Mechanical and Microstructural Optimization of Hybrid Epoxy Composites with Renewable Bambara Nut Shells and Potato Starch Reinforcement

Mechanical and Microstructural Optimization of Hybrid Epoxy Composites with Renewable Bambara Nut Shells and Potato Starch Reinforcement | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Mechanical and Microstructural Optimization of Hybrid Epoxy Composites with Renewable Bambara Nut Shells and Potato Starch Reinforcement Chidume N. Nwambu, Victor U. Okpechi, Ogechukwu B. Aribodor, Chilee M. Ekwedigwe, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5689417/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The increasing demand for sustainable materials has driven research into bio-agricultural waste as a reinforcement for hybrid composites. This study investigates the mechanical and morphological properties of hybrid epoxy composites reinforced with Bambara nutshell and potato starch particles. Composite samples were produced with varying reinforcement loadings (5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, and 30 wt%) and tested according to ASTM standards. Results show that tensile and flexural strengths increased significantly with reinforcement up to 25 wt%, achieving maximum values of 62.38 MPa and 84.21 MPa, respectively, due to optimal filler-matrix interaction. Beyond 25 wt%, strength properties declined because of poor wettability and filler agglomeration. Impact strength peaked at 5 wt% reinforcement with a value of 0.372 J/mm, but decreased at higher loadings due to increased brittleness. Microstructural analysis revealed that the improved performance at 25 wt% was attributed to better dispersion, fewer voids, and strong filler-matrix adhesion. These findings highlight the potential of utilizing agricultural waste to produce eco-friendly hybrid composites, contributing to sustainable materials development, reducing reliance on synthetic alternatives, and offering significant advantages for industrial and residential applications where lightweight materials with superior impact and tensile properties are required. Renewable Resources Bambara nut shells potato starch cellulose hybrid composites tensile strength bio-agricultural waste Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Biocomposites are composite materials composed of biopolymers (e.g., starch, cellulose, proteins) and reinforcements (e.g., fibers, particles). This combination yields materials with improved mechanical, thermal, and barrier properties [ 1 – 4 ]. The growing interest in biocomposites stems from their potential to replace traditional synthetic composites, which are often non-biodegradable and derived from fossil fuels [ 3 , 14 ]. Biocomposite materials have their potential to improve sustainability, utilize abundant biomass resources and lower carbon footprint. Provide new economic opportunities, create new industries and jobs diversify agricultural revenue streams. Potential applications of biocomposites include: packaging materials (e.g., biodegradable packaging, disposable cutlery), the automotive industry (e.g., interior components, biocomposite fibers), construction materials (e.g., insulation, roofing, biocomposite panels), biomedical applications (e.g., implantable devices, drug delivery systems), consumer products (e.g., biodegradable plastics, sustainable textiles) [ 5 – 12 ]. Developing biocomposites from potato starch and Bambara nut shell cellulose could lead to innovative, sustainable materials for various industries, contributing to a more circular and environmentally friendly economy [ 14 ]. Conventional composites, often made from non-renewable resources and non-biodegradable materials, contribute to environmental concerns such as pollution, waste accumulation, and carbon footprint. In contrast, biocomposites offer a promising solution by utilizing renewable resources, reducing dependence on fossil fuels, and providing biodegradability [ 1 , 8 , 10 ]. Potato starch, a readily available and biodegradable polymer, has shown potential as a biocomposite component. Bambara nut shell, an agricultural waste product, offers a unique opportunity for valorization as a reinforcement material. The combination of potato starch and Bambara nut shell cellulose may lead to the development of a sustainable biocomposite with improved properties [ 11 , 15 ]. Despite the growing interest in biocomposites, traditional synthetic reinforcements (e.g., glass fibers, carbon fibers) dominate the market. However, these materials have significant environmental and health impacts, including non-renewable resources, high energy consumption during production, toxic chemicals and emissions, and difficulty in recycling and disposal [ 7 ]. However, natural fibers also have limitations, such as lower mechanical properties compared to synthetic fibers, higher moisture absorption and sensitivity to humidity, and limited standardization and quality control. The challenge lies in overcoming these limitations and harnessing the potential of natural fibers to create high-performance biocomposites that can compete with traditional materials [ 11 – 16 ]]. By reinforcing potato starch with Bambara nut shell cellulose, this research aims to examine the