite)\u003csup\u003e\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e,\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. Studies have shown that increasing the glass fiber content improves the mechanical properties of hybrid composites\u003csup\u003e\u003cspan additionalcitationids=\"CR44\" citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e. These studies reported that the tensile and flexural strength of hybrid composites increased with higher glass fiber content, while excessive natural fiber content led to poor fiber-matrix adhesion\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e,\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e Additionally, the stacking sequence of fibers plays a critical role in determining the composite's mechanical properties\u003csup\u003e\u003cspan additionalcitationids=\"CR49 CR50\" citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u003c/sup\u003e. For example, Sanjay et al.\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e found that placing glass fibers in the outer layers of hybrid composites significantly improved flexural strength compared to composites with natural fibers on the surface.\u003c/p\u003e \u003cp\u003eResearch has demonstrated the effectiveness of hybridization in improving the mechanical properties of composites. For instance, Santhanam et al.\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e found that hybrid composites with glass and natural fibers exhibit superior flexural and tensile properties. Other studies have confirmed the benefits of hybridization, including Dalbehera et al.\u003csup\u003e\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e who observed improved impact strength and stiffness in jute/glass hybrid composites. Moreover, Altaee et al.\u003csup\u003e\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e reported that hybrid composites with glass fibers in the outer layers and natural fibers in the core can offer optimal mechanical performance for specific applications, such as load-bearing and structural components.\u003c/p\u003e \u003cp\u003eDespite extensive research on hybrid composites using fibers such as jute, flax, and sisal, studies on bark cloth hybrid composites are still limited. However, recent research has shown that bark fibers from other plants, such as \u003cem\u003eFicus carica\u003c/em\u003e and \u003cem\u003eProsopis juliflora\u003c/em\u003e, possess desirable properties for composite reinforcement, including high cellulose content and thermal stability\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. These findings suggest that bark cloth has the potential to be an effective reinforcement material when hybridized with synthetic fibers.\u003c/p\u003e \u003cp\u003eThis study aims to fill the research gap by investigating the mechanical properties of bark cloth (\u003cem\u003eFicus natalensis\u003c/em\u003e) and glass fiber hybrid composites. Specifically, it focuses on the effects of fiber weight fraction, hybrid ratio, and stacking sequence on flexural, tensile, compressive, and impact strengths. The study seeks to optimize these parameters to enhance the performance of bark cloth-based hybrid composites, making them suitable for use in automotive, construction, and other industrial applications where sustainability and strength are key requirements.\u003c/p\u003e"},{"header":"Materials and Method","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaterials\u003c/h2\u003e \u003cp\u003eThe materials used in this study include bark cloth, harvested from \u003cem\u003eFicus natalensis\u003c/em\u003e trees in Mukoko village, Masaka district, Uganda, and commercially available glass fabric (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Unsaturated polyester resin, with a density of 1.12 g/cm\u0026sup3;, was used as the matrix, combined with methyl ethyl ketone peroxide (MEKP) catalyst in a ratio of 100:1 by weight. The glass fiber mat and resin were procured from Narkhi Enterprises Limited in Nairobi, Kenya. The characteristics of glass fiber and the unsaturated polyester resin is presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCharacteristics of glass fibers and unsaturated polyester resin\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProperties\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGlass fibers\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePolyester resin\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAppearance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eOpaque\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eViscosity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4\u0026ndash;5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWater absorption (%) (7 day value)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeat distortion temperature (◦C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e63.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eElongation at break (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.1\u0026ndash;4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBending Strength (kgf/mm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBending Modulus (kgf/mm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e523.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTensile Strength (kgf/mm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e203.94\u0026ndash;356.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eImpact Strength (kgf-cm/cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDensity (g/cm3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.5\u0026ndash;2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eToughness (MJ/m\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40\u0026ndash;50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTensile modulus (GPa)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70\u0026ndash;76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFiber diameter (\u0026micro;m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11\u0026ndash;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMoisture Content (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eBark Cloth and Glass fabric Characterization\u003c/h3\u003e\n\u003cp\u003eThe characterization of bark cloth and glass fiber mat (also known as non-woven glass fabric) was conducted to determine their thickness, areal density, and tensile strength (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The thickness was measured using a digital thickness gauge under a pressure of 1 kPa, with the average thickness of five specimens recorded. Areal density was determined by cutting samples into 0.1 x 0.1 m squares and weighing them with an electronic balance, following ASTM D6242-98. Tensile strength was tested in both the longitudinal and transverse directions according to ASTM D5035-95 (Strip Method), using a Universal Testing Machine. The glass fiber mat\u0026rsquo;s areal density and fiber length were also characterized, with fiber length measured based on ISO 6989:1981 standards.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eProperties of bark cloth and non-woven glass fabric\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProperties\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBark\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGlass\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFabric type\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNon-woven\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNon-woven\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComposition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100% bark\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100% E-glass\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFabric thickness (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAreal density (gsm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e385.