End-of-life options of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)-based blends

End-of-life options of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)-based blends | 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 End-of-life options of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)-based blends Asanda Mtibe, N.E. Nomadolo, T. C. Mokhena, L. Hlekelele, M. J. John This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7533610/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 09 Jan, 2026 Read the published version in Polymer Bulletin → Version 1 posted 9 You are reading this latest preprint version Abstract In this study, the end-of-life options of PHBH and PBAT blends were investigated. The blends were fabricated and optimized in a twin-screw extruder and injection moulding techniques. PBAT with high ductility was added to a brittle polymer, PHBH xx31n , to improve the ductility and toughness of the brittle polymer. The processed blends were tested for thermal and mechanical properties. It was discovered that the blend comprising PHBH and PBAT in an 80/20 ratio exhibits good tensile strength, tensile modulus, and elongation at break when compared to other blends. The blend exhibited lower thermal stability, with a degradation temperature that was lower when compared to neat PHBH and PBAT. The blends were also exposed to QUV radiation for degradation. The thermal stability of the blend was slightly improved with the increased exposure time. Visual analysis revealed photo-oxidative yellowing in the blends, and tensile properties were decreased with increased exposure time. FTIR spectroscopy displayed a carbonyl group at 1720 cm − 1 , confirming the degradation of the material. The results obtained by monitoring the integrity of the materials reveal that the material started biodegrading after 12 weeks and reached 90% in 180 days. The results demonstrate that the processed blends are compostable according to ASTM D5338, making composting a viable end-of-life disposal method for the blends. Polybutylene adipate terephthalate (PBAT) Poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) Properties Biodegradability Aging Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction The petroleum-based polymers market has grown at a rapid pace over the past few decades due to their applications in the automotive, food packaging, agriculture, textile, and biomedical industries [ 1 , 2 ]. It was reported that the global production capacity of petroleum-based plastics was estimated at around 400 million metric tons in 2022 and is anticipated to triple to 1.231 billion metric tons by 2060 [ 3 ]. The petroleum-based plastics were the material of choice due to their unique properties, such as water resistance, lightweight, excellent mechanical properties, moldability into various shapes, and long-lasting durability, making them a suitable candidate for outdoor furniture [ 4 , 5 ]. These polymers, particularly those used for single-use and short-term items, follow a linear economy (extraction of resources, conversion into products, use, and subsequent discard as waste), resulting in the generation of significant plastic waste. Most plastic products are not recyclable, and therefore, they end up in landfills after use, contributing to plastic pollution. Therefore, they fragment into microplastics, which end up in aquatic environments and pose a threat to aquatic animals [ 6 ]. Plastic waste is accumulating in the environment because proper waste management systems are not well established in most countries, especially in developing countries. As a result, there has been growing environmental awareness from the government, scientific communities, and regulatory bodies to promote the development of environmentally friendly and sustainable products to replace petroleum-based polymers. In this regard, biodegradable polymers have been identified as a viable alternative to non-biodegradable petroleum-based plastics in addressing plastic waste issues [ 2 ]. Biodegradable polymers reduce plastic waste in the environment due to their biodegradable nature. The