structure and mechanical properties and contribute to the development of sustainable, high-performance biocomposites for various industrial applications. Experimental Procedure High grade epoxy resin and hardener were procured from Patolinks, located in Onitsha, Nigeria while the bambara nut shells and potatoes starch were sourced locally from Eke-Awka Market at Awka, Nigeria. The nitric acid and sodium hydroxide for chemical treatment were sourced from Ifeco Chemical Nig. Ltd, Bridge Head Market Onitsha, Nigeria. The fibre extraction was conducted manually in line with the previous studies which reported that manually extracted fibres exhibit higher fibre density qualities than chemically extracted fibres [ 17 ]. The hybrid composites were prepared through the following procedure. The Bambara in its raw state was boiled to a temperature above 100 o c, after which the seeds were then separated from the shells. To reduce the moisture content, the shells were dried for 3hrs before treating the fibre with sodium hydroxide. The Bambara nutshell was immersed in a 6% sodium hydroxide solution for a whole day to treat the fibre. After which was allowed to sun dry for a total period of 72 hours given the weather conditions. The fibre was then reduced to particulates of 0.75µm, with the aid of grinding machine, this was done to achieve compatibility with the potatoes' starch cellulose. Potatoes starch was extracted from the sweet potatoes gotten from the market, in such a way that the result was a fine powder of equally 0.75µm. The potatoes in their raw state were washed with distilled water to remove impurities from the composite, with a hand cutter, the potatoes were neatly peeled to reveal an inner layer. The potatoes were then marched with cold water below 30 o c, the resulting composition was then separated with the aid of a sieve and left undisturbed for 1 hour. The liquid is then separated, revealing a whitish layer comprising the starch content needed (Fig. 1 a and b). The starch is then allowed to cake, after which is been dried and screened to get the result needed in a powdered form. Mechanical analysis of the developed composites The tensile strength measurements were performed on a testometric testing machine at the Anambra State Materials Testing Laboratory, Nigeria. The composite samples were 160mm×19mm× 3.2mm in dimension in accordance with ASTM 638 − 10 standard test method for tensile properties of the polymer. The tests were performed at a constant strain rate of 0.5mm/min. the maximum tensile strength was calculated in accordance with the equation: $$\:Rt=\frac{Pmax}{Bd}$$ 1.0 Where, B = width of reduced cross section of the specimen measured in dry conditioning (mm), D = thickness of the specimen measured in dry condition, Pmax = maximum tensile load (N), R t = maximum tensile stress (MPa). The impact strength testing of the composite samples was conducted using Avery dension test machine at the Anambra state materials testing laboratory, Nigeria. Charpy impact tests was conducted on the samples with 100mm ×19mm ×3.2mm dimension in accordance with ASTM D256-10 standard test method for determining the chary pendulum impact resistance of plastics. Flexural strength test were conducted according to ASTM Standard D7264, a three-point bending test was done by evaluating the flexural strength with dimensions 300 x 19 x 3.2 mm. The universal testing machine at Anambra state materials testing laboratory, Nigeria, was used to perform the bending test. Load versus displacement data extracted from the universal testing machine was used to determine the stresses and the strains during loading, using equations (2.0) and (3.0) σ = 3PL(2 bh 2 ) (2.0) Where σ = Stress (MPa), P = Force applied (N), L = length of supporting span, b = beam breadth, h = beam thickness. ϵ=6δ h L 2 (3.0) ϵ=strain, δ = deflection at mid-span, L = length of supporting span, h = beam breadth. Results and Discussion Figures 2 and 3 display the tensile and flexural behavior results of the produced composites at different reinforcing loadings. The unreinforced sample (sample SP1) and the reinforced composite samples were found to have significantly higher tensile strengths. Tensile strength increased gradually from 5wt% to 30wt% reinforcement loading. Adding bambara shell and potato starch nanostructured reinforcements drastically increased the epoxy matrix's tensile strength, rising from roughly 27 MPa to 61 MPa, or 54wt%. According to Eze et al. [ 17 ], the Bambara shell's capacity for reinforcement and the filler-matrix interaction's high quality are the reasons for this observed increase. It could be deduced therefore that at 54 wt% reinforcement loading, there was a good transfer of load between the reinforcement and the matrix. It can also be seen clearly that at reinforcement loading above 54 wt% the tensile strength dropped very significantly due to the inability of the matrix to wet the reinforcement at higher loading. Consequently, the matrix cannot transfer load effectively to the reinforcement. Furthermore, with higher reinforcement loading fiber agglomeration becomes nearly unavoidable due to poor wettability, during loading the composite is certain to fail at the regions of high-stress concentration