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e394.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLongitudinal tensile strength (MPa)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTransverse tensile strength (MPa)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFibre length (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eComposite Fabrication\u003c/h3\u003e\n\u003cp\u003eThe composites were fabricated using the hand layup technique in a steel mold measuring 300 mm x 300 mm x 20 mm, with a polished lid. Bark cloth and glass fiber mats were cut according to the mold dimensions as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The polyester resin, catalyzed with methyl ethyl ketone peroxide (MEKP), was used as the matrix material. The fabrication process involved laying the first reinforcement layer into the mold, followed by resin application and consolidation with a roller to eliminate air voids. Subsequent layers were applied to achieve the desired hybrid structure, varying the stacking sequence and fiber weight fractions. Four layers of reinforcement were used.\u003c/p\u003e \u003cp\u003eA consolidation pressure of 3.57 kN/m\u0026sup2; was applied, and the composites were cured at room temperature for 7 hours before demolding. In this study, various composite samples were prepared by varying two key factors: fiber weight fraction and the hybrid ratio of bark cloth to glass fiber. The experiments were designed to assess how these variations affect the mechanical properties of the hybrid composites. The fiber weight fraction was set at 15%, 20%, and 25%, while the hybrid ratio of bark cloth to glass fiber ranged from 3:1, 2:2, 1:3. Two control composites with bark cloth to glass fiber ratio of 4:0 and 0:4 respectively, were also fabricated. Ten types of composite samples were produced, as outlined in \u003cb\u003eTable\u0026nbsp;3\u003c/b\u003e. These samples were fabricated by adjusting both the fiber weight fraction and the reinforcement stacking sequence. The samples included controls with either 100% bark cloth or 100% glass fiber. The hybrid composites consisted of varying combinations of bark cloth and glass fiber, arranged in different stacking sequences. By varying the fiber weight fraction and hybrid ratio, a comprehensive analysis of how these factors influence the mechanical behavior of bark cloth/glass fiber hybrid composites was achieved.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eExperimental design for producing the different composite sample types\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComposite sample types\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFibre weight fraction \u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWeight of fibres\u003c/p\u003e \u003cp\u003e (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eResin weight\u003c/p\u003e \u003cp\u003e (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCatalyst weight\u003c/p\u003e \u003cp\u003e (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eComposite\u003c/p\u003e \u003cp\u003edesignation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eReinforcement\u003c/p\u003e \u003cp\u003estacking sequence\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e92.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e520.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3B1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eB-B-G-B\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e107.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e320.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3B2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eB-B-G-B\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e134.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e755.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3G1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eG-G-B-G\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e138.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e409.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3G2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eG-G-B-G\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e88.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e349.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eB-B-B-B\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e159.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e630.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eG\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eG-G-G-G\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e104.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e411.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eBG1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eB-G-B-G\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e109.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e431.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eBG2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eB-G-G-B\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e113.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e447.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eBG3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eG-B-B-G\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e132.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e524.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eBG4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eB-B-G-G\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eMechanical Testing\u003c/h3\u003e\n\u003cp\u003eComposite samples were prepared and cut in accordance with ASTM and ISO standards to ensure uniformity across all tests. Prior to testing, the specimens were conditioned in the laboratory for 48 hours at a temperature of 23\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C and relative humidity of 65%, which ensured that the mechanical properties were assessed under controlled conditions. This helped to minimize the effects of moisture and temperature variations on the results.\u003c/p\u003e \u003cp\u003eThe flexural strength of the composites was determined following ASTM D790. The test was conducted using a computer-controlled Testomeric machine (Model M/C S/No: 500-10171) with a 24.5 kN capacity, operating at a crosshead speed of 10 mm/min. The span length was calculated as 16 times the specimen thickness, and the specimen width was one-quarter of the span length, with an additional 25 mm overhanging allowance on both ends. The test involved applying a load at the center of the specimen until failure occurred, with five specimens tested for each composite type. Flexural strength is a crucial property for determining a material's resistance to bending, particularly in applications such as automotive and structural components.\u003c/p\u003e \u003cp\u003eTensile strength tests were conducted in accordance with ASTM D3039, using a Universal Testing Machine (Model UT-10; S/No: 2015/12) with a 100 kN capacity at a crosshead speed of 5 mm/min. The specimens had dimensions of 300 mm in length, 25 mm in width, and a gauge length of 200 mm. Tensile strength is important for assessing the material\u0026rsquo;s resistance to tension and stretching forces, which is relevant for applications where the composites will undergo pulling or stretching stresses.