biodegradation of biodegradable polymers is achieved by subjecting them to microbes as a carbon source, thereby mineralizing them into carbon dioxide, water, and biomass [ 2 ]. This phenomenon is referred to as biotic degradation. It is worth noting that the degradation of plastics depends on the environment, properties of the polymer, and the presence of microorganisms. Biodegradable polymers also undergo degradation when exposed to natural conditions such as heat, moisture, and sunlight [ 5 ]. This process is called abiotic degradation. The exposure of polymers to these conditions leads to polymer chain scission, thereby forming residual material that can subsequently be biodegraded into water, carbon dioxide, and biomass when subjected to microbial action. Biodegradable polymers such as polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT), and polyhydroxyalkanoates (PHAs) have been manufactured and commercialized in the last decades. The rate of biodegradation of these polymers in different environments has been tested using the standard methods. For instance, the biodegradation in industrial composting conditions is evaluated using ASTM D5338 [ 7 ], which indicates that approximately 90% or more of the material should biodegrade by 180 days into water, carbon dioxide, and biomass. Studies have shown that biodegradable polymers biodegrade in industrial composting within 180 days [ 2 , 8 ]. Although these polymers have been extensively investigated, there are very few studies reported on blending Poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) (PHBH) and polybutylene adipate terephthalate (PBAT). In this work, the blending of brittle PHBH with a highly ductile and tough PBAT improves the performance of the ensuing blend. Based on our best knowledge, there is very little information published on blending PHBH and PBAT. In addition, very few studies reported in the literature investigated both abiotic and biotic degradation of PHBH and PBAT. This study aimed to fabricate PHBH and PBAT blends and explore their mechanical and thermal properties. Furthermore, the end-of-life options (biodegradation) of the blends were investigated using standard methods. 2. Materials and methods 2.1. Materials Polybutylene adipate terephthalate (PBAT) Ecoflex C1200 grade was purchased from BASF, South Africa, and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) XX31n grade was purchased from Kaneka, Japan. 2.2.1. Compost An aerated 3-month organic-rich compost used for biodegradation studies was obtained from Garden-Master Compost, Pretoria, South Africa. The compost was prepared by passing it through a sieve with a mesh of < 0.8 cm to achieve uniform particle sizes. The physical and chemical properties of compost are tabulated in Table 1 . The compost properties presented meet the standard requirements according to the ASTM D5338[ 7 ] standard. Table 1 Physical-chemical properties of compost used in this study. Analysis Compost (%) Total dry solids (%) 53.6 Volatile solids (%) 54.8 pH of the compost solution 7.4 Total organic carbon content (%) 15.2 Total Nitrogen (%) 0.5 Carbon/Nitrogen ratio 30.3 Respiration rate (mg CO 2 /g compost)​ 62.1 2.2. Methods 2.2.1. Preparation of blends Before processing, PHBH and PBAT were dried in an oven at 80 ᵒC for 8 hrs. Different ratios, i.e., PHBH/PBAT (90/10, 80/20, 70/30, 60/40, and 50/50) were optimized in a melt extruded in a co-rotating twin-screw extruder with L/D40:1, model: TE-30/600-11-40. The processing temperatures ranged from 120 to 155°C with a screw speed of 25 rpm and a feeder rate of 20 rpm. The extruded filament was pelletized, and the pellets were dried in an oven at 80 ᵒC for overnight. The pellets after drying were processed in an injection moulding instrument (ENGEL e-mac50, ENGEL AUSTRIA GmbH, Schwertberg, Austria) with a 500-kN press to produce dog-bone specimens for tensile testing. The heating zone temperatures were between 150 and 155 ᵒC. 2.2.2. Aging studies The dog-bone samples were aged by UV exposure according to ISO 4892-3[ 9 ] in a weathering chamber. QUV Exposure using fluorescent UVA lamps in