generated by agglomerated reinforcements. Similar findings have been reported in several epoxy nanofiber-reinforced composite papers [ 2 – 6 ]. The composites cannot sustain large loads over the ideal dispersion level, which is 54 weight percent. This holds for micro-size reinforcement as well as nano-size reinforcement [ 4 , 6 ]. Although the type and nature of reinforcement have a significant impact on tensile strength, the general trend is that tensile strength will decline beyond the volume of reinforcement that the matrix can support. Composite samples with the lowest reinforcement content had the highest impact strength as presented in Fig. 4 ; it was found that impact strength decreases with increasing reinforcement content. Nevertheless, the reinforced samples outperformed the unreinforced composite sample made entirely of epoxy resin. This observation aligns with the research finding of Eze et al. [ 17 ] on the mechanical properties of epoxy/Bambara nutshell composite. Microstructure analysis of the composite samples A scanning electron microscope was used to evaluate the fracture surfaces of reinforced composites at a magnification of X300. The results are shown in Figs. 5 a- 6 b. Using these numbers, The examination of the fractured surfaces of samples SP4 (20 wt%) and SP5 (25 wt%) of the epoxy composite reinforced with Bambara nutshell and potato starch reinforcement reveals that loading had a better reinforcement-matrix dispersion with fewer voids, less particle aggregation, and better adhesion of the epoxy matrix, which explained the improved properties and performance in comparison to other samples with large voids, which indicated areas of poor adhesion between reinforcement and matrix [ 4 , 6 ]. Additionally, samples SP5 (25 wt%) and SP4 (20 wt%) had fewer filler agglomerations than sample SP6 (30 weight percent), suggesting superior wettability at lower reinforcement. Lastly, there were no noticeable gaps on the sample SP5 fracture surfaces of the Bambara nutshell/potato starch composites, indicating a good mix during processing [ 4 ]. These corroborate the previous research showing that better bonding occurs with increasing grain size, improving the mechanical characteristics of the biocomposites [ 7 ]. Conclusion This project investigated the impact of potato starch and bambara nut shell particles on the mechanical and structural characteristics of epoxy composite. Utilizing bio-agricultural waste as reinforcement material for composite production is the goal of this study. Bio-agricultural waste is readily available and less expensive than synthetic resources like glass and carbon fibers, among others. It has been documented how the mechanical and morphological characteristics of the epoxy composite are affected by the plentiful bambara nutshell and potatoes in Africa. Within the range of the variations in this study, the optical properties of the composites were obtained at reinforcement loading up to 25 weight percent; tensile and flexural properties were observed to decrease above this reinforcement threshold load. The optimum tensile and flexural strength of 62.38 MPa and 84.21 MPa were obtained with 25 weight percent of the reinforcement; increasing the reinforcement loading to 30 weight percent resulted in a significant decrease in the strength performance. The results indicate that the amount of bambara nut shell fillers in the epoxy matrix has a significant impact on both mechanical and physical properties. Nevertheless, the maximum impact strength was achieved with only 5% reinforcement. Accordingly, the composite may find use in both industrial and residential settings at ideal reinforcement loading, particularly in situations where low weight, high impact energy, and good tensile strength are crucial considerations. Declarations Consent for Publication Not Applicable. All authors have approved the manuscript for publication. Availability of Data and Materials All relevant data supporting the findings of this study are included in the manuscript. Conflicts of Interest The authors declare no conflicts of interest in this research. Funding No funding was received for this study. Author Contributions C.N.N., V.U.O., O.B.A., and C.M.E. collaboratively developed the concept and designed the study methodology, including data collection methods. C.N.N., V.U.O., and C.M.E. jointly developed essential software tools for data analysis. O.B.A. and C.N.N. conducted literature searches, performed analysis and reporting, and drafted the initial manuscript with input from C.M.E. C.N.N. and J.T.N. were responsible for project administration and coordination. All authors contributed significantly to the work, reviewed drafts, and approved the final submitted version of the manuscript. References H.P.S. Abdul Khalil, H. M. Fizree, A.H. Bhat, M. Jawaid, C.K. Abdullah. Development and Characterization of Epoxy Nano-composites based on Nano-structured Oil Palm Ash, Composites: Part B, 53 (2013) 324-333 Achebe C, Chukwuneke J, Anene F, et al. A retrofit for asbestos based brake pad employing palm kernel fiber as the base filler material. Proc Inst Mech Eng Part L J Mater Des App 2019; 233: 906–1913. 