\u003c/p\u003e \u003cp\u003eCompressive strength tests were performed following ASTM D3410M, also using the Universal Testing Machine (Model UT-10; S/No: 2015/12) with a 100 kN capacity at a crosshead speed of 5 mm/min. Specimens were prepared with a length of 40 mm, a width of 25 mm, and a gauge length of 40 mm. This test measures the composite\u0026rsquo;s ability to withstand compressive forces and eliminates the possibility of buckling, which is critical for evaluating the performance of the composites in load-bearing applications.\u003c/p\u003e \u003cp\u003eImpact strength was measured using an impact tester (Model HLE; S/No: 2015/15) according to ISO 179-1:2000 standards. The impact test was conducted with a 15 J hammer, and the specimens had a length of 60 mm, a width of 10 mm, and a span length of 40 mm. All the specimens were un-notched to evaluate their natural resistance to impact. Impact strength is an essential measure of a material\u0026rsquo;s ability to absorb energy and resist sudden forces, which is especially important for safety-critical applications such as in the automotive industry.\u003c/p\u003e \u003cp\u003eFor all mechanical tests, five specimens were tested for each composite type, and the average values were reported. These mechanical tests are vital for understanding the overall performance of the hybrid composites and determining their potential for use in various engineering applications.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eThe experimental data obtained from the mechanical tests were statistically analyzed to determine the significance of the effects of fiber weight fraction and hybrid ratio on the mechanical properties of the composites. One-way Analysis of Variance (ANOVA) was used to assess the significance of differences in the flexural, tensile, compressive, and impact strengths of the various composite samples. The ANOVA was performed at a 95% confidence level, with a p-value of less than 0.05 considered statistically significant. The F-values and p-values were reported for each mechanical property to quantify the influence of the composite parameters. This statistical analysis provided a robust evaluation of the experimental results, identifying which factors had a significant effect on the performance of the bark cloth/glass fiber hybrid composites.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eSEM Analysis\u003c/h2\u003e \u003cp\u003eThe Scanning Electron Microscopy (SEM) analysis was performed to investigate the surface morphology and cross-sectional structure of hybrid composites with various stacking sequences of bark cloth (B) and glass fibers (G). The samples were prepared with sequences G-G-B-G, B-G-B-G, and B-G-G-B. Small sections were cut from each composite for analysis. SEM images were taken using a VEGA3 TESCAN SEM at an accelerating voltage of 5.0 kV, with magnifications set at 250x for surface analysis and 2.00kx for cross-sectional analysis. The images provided insights into fiber pull-out, microvoids, and the fiber-matrix interaction, highlighting areas of poor resin impregnation and bonding. This methodology enabled a detailed assessment of the structural integrity and mechanical behavior of the composites.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eThe mechanical properties of the bark cloth and glass fabric hybrid composites were analyzed based on flexural, tensile, compressive, and impact strength tests. The effects of varying fiber weight fractions and hybrid ratios (bark cloth to glass fabric) on these properties were investigated to evaluate the performance of the composites. Composite thickness ranged from 4.0 mm to 5 mm. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e depicts the failed composites after undergoing the necessary named tests. As seen, most composites failed within acceptable levels.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eFlexural Strength\u003c/h3\u003e\n\u003cp\u003eThe flexural strength of the bark cloth and glass fiber hybrid composites was significantly influenced by the hybrid ratio and fiber weight fractions of 15%, 20%, and 25%, as shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Composites with a higher proportion of glass fiber consistently exhibited superior flexural performance compared to those with a higher proportion of bark cloth. These results align with previous research, which also observed that synthetic fibers like glass provide enhanced mechanical reinforcement in hybrid composites. For instance, Hanifawati et al.\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e reported a notable improvement in tensile and flexural strength when glass fiber was added to a banana fiber/polyester matrix. Similarly, Bindal et al.\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e demonstrated that hybrid composites made from natural and synthetic fibers, such as jute/glass, exhibited improved flexural properties compared to pure natural fiber composites.\u003c/p\u003e \u003cp\u003eAt 20% fiber weight fraction, composites showed better overall flexural performance than the 25% fiber weight fraction composites, but they were still slightly inferior to the 15% weight fraction composites, suggesting that 20% provides a balanced performance when fiber content and resin wetting are optimized. The observed poor performance at 25% fiber weight fraction is likely due to insufficient resin for fiber wetting, leading to poor fiber-matrix adhesion. Studies like Shahzad et al.\u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e corroborate this observation, reporting that fiber agglomeration at higher content can lead to a decrease in mechanical properties due to inefficient load transfer between fibers. Additionally, Rachchh et al.\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e found that increasing the natural fiber content beyond optimal levels in glass/natural fiber composites leads to decreased tensile and flexural strength, further supporting our results. The ANOVA results (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) for flexural strength indicated significant differences across hybrid ratios at all fiber weight fractions (15%, 20%, and 25%), with p-values lower than 0.05. The 20% fiber weight fraction composites showed improved performance compared to the 25% composites, likely due to better fiber distribution and resin penetration.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAnalysis of variance for effect of hybrid ratio on bark cloth and glass fabric reinforced polyester composites\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMechanical Property\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFiber weight fraction\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSource of Variation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e 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char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"8\" rowspan=\"9\"\u003e \u003cp\u003eTensile\u003c/p\u003e \u003cp\u003estrength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e870.1158\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e 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char=\".\" colname=\"c4\"\u003e \u003cp\u003e1065.