the region at 340 nm for 120, 240, and 360 hours. The test cycle consists of two steps: exposure to the UV light and condensation. The samples were exposed to UV light at 0.79W/m 2 irradiance at 60°Cfor 8 hours, followed by condensation at 50°C for 4 hours. These steps were repeated until the experiments were completed. Samples were numbered before they were placed in the QUV chamber to facilitate changes in each specimen. To predict the degradation in the natural environment that corresponds to accelerated aging QUV chamber, the following considerations were made: The average solar radiation in South Africa is 220W/m 2 per day, equivalent to 19.008 MJ/m 2 /day [ 10 ]. According to Wolf et al. [ 11 ] and Souza et al [ 12 ] about 6.3% of total energy is ultraviolet A-type radiation (UVA). Therefore, a total of 1.197 MJ/m 2 /day is referred to as a UVA. The ultraviolet lamp used in this work has a specification for UVA irradiance of 0.79 W/m 2 , which is equivalent to 0.06826 MJ/m 2 for each day. It is worth mentioning that the experiments run in two cycles of 12 hours, 8 hours of radiation, and 4 hours of condensation in each cycle. Therefore, each day (24 hours), samples are exposed to radiation for 16 hours. Consequently, the UVA radiation in a day supplied by the equipment is 0.0455 MJ/m 2 . To predict the test time in real life, the expected solar radiation of 1.197 MJ/m 2 was divided by the daily radiation supplied by the equipment (0.0455 MJ/m 2 ) multiplied by the time of exposure (15 days). This equals 394.62 days (13.2 months). 2.2.3. Biodegradation studies 2.2.3.1. Industrial composting testing as per the ASTM D5338 standard​ Aerobic biodegradation testing of test samples (Fig. 1 ) was studied in three replicates under controlled composting conditions at 58–60℃ by measuring carbon dioxide evolution as per ASTM D5338 standard test methods [ 7 ]​. The method followed in this study is similar to the method reported by Nomadolo and co-workers [ 13 ]. The compost was mixed with ground perlite particles at a ratio of 1:1. The purpose of the ground perlite particles is to maintain humidity, aerobic conditions, and eliminate noise during the test. The extruded pellets were ground and added to the compost and ground perlite mixture in a ratio of 1:6 weight by weight. About 9 biometer-respirometric flasks were used. Three flasks for the test blank (compost), three for the positive control (cellulose reference), and the other three for the test sample. In this test, a solution of potassium hydroxide (KOH) 0.5 M was placed on top of the compost mixture in an oven, as shown in Fig. 1 . The oven was set at 58°C, and the solution was used to absorb the CO 2 released from the test samples to produce potassium carbonate (K 2 CO 3 ). K 2 CO 3 was precipitated by barium chloride (BaCl 2 ) to form barium carbonate (BaCO 3 ). The reaction is shown below. CO 2 + 2KOH → K 2 CO 3 + H 2 O (1) K 2 CO 3 + BaCl 2 → BaCO 3 + 2KCl (2) The amount of released CO 2 was determined by titrating the KOH solution containing CO 2 with hydrochloric acid (HCl) solution every 2–4 days. A fresh 0.5 M KOH solution was prepared after every sampling and placed in a test flask to absorb CO 2 until the test was completed. Also, the compost moisture content was maintained between 50–55% relative humidity throughout testing. The rate of biodegradation was determined by subtracting the amount of CO 2 released by the blank from the amount of CO 2 released by the sample. The resultant CO 2 was divided by theoretical CO 2 to obtain the rate of biodegradation. Theoretical CO 2 was calculated using Eq. 3. Where CO 2 (t) is the theoretical CO 2 , M t is the total dry weight of the sample, and C t is the carbon content of the sample. The rate of biodegradation for each test sample was calculated using Eq. 4. Where (CO 2 )s and (CO 2 )b are the amounts of CO 2 released in the sample and the blank, respectively, and CO 2 (t) is the theoretical CO 2 . $$\:Biodegradation\left(\%\right)=\frac{\left({CO}_{2}\right)s-\left({CO}_{2}\right)b}{\left({CO}_{2}\right)t}\times\:100\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(4\right)\:\:\:\:\:\:\:\:\:\:$$ 2.2.3.2. Disintegration Parallel to composting, for disintegration test observations, dog bone test specimens were incubated under the same conditions as composted samples, but KOH was not used to trap CO 2 . 