12. M. I. Uzochukwu, W.U. Eze, P. Garba, M. I. Ugbaja, and H. Opara. Study on the Physico-Mechanical Properties of Treated Baobab Fiber (Adansonia Digitata) Nano-Filler/Epoxy Composite, Multiscale and Multidisciplinary Modelling, Experiments and Design 3 (2020) 151–159. https://doi.org/10.1007/s41939-020-00068-0 J. Y. Tong, R. R. N. Royan, Y. C. Ng, M. H. Ghani and S. Ahmad. Study of the Mechanical and Morphological Properties of Recycled HDPE Composite using Rice Husk Filler, Advances in Material Sciences and Engineering, (2014) Article ID 938961. https://doi. org/10.1155/2014/938961 S. Mudradi, P. Ravikanta, R. Kandavalli, and B. Thirumaleshwara. Effect of Filler Content on Performance of Epoxy/PTW Composites, Advances in Material Science and Engineering, (2014). https://doi.org/10.1155/2014/970468 T. S. George, A. Krishnan, R. Anjana, and K. E George. Effect of Maleic Anhydride Grafting on Nanokaolin Clay Reinforced Polystyrene/High Density Polyethylene Blends, Polymer Composites, 33 (2012) 1465 – 1472. S. Ojha, R. Gujjala and S. K. Acharya, Effect of Filler Loading on Mechanical and Tribological Properties of Wood Apple Shell Reinforced Epoxy Composite, Advances in Material Science and Engineering (2014). https://doi.org/10.1155/2014/538651 Adebisi A. A. and Maleque M. A. and Shah Q. H. (2011) Surface temperature distribution in a composite brake rotor. International Journal of Mechanical and Materials Engineering, 6 (3): 356-361. Aderiye J. (2014) Kaolin Mineral material for automotive ceramic brake pad manufacturing industry. International Journal of Technology Enhanancements and Emerging Engineering Research, Vol 2, Issue 3 ISSN 2347 – 4289. Ekwedigwe, C., Nwambu, C., Nnuka, E., Effects of rice straw fibre and walnut shell ash particulates on the mechanical behavior of epoxy composite. Unizik Journal of Engineering and Applied Sciences 1 (1), 69-77. Yawas D. S., Aku S. Y. and Amaren S. G. (2013) Morphology and properties of periwinkle shell asbestos-free brake pad. Journal of King Saud University- Engineering Sciences. Ekwedigwe, C., Nnakwo, K., Nwambu, C., Viscoelastic properties of alkaline treated walnut shell/rice straw fiber/epoxy biocomposite. Journal of Civil Engineering and Environmental Science, 9 (1), 009-013. Mohamed Khazal Hussain, et al. - Fabrication of epoxy composite material reinforced with bamboo fibers, Journal of Applied Engineering Science Vol. 19, No. 1, 2021. Kannan, R., Ahmad, M. (2013). A review on mechanical properties of bamboo fiber reinforced polymer composite. Australian Journal of Basic and Applied Sciences, vol. 7, no. 8, pp. 247–253. CN Nwambu, GI Chibueze, EN Nwankwo, CM Ekwedigwe, (2023) Taguchi analysis of the tensile behaviour of unaged and hygrothermally aged asymmetric helicoidally stacked CFRP composites, Journal of Civil Engineering and Environmental Sciences 9 (2), 068-072. C Nwambu, I Chibueze, K Iyebeye, C Ekwedigwe, (2023) Optimization of viscoelastic behaviors of bioinspired asymmetric helicoidal CFRP composites using Taguchi Method, Archive of Biomedical Science and Engineering 9 (1), 010-014. W. U. Eze , M. K. Yakubu, M. A. Buba, A. Kuzmin, I. B. Santos-Ndukwe, M. I. Ugbaja 1 and A. H. Bayero (2022) Effect of Nano-Structured Bambara Nut Shell (Vigna Subterranea (L.) Verdc) As Filler on the Physical, Mechanical and Morphological Properties of Epoxy Matrix. Journal of Materials and Environmental Science, Vol. 13, Issue 10, PP 1155-1170. 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-5689417","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":393340421,"identity":"8a1af819-8fb6-41a5-9e39-69e82aaa6769","order_by":0,"name":"Chidume N. 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This combination yields materials with improved mechanical, thermal, and barrier properties [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The growing interest in biocomposites stems from their potential to replace traditional synthetic composites, which are often non-biodegradable and derived from fossil fuels [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Biocomposite materials have their potential to improve sustainability, utilize abundant biomass resources and lower carbon footprint. Provide new economic opportunities, create new industries and jobs diversify agricultural revenue streams. Potential applications of biocomposites include: packaging materials (e.g., biodegradable packaging, disposable cutlery), the automotive industry (e.g., interior components, biocomposite fibers), construction materials (e.g., insulation, roofing, biocomposite panels), biomedical applications (e.g., implantable devices, drug delivery systems), consumer products (e.g., biodegradable plastics, sustainable textiles) [\u003cspan additionalcitationids=\"CR6 CR7 CR8 CR9 CR10 CR11\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Developing biocomposites from potato starch and Bambara nut shell cellulose could lead to innovative, sustainable materials for various industries, contributing to a more circular and environmentally friendly economy [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eConventional composites, often made from non-renewable resources and non-biodegradable materials, contribute to environmental concerns such as pollution, waste accumulation, and carbon footprint. In