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3329.748\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e665.9497\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e60.79107\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e7.7E-13\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e262.9135\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e10.95473\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3592.662\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e25%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e841.6228\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e841.6228\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e131.7509\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e3.01E-06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e51.10388\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.387985\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e892.7266\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"8\" rowspan=\"9\"\u003e \u003cp\u003eCompressive\u003c/p\u003e \u003cp\u003e strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e60.12304\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e60.12304\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.496407\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.501076\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e968.9316\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e121.1165\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1029.055\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3847.087\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e769.4174\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.87158\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.5E-05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1698.559\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e70.77329\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5545.646\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e25%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e290.8445\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e290.8445\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e45.23302\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.000149\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e51.43932\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.429915\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e342.2838\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"8\" rowspan=\"9\"\u003e \u003cp\u003eImpact\u003c/p\u003e \u003cp\u003estrength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e15%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.21284\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.21284\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.387706\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.55084\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e107.5627\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e13.44534\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e112.7756\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e398.1756\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e79.63512\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8.52665\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e9.43E-05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e224.1493\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9.339555\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e622.3249\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e25%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBetween Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e23.13441\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e23.13441\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.398344\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.270952\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e132.3532\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e16.54415\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e155.4876\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eTensile Strength\u003c/h2\u003e \u003cp\u003eTensile strength results mirrored the flexural strength trend, with higher glass fiber content improving the tensile strength of the hybrid composites (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). This is consistent with findings from Misri et al.\u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e, who reported that the inclusion of glass fiber in sugar palm composites increased tensile strength by 59.20%. The highest tensile strength was observed at 15% fiber weight fraction, while the 20% fiber weight fraction composites performed better than those with 25%. The superior tensile performance at 15% can be attributed to better resin penetration and more uniform fiber distribution. Composites with a 1:3 hybrid ratio and glass fibers in higher proportion, such as composite BG3, exhibited the best tensile performance at 20% fiber weight fraction due to improved load transfer from the glass fibers.\u003c/p\u003e \u003cp\u003eSimilar observations were made by Hemalatha et al.\u003csup\u003e\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e\u003c/sup\u003e, who found that hybrid composites with higher synthetic fiber content, such as jute/glass composites, showed enhanced tensile performance due to better load transfer and fiber-matrix adhesion. In contrast, the 25% fiber weight fraction composites, such as 3B2 (B-B-G-B), exhibited reduced tensile strength, which could be attributed to insufficient resin and poor wetting of the fibers. According to Kumar et al.\u003csup\u003e\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e\u003c/sup\u003e, higher natural fiber content increases matrix absorption, reducing resin availability for fiber wetting, which is a critical factor in tensile performance. The ANOVA results (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) for tensile strength at all fiber weight fractions (15%, 20%, and 25%) showed statistically significant differences (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), confirming that the hybrid ratio and fiber content played a crucial role in determining the tensile behavior of the composites.\u003c/p\u003e \u003cp\u003e \u003cb\u003eCompressive Strength\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe compressive strength tests revealed that hybrid composites with higher glass fiber content exhibited superior performance (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e), which aligns with the findings of Misri et al.\u003csup\u003e\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e, who reported that glass fibers provide superior resistance to compressive forces in hybrid composites. The 1:3 hybrid ratio composites showed the highest compressive strength at both 15% and 20% fiber weight fractions, with the latter providing a balanced performance. Composites with a 20% fiber weight fraction outperformed those with 25%, likely due to fewer agglomeration issues and better resin penetration. At 25% fiber weight fraction, composites suffered from reduced compressive strength due to inadequate resin distribution and fiber agglomeration, which hindered uniform load distribution.\u003c/p\u003e \u003cp\u003eThe reduction in compressive strength at 25% fiber weight fraction can be attributed to fiber agglomeration and poor fiber-matrix adhesion, as observed in previous studies\u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. In glass/natural fiber hybrid composites, Rachchh et al. \u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e reported that exceeding an optimal natural fiber content led to reduced compressive strength due to uneven fiber distribution and resin starvation.