2.3. Characterization 2.3.1. Tensile testing Injection moulded dog-bone test specimens were conditioned at a temperature of 24°C and a relative humidity of 55% for 48 hours before tensile testing. Samples were tested on an Instron universal tensile tester (model 5966, Norwood, MA, USA) in compliance with the standard ASTM D638 [ 14 ]. 2.3.2. Fourier transform infrared (FTIR) spectroscopy The chemical structure of the PHBH/PBAT blend before and after exposure to QUV was examined using an Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) 4000 spectrophotometer (PerkinElmer, USA). The samples were scanned in the wavelength range from 4000 to 650 cm − 1 with an average of 32 scans and a resolution of 4 cm − 1 . The carbonyl index was calculated from spectra by dividing the intensity of the C = O peak by the intensity of the C-H peak. 2.3.3. Thermogravimetric analysis (TGA) A thermogravimetric analyzer (Pyris– PerkinElmer 5500) was used to measure the degradation temperature of the sample. The samples were heated in temperatures ranging from 30 to 700 ºC at a rate of 20 ºC/min under a nitrogen atmosphere. 2.3.4. Differential Scanning Calorimetry (DSC) Samples were weighed and analyzed in a DSC (model 8500, PerkinElmer, Branford, CT, USA) at temperatures ranging from − 60 to 190 ⁰C under a constant nitrogen flow of 25 ml/min and heating rate of 10 ᵒC min − 1 . The sample underwent three cycles: heating, cooling, and reheating. The results presented were based on cooling and second heating. 3. Results and discussions 3.1. Tensile properties Tensile properties of the neat biopolymers and blends are shown in Table 2 . The results demonstrate that the neat PBAT is a ductile and tough biopolymer with an elongation at break of more than 1000% but a relatively low tensile strength of about 8.5 MPa and a lower tensile modulus of 63 MPa. On the other hand, neat PHBH displayed a brittle behavior with an elongation at break of about 11% but had a relatively high tensile strength of about 31 MPa and a tensile modulus of 848 MPa. To decrease the brittle behavior of PHBH, it was blended with PBAT, a ductile and tough biopolymer. The results revealed that the blending of PHBH with PBAT improved PHBH's flexibility. As anticipated, the increase in PBAT loading resulted in an increase in elongation at the break of PHBH. It is worth noting that the increase in elongation at break did not increase significantly. Conversely, the tensile strength and modulus decreased significantly when the loading of PBAT increased from 10 to 50 wt.%. Similar behavior was reported by PCL Ivorra-Martinez et al.[ 15 ] where PHBH was blended with poly(caprolactone), a tough polymer. It was also discussed in the study reported by Aversa et al.[ 16 ] that the increase in the loading of poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) from 10 to 30 wt.% led to a decrease in tensile strength and modulus, whereas elongation at break increased. The formulation comprising PHBH and PBAT in an 80/20 ratio exhibits good tensile strength (27 MPa), tensile modulus, and elongation at break. Due to the promising mechanical properties of this blend, it was selected for further abiotic and biotic degradation studies. The results presented in this paper confirm what was presented in other studies regarding the improvement of flexibility by blending a brittle polymer with a tough polymer [ 15 , 16 ]. Table 2 Tensile properties of neat biopolymers and blends at different loadings. Material Tensile strength (MPa) Tensile Modulus (MPa) Elongation at break% PHBH XX31n 30.95 ± 0.35 848.10 ± 35.10 10.77 ± 0.66 PBAT 8.54 ± 0.17 63.32 ± 1.41 1005.50 ± 22.62 PHBH XX31n /PBAT (90/10) 27.50 ± 0.45 671.38 ± 27.86 16.92 ± 1.48 PHBH XX31n /PBAT (80/20) 26.53 ± 0.94 603.48 ± 48.53 21.32 ± 1.40 PHBH XX31n /PBAT (70/30) 22.68 ± 0.41 529.85 ± 12.06 21.75 ± 2.20 PHBH XX31n /PBAT (60/40) 17.56 ± 