contrast, biocomposites offer a promising solution by utilizing renewable resources, reducing dependence on fossil fuels, and providing biodegradability [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Potato starch, a readily available and biodegradable polymer, has shown potential as a biocomposite component. Bambara nut shell, an agricultural waste product, offers a unique opportunity for valorization as a reinforcement material. The combination of potato starch and Bambara nut shell cellulose may lead to the development of a sustainable biocomposite with improved properties [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite the growing interest in biocomposites, traditional synthetic reinforcements (e.g., glass fibers, carbon fibers) dominate the market. However, these materials have significant environmental and health impacts, including non-renewable resources, high energy consumption during production, toxic chemicals and emissions, and difficulty in recycling and disposal [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, natural fibers also have limitations, such as lower mechanical properties compared to synthetic fibers, higher moisture absorption and sensitivity to humidity, and limited standardization and quality control. The challenge lies in overcoming these limitations and harnessing the potential of natural fibers to create high-performance biocomposites that can compete with traditional materials [\u003cspan additionalcitationids=\"CR12 CR13 CR14 CR15\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]]. By reinforcing potato starch with Bambara nut shell cellulose, this research aims to examine the structure and mechanical properties and contribute to the development of sustainable, high-performance biocomposites for various industrial applications.\u003c/p\u003e\n\u003ch3\u003eExperimental Procedure\u003c/h3\u003e\n\u003cp\u003eHigh grade epoxy resin and hardener were procured from Patolinks, located in Onitsha, Nigeria while the bambara nut shells and potatoes starch were sourced locally from Eke-Awka Market at Awka, Nigeria. The nitric acid and sodium hydroxide for chemical treatment were sourced from Ifeco Chemical Nig. Ltd, Bridge Head Market Onitsha, Nigeria. The fibre extraction was conducted manually in line with the previous studies which reported that manually extracted fibres exhibit higher fibre density qualities than chemically extracted fibres [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The hybrid composites were prepared through the following procedure. The Bambara in its raw state was boiled to a temperature above 100\u003csup\u003eo\u003c/sup\u003ec, after which the seeds were then separated from the shells. To reduce the moisture content, the shells were dried for 3hrs before treating the fibre with sodium hydroxide. The Bambara nutshell was immersed in a 6% sodium hydroxide solution for a whole day to treat the fibre. After which was allowed to sun dry for a total period of 72 hours given the weather conditions. The fibre was then reduced to particulates of 0.75\u0026micro;m, with the aid of grinding machine, this was done to achieve compatibility with the potatoes' starch cellulose. Potatoes starch was extracted from the sweet potatoes gotten from the market, in such a way that the result was a fine powder of equally 0.75\u0026micro;m.\u003c/p\u003e \u003cp\u003eThe potatoes in their raw state were washed with distilled water to remove impurities from the composite, with a hand cutter, the potatoes were neatly peeled to reveal an inner layer. The potatoes were then marched with cold water below 30\u003csup\u003eo\u003c/sup\u003ec, the resulting composition was then separated with the aid of a sieve and left undisturbed for 1 hour. The liquid is then separated, revealing a whitish layer comprising the starch content needed (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea and b). The starch is then allowed to cake, after which is been dried and screened to get the result needed in a powdered form.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMechanical analysis of the developed composites\u003c/h2\u003e \u003cp\u003eThe tensile strength measurements were performed on a testometric testing machine at the Anambra State Materials Testing Laboratory, Nigeria. The composite samples were 160mm\u0026times;19mm\u0026times; 3.2mm in dimension in accordance with ASTM 638\u0026thinsp;\u0026minus;\u0026thinsp;10 standard test method for tensile properties of the polymer. The tests were performed at a constant strain rate of 0.5mm/min. the maximum tensile strength was calculated in accordance with the equation:\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:Rt=\\frac{Pmax}{Bd}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1.0\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere, B\u0026thinsp;=\u0026thinsp;width of reduced cross section of the specimen measured in dry conditioning (mm), D\u0026thinsp;=\u0026thinsp;thickness of the specimen measured in dry condition, Pmax\u0026thinsp;=\u0026thinsp;maximum tensile load (N), R\u003csub\u003et\u003c/sub\u003e = maximum tensile stress (MPa).