\u003c/p\u003e \u003cp\u003eThe ANOVA results (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) for compressive strength indicated significant differences at both 20% and 25% fiber weight fractions, with p-values below 0.05, confirming the importance of hybrid ratio and fiber content in determining compressive performance.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eImpact Strength\u003c/h2\u003e \u003cp\u003eThe impact strength of the hybrid composites increased with the inclusion of glass fibers, consistent with findings from Kumar\u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e, who noted that good fiber-matrix adhesion improves impact resistance. At 20% fiber weight fraction, composite BG4 (B-B-G-G) exhibited the highest impact strength of 27.50 kJ/m\u0026sup2;, surpassing the performance of 25% composites. The presence of glass fibers in the outer layers facilitated effective load transfer during impact, allowing the composite to absorb and dissipate energy more efficiently.\u003c/p\u003e \u003cp\u003eSimilar trends were reported by Mohanta et al.\u003csup\u003e\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e, where hybrid composites with synthetic fibers in the outer layers showed superior impact resistance compared to natural fiber composites. The impact performance of the 25% fiber weight fraction composites was lower due to fiber agglomeration and insufficient resin penetration, as noted by Shahzad et al.\u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e, and Rachchh et al.\u003csup\u003e\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAt 20% fiber weight fraction, hybrid composite BG4 (B-B-G-G) exhibited the highest impact strength of 27.50 kJ/m\u0026sup2; (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), outperforming the 25% composites but slightly underperforming compared to the 15% composites. The presence of glass fibers in the outer layers facilitated effective load transfer during impact, resulting in better energy absorption and distribution. This improvement in impact resistance is similar to the findings of Kumar\u003csup\u003e\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e, where good fiber-matrix adhesion improved impact strength.\u003c/p\u003e \u003cp\u003eThe ANOVA results (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) for impact strength at 20% fiber weight fraction revealed significant differences (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), confirming that hybridization and fiber arrangement contributed to the improved impact resistance of the composites. The 20% composites performed better than the 25% composites due to better fiber-matrix bonding and fewer fiber agglomeration issues.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eEffect of stacking sequence\u003c/h2\u003e \u003cp\u003eThe stacking sequence had a profound impact on the mechanical performance of the hybrid composites, particularly at 20% fiber weight fraction. As seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, composites with glass fibers in the outer layers exhibited higher mechanical properties across flexural, tensile, and compressive strengths. The importance of the stacking sequence in enhancing the mechanical properties of natural fiber-based composites has been reported in previous studies\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e. In this study, composite BG3 (G-B-B-G) at 20% fiber weight fraction showed the best tensile strength, which can be attributed to the advantageous placement of glass fibers in the outer layers, improving load distribution. Similarly, composite BG4 (B-B-G-G) exhibited the highest impact strength (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e), benefiting from the glass fibers on the outer side, which facilitated effective load transfer during impact.\u003c/p\u003e \u003cp\u003eAt 20% fiber weight fraction, the stacking sequence played a crucial role in optimizing the balance between the rigidity provided by glass fibers and the flexibility and sustainability of bark cloth. The 20% composites outperformed the 25% composites due to better fiber distribution and fewer agglomeration issues. When glass fibers were placed as the outer layers, as in BG3 and BG4, the composites showed significant improvements in mechanical performance compared to configurations where bark cloth was in the outer layers, such as B-G-G-B.\u003c/p\u003e \u003cp\u003eThe results also showed that hybrid composites with alternating layers of bark cloth and glass fiber outperformed pure bark cloth composites in all mechanical properties. For instance, the flexural strength of hybrid composites increased by 137.98%, tensile strength by 81.59%, and compressive strength by 51.58% compared to pure bark cloth composites. These findings align with studies such as Santhanam et al.\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, which found that stacking sequence had a more substantial effect on flexural and impact strength than tensile strength.\u003c/p\u003e \u003cp\u003eThe ANOVA results (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) for the effect of stacking sequence on flexural, tensile, compressive, and impact strengths at 20% fiber weight fraction confirmed significant differences (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The F-ratio values were higher than the F-criteria values, indicating that the stacking sequence significantly affected the performance of the composites. The highest mechanical properties were consistently observed in composites with glass fibers in the outer layers, such as BG3 and BG4.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eSurface Morphology and Cross-Section Analysis\u003c/h2\u003e \u003cp\u003eThe SEM analysis of the B-G-G-B hybrid composite highlights both surface and cross-sectional features that provide insights into the material's structure and performance. In the surface morphology at 250x magnification (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea), roughness and fiber pull-out are visible, indicating regions of incomplete resin impregnation. These voids and surface irregularities suggest that the bonding between the matrix and fibers, especially in the bark cloth layers, may not be sufficient, which could lead to stress concentration points and reduced mechanical integrity.\u003c/p\u003e \u003cp\u003eIn the cross-sectional view at 2.00kx magnification (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb), the glass fiber layers are well integrated, showing a more uniform bond with the matrix. However, the bark cloth layers exhibit fiber pull-out and weaker bonding, with voids observed between the fibers and the matrix. This indicates potential flaws in the resin impregnation process, particularly in the natural fiber regions. These imperfections could act as points of failure under mechanical stress, compromising the overall durability of the composite\u003csup\u003e\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eFor the B-G-B-G hybrid composite, the SEM analysis also reveals rough surface morphology (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ec), with significant fiber pull-out and voids, again suggesting incomplete resin impregnation. The bark cloth fibers show weaker bonding compared to the glass fibers. In the cross-section (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ed), glass fibers appear more consistently bonded to the matrix, while the bark cloth layers are less integrated, with visible fiber pull-out and voids that could reduce mechanical strength.