0.45 376.28 ± 20.67 21.27 ± 2.80 PHB HXX31n /PBAT (50/50) 11.98 ± 0.60 210.66 ± 21.01 23.67 ± 4.68 The changes in tensile properties of the blends were monitored after exposure to UV radiation. Table 3 presents the tensile properties of the unexposed blend and the blend exposed in QUV at different times (120, 240, and 360 hrs). The results demonstrate that the exposure of the blend to UV radiation decreases the tensile strength and elongation at break when the exposure time increases. In contrast, the exposure of the blend to UV radiation displayed an increase in tensile modulus. This suggests that as the blends were exposed longer to UV radiation, they became stiff and brittle. This behavior could be attributed to surface photo-crosslinking of polymer chains during UV exposure, as reported by other researchers [ 17 ]. This can be related to the degradation of the material over time. Similar observations were made by Singh et al.[ 18 ] working with the degradation of poly(furfuryl) alcohol (PFA) and PFA blended with polylactic acid (PLA). Table 3 Tensile of blends before and after exposure to QUV at different times. Material Tensile strength (MPa) Tensile Modulus (MPa) Elongation at break% Blend 26.53 ± 0.94 603.48 ± 48.53 21.32 ± 1.40 Blend 120 hrs 24.67 ± 0.73 602.46 ± 16.55 12.87 ± 0.34 Blend 240 hrs 22.19 ± 0.33 695.33 ± 11.2 7.97 ± 0.23 Blend 360 hrs 21.86 ± 0.35 636.75 ± 12.89 8.52 ± 0.21 3.2. Visual inspection of material exposed in QUV The exposure of the material to UV radiation results in a change of appearance, chemical structure, and mechanical, physical, and thermal characteristics. The blends' appearance changes after exposure to UV weathering are depicted in Fig. 2 . As seen in Fig. 2 a, the dog-bone specimen is whitish before degradation. After exposure for 120 hrs, the color of the blend remains unchanged, suggesting that the degradation was not significant. However, the color of the blend began to change to yellowish after 240 hrs of exposure. After 360 hrs of exposure, the color was transformed into yellowish. It is worth mentioning that the blends became more brittle after 360 hrs of exposure to UV radiation. This confirms the degradation of the material after exposure to UV radiation. These results are in agreement with a similar study on the degradation of PLA, where the surface color changes from transparent to white with the QUV weathering exposure [ 19 ]. 3.3. FTIR analysis FTIR was used to provide structural information on blends exposed to UV radiation. The FTIR spectra of blends exposed to UV radiation at various times is depicted in Fig. 3 . As depicted in Fig. 3 , the absorption band at 3395 cm − 1 corresponds to the OH stretching vibrations, whereas an absorption band at 2924 cm − 1 and 2853 cm − 1 corresponds to CH stretching vibrations. The absorption band that represented the C = O stretching vibrations appeared at 1720 cm − 1 , while the absorption bands corresponding to C-O were observed at 1272 cm − 1 and 1044 cm − 1 . It was reported in the study published by Zhou and co-workers that when PHBH blended with PLA at a ratio of 80:20 the absorption band at 1270 cm − 1 was associated with the stretching vibration of the C-O in the carboxyl group whereas, the absorption band at 1058 cm − 1 corresponds to the stretching vibration of the C-O in the hydroxyl group [ 20 ]. The absorption band at 1642 cm − 1 represents the carboxyl group as reported by Wang et al [ 21 ]. It is worth mentioning that all the bands were present in all spectra, although intensity decreased after UV radiation, indicating that the exposure to UV radiation did not change the chemical structure. It was noticed that the decrease in intensities was more prominent on the C = O and C-O absorption bands (1720 cm − 1 , 1272 cm − 1 , and 1044 cm − 1 ). The weakening of these bands confirms that the photodegradation process occurred in blends. This process causes the cleavage of bonds, thereby resulting in chain scission. Other researchers reported similar observations [ 21 – 23 ]. It was observed in this study that the carbonyl band shown at the wavenumber of 1720 cm − 1 