\u003c/p\u003e \u003cp\u003eThe impact strength testing of the composite samples was conducted using Avery dension test machine at the Anambra state materials testing laboratory, Nigeria. Charpy impact tests was conducted on the samples with 100mm \u0026times;19mm \u0026times;3.2mm dimension in accordance with ASTM D256-10 standard test method for determining the chary pendulum impact resistance of plastics.\u003c/p\u003e \u003cp\u003eFlexural strength test were conducted according to ASTM Standard D7264, a three-point bending test was done by evaluating the flexural strength with dimensions 300 x 19 x 3.2 mm. The universal testing machine at Anambra state materials testing laboratory, Nigeria, was used to perform the bending test. Load versus displacement data extracted from the universal testing machine was used to determine the stresses and the strains during loading, using equations (2.0) and (3.0)\u003c/p\u003e \u003cp\u003eσ\u0026thinsp;=\u0026thinsp;3PL(2\u003cem\u003ebh\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e) (2.0)\u003c/p\u003e \u003cp\u003eWhere σ\u0026thinsp;=\u0026thinsp;Stress (MPa), P\u0026thinsp;=\u0026thinsp;Force applied (N), L\u0026thinsp;=\u0026thinsp;length of supporting span, \u003cem\u003eb\u003c/em\u003e\u0026thinsp;=\u0026thinsp;beam breadth, \u003cem\u003eh\u003c/em\u003e\u0026thinsp;=\u0026thinsp;beam thickness.\u003c/p\u003e \u003cp\u003eϵ=6δ\u003cem\u003eh\u003c/em\u003eL\u003csup\u003e2\u003c/sup\u003e (3.0)\u003c/p\u003e \u003cp\u003eϵ=strain, δ\u0026thinsp;=\u0026thinsp;deflection at mid-span, L\u0026thinsp;=\u0026thinsp;length of supporting span, \u003cem\u003eh\u003c/em\u003e\u0026thinsp;=\u0026thinsp;beam breadth.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eFigures \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e display the tensile and flexural behavior results of the produced composites at different reinforcing loadings. The unreinforced sample (sample SP1) and the reinforced composite samples were found to have significantly higher tensile strengths. Tensile strength increased gradually from 5wt% to 30wt% reinforcement loading. Adding bambara shell and potato starch nanostructured reinforcements drastically increased the epoxy matrix\u0026apos;s tensile strength, rising from roughly 27 MPa to 61 MPa, or 54wt%. According to Eze et al. [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e], the Bambara shell\u0026apos;s capacity for reinforcement and the filler-matrix interaction\u0026apos;s high quality are the reasons for this observed increase. It could be deduced therefore that at 54 wt% reinforcement loading, there was a good transfer of load between the reinforcement and the matrix. It can also be seen clearly that at reinforcement loading above 54 wt% the tensile strength dropped very significantly due to the inability of the matrix to wet the reinforcement at higher loading. Consequently, the matrix cannot transfer load effectively to the reinforcement.\u003c/p\u003e\n\u003cp\u003eFurthermore, with higher reinforcement loading fiber agglomeration becomes nearly unavoidable due to poor wettability, during loading the composite is certain to fail at the regions of high-stress concentration generated by agglomerated reinforcements. Similar findings have been reported in several epoxy nanofiber-reinforced composite papers [\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e]. The composites cannot sustain large loads over the ideal dispersion level, which is 54 weight percent. This holds for micro-size reinforcement as well as nano-size reinforcement [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e]. Although the type and nature of reinforcement have a significant impact on tensile strength, the general trend is that tensile strength will decline beyond the volume of reinforcement that the matrix can support. Composite samples with the lowest reinforcement content had the highest impact strength as presented in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e; it was found that impact strength decreases with increasing reinforcement content. Nevertheless, the reinforced samples outperformed the unreinforced composite sample made entirely of epoxy resin. This observation aligns with the research finding of Eze et al. [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e] on the mechanical properties of epoxy/Bambara nutshell composite.\u003c/p\u003e\n\u003ch3\u003eMicrostructure analysis of the composite samples\u003c/h3\u003e\n\u003cp\u003eA scanning electron microscope was used to evaluate the fracture surfaces of reinforced composites at a magnification of X300. The results are shown in Figs. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea-\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb.\u003c/p\u003e\n\u003cp\u003eUsing these numbers, The examination of the fractured surfaces of samples SP4 (20 wt%) and SP5 (25 wt%) of the epoxy composite reinforced with Bambara nutshell and potato starch reinforcement reveals that loading had a better reinforcement-matrix dispersion with fewer voids, less particle aggregation, and better adhesion of the epoxy matrix, which explained the improved properties and performance in comparison to other samples with large voids, which indicated areas of poor adhesion between reinforcement and matrix [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e]. Additionally, samples SP5 (25 wt%) and SP4 (20 wt%) had fewer filler agglomerations than sample SP6 (30 weight percent), suggesting superior wettability at lower reinforcement. Lastly, there were no noticeable gaps on the sample SP5 fracture surfaces of the Bambara nutshell/potato starch composites, indicating a good mix during processing [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e]. These corroborate the previous research showing that better bonding occurs with increasing grain size, improving the mechanical characteristics of the biocomposites [\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis project investigated the impact of potato starch and bambara nut shell particles on the mechanical and structural characteristics of epoxy composite. Utilizing bio-agricultural waste as reinforcement material for composite production is the goal of this study. Bio-agricultural waste is readily available and less expensive than synthetic resources like glass and carbon fibers, among others. It has been documented how the mechanical and morphological characteristics of the epoxy composite are affected by the plentiful bambara nutshell and potatoes in Africa. Within the range of the variations in this study, the optical properties of the composites were obtained at reinforcement loading up to 25 weight percent; tensile and flexural properties were observed to decrease above this reinforcement threshold load. The optimum tensile and flexural strength of 62.38 MPa and 84.21 MPa were obtained with 25 weight percent of the reinforcement; increasing the reinforcement loading to 30 weight percent resulted in a significant decrease in the strength performance. The results indicate that the amount of bambara nut shell fillers in the epoxy matrix has a significant impact on both mechanical and physical properties.\u003c/p\u003e \u003cp\u003eNevertheless, the maximum impact strength was achieved with only 5% reinforcement. Accordingly, the composite may find use in both industrial and residential settings at ideal reinforcement loading, particularly in situations where low weight, high impact energy, and good tensile strength are crucial considerations.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;Not Applicable.\u003cbr\u003e\u0026nbsp;All authors have approved the manuscript for publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of Data and Materials\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;All relevant data supporting the findings of this study are included in the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;The authors declare no conflicts of interest in this research.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;No funding was received for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eC.N.N., V.U.O., O.B.A., and C.M.E. collaboratively developed the concept and designed the study methodology, including data collection methods. C.N.N., V.U.O., and C.M.E. jointly developed essential software tools for data analysis. O.B.A. and C.N.N. conducted literature searches, performed analysis and reporting, and drafted the initial manuscript with input from C.M.E. C.N.N. and J.T.N. were responsible for project administration and coordination. All authors contributed significantly to the work, reviewed drafts, and approved the final submitted version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eH.P.S. Abdul Khalil, H. M. Fizree, A.H. Bhat, M. Jawaid, C.K. Abdullah. Development and Characterization of Epoxy Nano-composites based on Nano-structured Oil Palm Ash, Composites: Part B, 53 (2013) 324-333\u003c/li\u003e\n\u003cli\u003eAchebe C, Chukwuneke J, Anene F, et al. A retrofit for asbestos based brake pad employing palm kernel fiber as the base filler material. Proc Inst Mech Eng Part L J Mater Des App 2019; 233: 906\u0026ndash;1913. 12. \u003c/li\u003e\n\u003cli\u003eM. I. Uzochukwu, W.U. Eze, P. Garba, M. I. Ugbaja, and H. Opara. Study on the Physico-Mechanical Properties of Treated Baobab Fiber (Adansonia Digitata) Nano-Filler/Epoxy Composite, Multiscale and Multidisciplinary Modelling, Experiments and Design 3 (2020) 151\u0026ndash;159. https://doi.org/10.1007/s41939-020-00068-0\u003c/li\u003e\n\u003cli\u003eJ. Y. Tong, R. R. N. Royan, Y. C. Ng, M. H. Ghani and S. Ahmad. Study of the Mechanical and Morphological Properties of Recycled HDPE Composite using Rice Husk Filler, Advances in Material Sciences and Engineering, (2014) Article ID 938961. https://doi. org/10.1155/2014/938961\u003c/li\u003e\n\u003cli\u003eS. Mudradi, P. Ravikanta, R. Kandavalli, and B. Thirumaleshwara. Effect of Filler Content on Performance of Epoxy/PTW Composites, Advances in Material Science and Engineering, (2014). https://doi.org/10.1155/2014/970468\u003c/li\u003e\n\u003cli\u003eT. S. George, A. Krishnan, R. Anjana, and K. E George. Effect of Maleic Anhydride Grafting on Nanokaolin Clay Reinforced Polystyrene/High Density Polyethylene Blends, Polymer Composites, 33 (2012) 1465 \u0026ndash; 1472.