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFinally, for the G-G-B-G hybrid composite, surface analysis shows a similar roughness, with some regions exhibiting fiber pull-out (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ee). In the cross-section (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ef), the glass fibers are well embedded, but the bark cloth layers show weaker bonding and void formation, indicating potential weaknesses in fiber-matrix adhesion. These defects highlight the need for improved resin infiltration and fiber alignment to enhance the composite's overall structural integrity and mechanical performance.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrated that hybridizing bark cloth with glass fibers significantly enhances the mechanical properties of polyester composites, particularly in terms of flexural, tensile, compressive, and impact strengths. Composites with higher glass fiber content exhibited superior performance, especially when glass fibers were positioned on the outer layers. The 15% and 20% fiber weight fractions produced better mechanical properties due to improved resin wetting and reduced fiber agglomeration, while the 25% fiber weight fraction composites showed weaker performance due to insufficient resin and fiber clumping. The stacking sequence also played a critical role, with alternating layers of bark cloth and glass fibers showing enhanced load distribution and energy absorption. The 1:3 hybrid ratio (glass to bark cloth) and 20% fiber weight fraction provided an optimal balance between material efficiency and mechanical performance. Statistical analysis confirmed that the hybrid ratio, fiber weight fraction, and stacking sequence significantly influenced the composites' mechanical properties. The SEM analysis revealed that incomplete resin impregnation and the presence of microvoids, particularly in the bark cloth layers, contributed to fiber pull-out and weaker fiber-matrix bonding, highlighting the need for optimized resin infiltration and fiber alignment to improve the composite\u0026rsquo;s mechanical performance and durability\u003c/p\u003e \u003cp\u003eFurther, it is recommended to explore different natural fibers and hybrid ratios to further optimize performance, investigate resin formulations or surface treatments to improve fiber-matrix adhesion, especially at higher fiber content, and evaluate the composites' long-term durability and environmental resistance in real-world applications. These improvements could expand the use of hybrid composites in various structural and load-bearing applications, promoting sustainability without compromising performance.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflicts of Interest\u003c/h2\u003e \u003cp\u003eThe authors declare that there are no conflicts of interest regarding publication of this paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThe authors are grateful to the Management of Moi University-Kenya, Multimedia University-Kenya, and Busitema University-Uganda where the tests were carried out from. Frances Alibet is grateful to the World Bank for the scholarship awarded to her through the Africa Centre of Excellence II in Phytochemicals, Textiles and Renewable Energy (ACE II PTRE-Credit no. 5798-KE ) at Moi University-Kenya.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e \u003cp\u003eData available within the manuscript.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution Statement \u003c/h2\u003e\n\u003cp\u003e\u003cstrong\u003eFrances Alibet:\u0026nbsp;\u003c/strong\u003econceptualization, methodology, investigation, formal analysis, data curation, writing\u0026mdash;original draft, and writing\u0026mdash;review and editing.\u003cstrong\u003e\u0026nbsp;Paul Wambua:\u0026nbsp;\u003c/strong\u003eresources, writing\u0026mdash;review and editing, supervision, and funding acquisition.\u003cstrong\u003e\u0026nbsp;David Njuguna Githinji:\u0026nbsp;\u003c/strong\u003eresources, validation, writing\u0026mdash;review and editing, supervision, and funding acquisition.\u003cstrong\u003e\u0026nbsp;Samson Rwahwire:\u0026nbsp;\u003c/strong\u003eresources, validation, writing\u0026mdash;review and editing, supervision, and funding acquisition.\u003cstrong\u003e\u0026nbsp;Ocident Bongomin:\u0026nbsp;\u003c/strong\u003ewriting and editing the revised manuscript, methodology, visualization, writing\u0026mdash;review and editing, validation, and formal analysis.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eVenkatraman P, Scott K (2018) Investigation of bark cloth for its surface texture and durability for apparel applications. \u003cem\u003eThe 91st Textile Institute World Conference, 23 July \u0026ndash;26 July 2018, Leeds, UK\u003c/em\u003e 1\u0026ndash;16 (2018)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRwawiire S, Tomkova B (2014) Thermo-physiological and comfort properties of Ugandan barkcloth from Ficus natalensis. J Text Inst 105:648\u0026ndash;653\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakirulu E, BARK CLOTH (2013) Swedish consumer attitudes towards sustainable fabrics. Fac Swed School Textiles Univ Boras\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWorden S (2016) Tradition and Transition: The changing fortunes of barkcloth in Uganda. \u003cem\u003eTextile Society of America Symposium Proceedings. 1012\u003c/em\u003e 596\u0026ndash;606\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRwawiire S, Luggya GW, Tomkova B, Morphology (2013) Thermal, and Mechanical Characterization of Bark Cloth from Ficus natalensis. \u003cem\u003eISRN Textiles\u003c/em\u003e 1\u0026ndash;8 (2013)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQueiroz HFM, De, Banea MD, Cavalcanti DK (2021) K. Adhesively bonded joints of jute, glass and hybrid jute / glass fibre reinforced polymer composites for automotive industry. Appl Adhes Sci. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s40563-020-00131-6\u003c/span\u003e\u003cspan address=\"10.1186/s40563-020-00131-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePe\u0026ccedil;as P, Carvalho H, Salman H, Leite M (2018) Natural Fibre Composites and Their Applications: A Review. J Compos Sci 1\u0026ndash;20. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/jcs2040066\u003c/span\u003e\u003cspan address=\"10.3390/jcs2040066\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePalanisamy S, Kalimuthu M, Nagarajan R, Fernandes Marlet JM, Santulli C, Physical (2023) Chemical, and Mechanical Characterization of Natural Bark Fibers (NBFs) Reinforced Polymer Composites: A Bibliographic Review. Fibers\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSelvaraj M, Pannirselvam N, Ravichandran PT, Bhuvaneshwaran M, Samson S (2023) Extraction and Characterization of a New Natural Cellulosic Fiber from Bark of Ficus Carica Plant as Potential Reinforcement for Polymer Composites. J Nat Fibers 20\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaravanakumar SS, Kumaravel A, Nagarajan T, Sudhakar P, Baskaran R (2013) Characterization of a novel natural cellulosic fiber from Prosopis juliflora bark. Carbohydr Polym 92:1928\u0026ndash;1933\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdesina OT, Jamiru T, Sadiku ER, Ogunbiyi OF, Beneke L (2019) Mechanical evaluation of hybrid natural fibre \u0026ndash; reinforced polymeric composites for automotive bumper beam: a review. Int J Adv Manuf Technol\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThyavihalli Girijappa GY, Rangappa SM, Parameswaranpillai J, Siengchin S (2019) Natural Fibers as Sustainable and Renewable Resource for Development of Eco-Friendly Composites: A Comprehensive Review. Front Mater 6:1\u0026ndash;14\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBichang DO, Aramide FO, Oladele IO, Alabi OO (2022) A Review on the Parameters Affecting the Mechanical, Physical, and Thermal Properties of Natural / Synthetic Fibre Hybrid. \u003cem\u003eAdvances in Materials Science and Engineering\u003c/em\u003e (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBakhori Mohd SN et al (2022) Physical, Mechanical and Perforation Resistance of Natural-Synthetic Fiber Interply Laminate Hybrid Composites. \u003cem\u003ePolymers (Basel)\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKudva A, Gt M, K DP, Physical (2022) thermal, mechanical, sound absorption and vibration damping characteristics of natural fiber reinforced composites and hybrid fiber reinforced composites : A review and vibration damping characteristics of natural fiber reinforced composites and hybrid fiber reinforced composites : A review. \u003cem\u003eCogent Eng\u003c/em\u003e 9\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSahu V, Bisen KS, Krishna M (2015) Mechanical Properties of Sisal and Pineapple Fiber Hybrid Composites Reinforced With Epoxy Resin. Int J Mod Eng Res 5:32\u0026ndash;38\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKumar A, Harendra S, Narang K, Bhattacharya S (2020) Mechanical properties of hybrid polymer composites: a review. J Brazilian Soc Mech Sci Eng. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40430-020-02517-w\u003c/span\u003e\u003cspan address=\"10.1007/s40430-020-02517-w\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGon D, Das K, Paul P, Maity S (2012) Jute Composites as Wood Substitute. Int J Text Sci 1:84\u0026ndash;93\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSalman SD, Leman Z, Sultan MTH, Ishak MR, Cardona F (2015) Hybrid Composites: A Review. Bio Resour 10:8580\u0026ndash;8603\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSathishkumar TP, Naveen J, Satheeshkumar S (2014) Hybrid fiber reinforced polymer composites \u0026ndash; A review. J Reinf Plast Compos 33\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJagannatha TD, Harish G (2015) Mechanical properties of carbon / glass fiber reinforced epoxy hybrid polymer composites. Int J Mech Eng Rob Res 4:131\u0026ndash;137\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAtiqah A, Chandrasekar M, Kumar TSM, Senthilkumar K, Ansari MNM (2019) Characterization and Interface of Natural and Synthetic Hybrid Composites Characterization and Interface of Natural and Synthetic Hybrid Composites. Encyclopedia of Renewable and Sustainable Materials. Elsevier Ltd.. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/B978-0-12-803581-8.10805-7\u003c/span\u003e\u003cspan address=\"10.1016/B978-0-12-803581-8.10805-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJawaid M, Khalil HPS (2015) A. Cellulosic / synthetic fibre reinforced polymer hybrid composites: A review. Carbohydr Polym 86:1\u0026ndash;18\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVenkateshwaran N, Elayaperumal A, Sathiya GK, Composites (2012) Part B Prediction of tensile properties of hybrid-natural fiber composites. Compos Part B 43:793\u0026ndash;796\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAmico SC, Carvalho LH, Odila M, Cioffi H (2014) Hybrid Vegetable / Glass Fiber Composites. Lignocellulosic Polym Compos 63\u0026ndash;82. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/9781118773949.ch4\u003c/span\u003e\u003cspan address=\"10.1002/9781118773949.ch4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSanthanam V, Dhanaraj R, Chandrasekaran M, Venkateshwaran N, Baskar S (2020) Experimental investigation on the mechanical properties of woven hybrid fiber reinforced epoxy composite. Mater Today Proc. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.matpr.2020.07.444\u003c/span\u003e\u003cspan address=\"10.1016/j.matpr.2020.07.444\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSelver E, Ucar N, Gulmez T (2017) Effect of stacking sequence on tensile, flexural and thermomechanical properties of hybrid flax / glass and jute / glass thermoset composites. J Ind Text 0:1\u0026ndash;27\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSanjay MR et al (2018) Characterization and properties of natural fiber polymer composites: A comprehensive review. \u003cem\u003eJournal of Cleaner Production\u003c/em\u003e vol. 172 Preprint at \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2017.10.101\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2017.10.101\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRangappa SM, Siengchin S, Parameswaranpillai J, Jawaid M, Ozbakkaloglu T (2022) Lignocellulosic fiber reinforced composites: Progress, performance, properties, applications, and future perspectives. \u003cem\u003ePolymer Composites\u003c/em\u003e vol. 43 Preprint at \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/pc.26413\u003c/span\u003e\u003cspan address=\"10.1002/pc.26413\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRwawiire S, Tomkova B, Militky J, Kale BM, Prucha P (2015) Effect of Layering Pattern on the Mechanical Properties of Bark Cloth (Ficus natalensis) Epoxy Composites. Int J Polym Anal Charact 20:160\u0026ndash;171\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRwawiire S et al (2016) Short-term creep of barkcloth reinforced laminar epoxy composites. Compos Part B 103:131\u0026ndash;138\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVelmurugan G et al (2024) Experimental investigation of mechanical and erosion properties of twill E-glass/sisal fiber reinforced hybrid polymer composite. Mater Today Proc. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/J.MATPR.2024.03.032\u003c/span\u003e\u003cspan address=\"10.1016/J.MATPR.2024.03.032\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAyyanar CB, Marimuthu K, Helaili S (2024) Experimental evaluation and numerical comparisons of pine tree leaves, graphene oxide loaded, and E-glass fiber reinforced sandwich composites. Int J Polym Anal Charact 29:363\u0026ndash;384\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBharath KN et al (2019) Effect of stacking sequence on properties of coconut leaf sheath/jute/E-glass reinforced phenol formaldehyde hybrid composites. J Ind Text 49\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eArpitha GR, Sanjay MR, Senthamaraikannan P, Barile C, Yogesha B (2017) Hybridization effect of sisal/glass/epoxy/filler based woven fabric reinforced composites. Exp Tech 41\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaich G et al (2015) Acacia bark residues as filler in polypropylene composites. Pol\u0026iacute;meros 25:289\u0026ndash;295\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHabib F (2024) Effect of Weight Fractions in Composite of Melinjo Stem Bark Fiber (Gnetum Gnemon). Am J Eng Res 13:147\u0026ndash;153\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePalanisamy S et al (2023) Tailoring Epoxy Composites with Acacia caesia Bark Fibers: Evaluating the Effects of Fiber Amount and Length on Material Characteristics. \u003cem\u003efibers\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClaude Martin YN, Koubaa A, Cloutier A, Soulounganga P, Wolcott M (2010) Effect of bark fiber content and size on the mechanical properties of bark / HDPE composites. Compos Part A 41:131\u0026ndash;137\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSanjay M, Yogesha B (2017) Studies on hybridization effect of jute / kenaf / E-glass woven fabric epoxy composites for potential applications: Effect of laminate stacking sequences. J Ind Text 0:1\u0026ndash;19\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePawar US, Chavan SS, Mohite DD (2024) Synthesis of glass FRP natural fiber hybrid composites (NFHC) and its mechanical characterization. Discover Sustain. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s43621-024-00231-4\u003c/span\u003e\u003cspan address=\"10.1007/s43621-024-00231-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAsma B, Hamdi L, Ali B, Youcef M (2020) Flexural Mechanical Properties of Natural Fibre Reinforced Polymer Composites - A Statistical Investigation. \u003cem\u003eFibers and Polymers\u003c/em\u003e 21, 2321\u0026ndash;2337 (2020)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKarimzadeh A, Yahya MY, Abdullah MN, Wong KJ (2020) Effect of Stacking Sequence on Mechanical Properties and Moisture Absorption Characteristic of Hybrid PALF / Glass Fiber Composites. Fibers Polym 21:1583\u0026ndash;1593\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEl-baky MAA, Megahed M, El-saqqa HH, Amal EA (2019) Mechanical Properties Evaluation of Sugarcane Bagasse-Glass / Polyester Composites. J Nat Fibers 00:1\u0026ndash;18\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrabhu R et al (2017) Fabrication and Analysis of Jute, Glass and Flax Hybrid Composites Using Rice Husk Charcoal as Filler Material. Am J Mater Sci 7:135\u0026ndash;139\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHanifawati IN, Azmah H, Sapuan MA, S. M., Zainudin ES (2011) Tensile and Flexural Behavior of Hybrid Banana Pseudostem/Glass Fibre Reinforced Polyester Composites. Key Eng Mater 471\u0026ndash;472:686\u0026ndash;691\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBindal A, Singh S, Batra NK, Khanna R (2013) Development of Glass/Jute Fibers Reinforced Polyester Composite. \u003cem\u003eIndian Journal of Materials Science\u003c/em\u003e 1\u0026ndash;6 (2013)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHashim MKR, Majid MSA, Jamir MRM, Kasim FH, Sultan MTH (2021) The effect of stacking sequence and ply orientation on the mechanical properties of pineapple leaf fibre (Palf)/carbon hybrid laminate composites. Polym (Basel) 13:1\u0026ndash;24\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDoğan MA, Gemi L, Yazman Ş, Ceritbinmez F, Yapici A (2024) Effect of hybridization and stacking sequence on damage development in AWJ machining of Al/FRP/Al FML composites. J Manuf Process 131:141\u0026ndash;159\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMahmud SH et al (2024) Fabrication and mechanical performance investigation of jute/glass fiber hybridized polymer composites: Effect of stacking sequences. Next Mater 5:100236\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUmar bin, Ashraf M et al (2024) Effect of fibre hybridization and stacking sequence on the low velocity impact response of flax/basalt/aluminum composite-metal joints. Compos Struct 331:117925\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDalbehera S, Acharya SK (2014) Study on mechanical properties of natural fiber reinforced woven jute-glass hybrid epoxy composites. Adv Polym Sci Technol 4:1\u0026ndash;6\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAltaee MA, Mostafa NH (2023) Mechanical properties of interply and intraply hybrid laminates based on jute glass / epoxy composites. J Eng Appl Sci 1\u0026ndash;30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s44147-023-00293-7\u003c/span\u003e\u003cspan address=\"10.1186/s44147-023-00293-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShahzad A, Nasir SU (2017) \u003cem\u003eMechanical Properties of Natural Fiber / Synthetic Fiber Reinforced Polymer Hybrid Composites Mechanical Properties\u003c/em\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/978-3-319-46610-1\u003c/span\u003e\u003cspan address=\"10.1007/978-3-319-46610-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRachchh NV, Trivedi DN (2018) Mechanical Characterization and Vibration Analysis of Hybrid E-glass / Bagasse Fiber Polyester Composites. Mater Today Proc 5:7692\u0026ndash;7700\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMisri S, Leman Z, Sapuan SM, Ishak MR (2010) Mechanical properties and fabrication of small boat using woven glass / sugar palm fibres reinforced unsaturated polyester hybrid composite. IOP Conf Ser Mater Sci Eng 11:1\u0026ndash;13\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHemalatha S, Ramesha N (2014) Tensile Properties of Natural Fiber-Reinforced Epoxy-Hybrid Composites. Indian J Adv Chem Sci 2:24\u0026ndash;27\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKumar A, Singh S (2013) Analysis of mechanical properties and cost of glass/jute fiber-reinforced hybrid polyester composites. J Materials: Des Appl 0:1\u0026ndash;7\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKumar SS (2020) Effect of Natural Fiber Loading on Mechanical Properties and Thermal Characteristics of Hybrid Polyester Composites for Industrial and Construction Fields. \u003cem\u003eFibers and Polymers\u003c/em\u003e 21, 1508\u0026ndash;1514 (2020)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMohanta N, Acharya SK (2014) Investigation of mechanical properties of luffa cylindrica fibre reinforced epoxy hybrid composite. Int J Eng Sci Technol 7:1\u0026ndash;10\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Moi University","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Bark cloth, Glass fiber, Hybrid composites, Polyester resin, Mechanical properties, Stacking sequence","lastPublishedDoi":"10.21203/rs.3.rs-5990257/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5990257/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigates the mechanical properties of hybrid composites reinforced with bark cloth (\u003cem\u003eFicus natalensis\u003c/em\u003e) and glass fiber in a polyester resin matrix. Composites were fabricated using the hand layup technique with varying fiber weight fractions (15%, 20%, and 25%) and hybrid ratios (3:1, 2:2, 1:3). The influence of hybrid ratio and stacking sequence on flexural, tensile, compressive, and impact strengths was evaluated. Results indicated that composites with higher glass fiber content exhibited superior mechanical performance, with optimal flexural (140.94 MPa), tensile (43.24 MPa), compressive (26.47 MPa), and impact strengths (32.44 kJ/m\u0026sup2;) at a 1:3 hybrid ratio. Hybridization improved the mechanical properties of the composites, particularly flexural strength, which was significantly affected by stacking sequence. These findings suggest that bark cloth/glass fiber hybrid composites have potential for applications in automotive and structural industries.\u003c/p\u003e","manuscriptTitle":"Fabrication and mechanical performance of bark cloth/glass fiber reinforced hybrid polymer composites for automotive applications","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-15 15:54:49","doi":"10.21203/rs.3.rs-5990257/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9b5ae7dd-3c08-45f1-84dd-acb698dd8af7","owner":[],"postedDate":"February 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":44051064,"name":"Materials Engineering"}],"tags":[],"updatedAt":"2025-02-15T15:54:49+00:00","versionOfRecord":[],"versionCreatedAt":"2025-02-15 15:54:49","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5990257","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5990257","identity":"rs-5990257","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}