\u003c/li\u003e\n\u003cli\u003eS. Ojha, R. Gujjala and S. K. Acharya, Effect of Filler Loading on Mechanical and Tribological Properties of Wood Apple Shell Reinforced Epoxy Composite, Advances in Material Science and Engineering (2014). https://doi.org/10.1155/2014/538651\u003c/li\u003e\n\u003cli\u003eAdebisi A. A. and Maleque M. A. and Shah Q. H. (2011) Surface temperature distribution in a composite brake rotor. International Journal of Mechanical and Materials Engineering, 6 (3): 356-361. \u003c/li\u003e\n\u003cli\u003eAderiye J. (2014) Kaolin Mineral material for automotive ceramic brake pad manufacturing industry. International Journal of Technology Enhanancements and Emerging Engineering Research, Vol 2, Issue 3 ISSN 2347 \u0026ndash; 4289.\u003c/li\u003e\n\u003cli\u003eEkwedigwe, C., Nwambu, C., Nnuka, E., Effects of rice straw fibre and walnut shell ash particulates on the mechanical behavior of epoxy composite. Unizik Journal of Engineering and Applied Sciences 1 (1), 69-77.\u003c/li\u003e\n\u003cli\u003eYawas D. S., Aku S. Y. and Amaren S. G. (2013) Morphology and properties of periwinkle shell asbestos-free brake pad. Journal of King Saud University- Engineering Sciences.\u003c/li\u003e\n\u003cli\u003eEkwedigwe, C., Nnakwo, K., Nwambu, C., Viscoelastic properties of alkaline treated walnut shell/rice straw fiber/epoxy biocomposite. Journal of Civil Engineering and Environmental Science, 9 (1), 009-013. \u003c/li\u003e\n\u003cli\u003eMohamed Khazal Hussain, et al. - Fabrication of epoxy composite material reinforced with bamboo fibers, Journal of Applied Engineering Science Vol. 19, No. 1, 2021.\u003c/li\u003e\n\u003cli\u003eKannan, R., Ahmad, M. (2013). A review on mechanical properties of bamboo fiber reinforced polymer composite. Australian Journal of Basic and Applied Sciences, vol. 7, no. 8, pp. 247\u0026ndash;253. \u003c/li\u003e\n\u003cli\u003eCN Nwambu, GI Chibueze, EN Nwankwo, CM Ekwedigwe, (2023) Taguchi analysis of the tensile behaviour of unaged and hygrothermally aged asymmetric helicoidally stacked CFRP composites, Journal of Civil Engineering and Environmental Sciences 9 (2), 068-072.\u003c/li\u003e\n\u003cli\u003eC Nwambu, I Chibueze, K Iyebeye, C Ekwedigwe, (2023) Optimization of viscoelastic behaviors of bioinspired asymmetric helicoidal CFRP composites using Taguchi Method, Archive of Biomedical Science and Engineering 9 (1), 010-014.\u003c/li\u003e\n\u003cli\u003eW. U. Eze , M. K. Yakubu, M. A. Buba, A. Kuzmin, I. B. Santos-Ndukwe, M. I. Ugbaja 1 and A. H. Bayero (2022) Effect of Nano-Structured Bambara Nut Shell (Vigna Subterranea (L.) Verdc) As Filler on the Physical, Mechanical and Morphological Properties of Epoxy Matrix. Journal of Materials and Environmental Science, Vol. 13, Issue 10, PP 1155-1170.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Nnamdi Azikiwe 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":"Bambara nut shells, potato starch cellulose, hybrid composites, tensile strength, bio-agricultural waste","lastPublishedDoi":"10.21203/rs.3.rs-5689417/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5689417/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe increasing demand for sustainable materials has driven research into bio-agricultural waste as a reinforcement for hybrid composites. This study investigates the mechanical and morphological properties of hybrid epoxy composites reinforced with Bambara nutshell and potato starch particles. Composite samples were produced with varying reinforcement loadings (5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, and 30 wt%) and tested according to ASTM standards. Results show that tensile and flexural strengths increased significantly with reinforcement up to 25 wt%, achieving maximum values of 62.38 MPa and 84.21 MPa, respectively, due to optimal filler-matrix interaction. Beyond 25 wt%, strength properties declined because of poor wettability and filler agglomeration. Impact strength peaked at 5 wt% reinforcement with a value of 0.372 J/mm, but decreased at higher loadings due to increased brittleness. Microstructural analysis revealed that the improved performance at 25 wt% was attributed to better dispersion, fewer voids, and strong filler-matrix adhesion. These findings highlight the potential of utilizing agricultural waste to produce eco-friendly hybrid composites, contributing to sustainable materials development, reducing reliance on synthetic alternatives, and offering significant advantages for industrial and residential applications where lightweight materials with superior impact and tensile properties are required.\u003c/p\u003e","manuscriptTitle":"Mechanical and Microstructural Optimization of Hybrid Epoxy Composites with Renewable Bambara Nut Shells and Potato Starch Reinforcement","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-30 09:40:21","doi":"10.21203/rs.3.rs-5689417/v1","editorialEvents":[{"type":"communityComments","content":1}],"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":"bf39fe9a-c572-4943-be4f-97692436f70b","owner":[],"postedDate":"December 30th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":41930493,"name":"Renewable Resources"}],"tags":[],"updatedAt":"2024-12-30T09:40:21+00:00","versionOfRecord":[],"versionCreatedAt":"2024-12-30 09:40:21","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5689417","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5689417","identity":"rs-5689417","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}