decreases as the degradation advances. The exposure of the resultant blend to UV irradiation resulted in material degradation. As stated in the methods and materials section, the carbonyl index was calculated from FTIR spectra. It was reported in a study by Liao and co-workers[ 24 ] that the degree of degradation of polymeric materials can be estimated by carbonyl group concentration, as carboxyl acids are produced during the oxidation process. Figure 4 represents the calculated carbonyl index of the resultant blend at 120 hrs, 240 hrs, and 360 hrs UV exposure. As anticipated, it was demonstrated in Fig. 4 that the exposure of the blend to UV irradiation led to an increase in the carbonyl index. In addition, the increase in exposure time further increased the carbonyl index of the blends. However, this increase indicates the degradation of the material, mainly due to photo-oxidation [ 25 ]. A similar trend of increasing carbonyl index of polylactic acid due to the degradation in weathering conditions was reported by Lizárraga-Laborín et al. [ 26 ]. The degradation of the resultant blends can be due to chain scission, which leads to the formation of short chains of polymers, as reported in other studies [ 13 ]. 3.4. Thermal properties 3.4.1. Thermogravimetric analysis (TGA) Thermogravimetric analysis profiles and derivative thermogravimetric (DTG) curves for the neat PHBH and PBAT, their blends, and the blends exposed to UV irradiation at different times are shown in Fig. 5 a and b. As seen in Figs. 5 a and b, neat PHBH and neat PBAT displayed a single-step degradation. It was observed that PBAT is thermally more stable with a degradation temperature of 405 ᵒC than PHBH with a degradation temperature of 286 ᵒC, as depicted in Table 4 . The resultant blend demonstrated that the degradation undergoes a two-step process. This phenomenon could be due to the incompatibility of these two neat polymers. It can be assumed that the first degradation peak (Fig. 5 b) at around 290 ᵒC represents PHBH and at around 400 ᵒC represents PBAT. Interestingly, the blend displayed lower thermal stability with a degradation temperature of 279 ᵒC in comparison to neat PHBH and PBAT. The blend showed an improvement in thermal stability after exposure to UV irradiation. It is worth noting that the increase in exposure time to UV irradiation did not influence the thermal stability of blends; as a result, the degradation temperatures were almost the same. Table 4 Degradation temperatures and char formation of neat biopolymer, blends, and blends exposed to QUV Material Degradation temperature (ᵒC) Char residue % PHBH XX31n 286 - 1.9 PBAT 405 - 1.7 Blend 279 398 2.8 Blend 120 hrs 295 402 1.7 Blend 240 hrs 293 402 2.1 Blend 360 hrs 296 402 1.7 3.4.2. Differential Scanning Calorimeter (DSC) Figure 6 demonstrates the DSC heating curves of the neat PHBH, PBAT, and the PHBH/PBAT blend before and after exposure to QUV at different times. The corresponding melting temperatures (T m ), melting enthalpy (ΔH m ), cold crystallization temperatures (T cc ), and crystallization enthalpy (ΔH cc ) are recorded in Table 5 . Neat PBAT displayed a broad individual peak at a lower temperature of around 124 ᵒC, whereas neat PHBH displayed two sharp melting peaks at higher temperatures of around 134 and 147 ᵒC. Both neat biopolymers displayed one cold crystallization peak (Figure not shown). The PHBH/PBAT blend displayed two melting peaks similar to neat PHBH. In addition, the blend displayed a single cold crystallization peak (Figure not shown). The value of the melting temperatures of the small peak, as shown in Fig. 6 of the unexposed PHBH/PBAT blend, was intermediate (129.7 ᵒC) between those of the neat biopolymers. However, there was a slight shift in the melting temperature of a sharp peak towards lower temperatures (144.6 ᵒC) after blending PBAT and PHBH. Similarly, the cold crystallization temperatures of the PHBH/PBAT blend were intermediate between neat PHBH and neat PBAT. It is worth mentioning that the values of cold crystallization temperatures significantly decrease after exposure of the blends to QUV. This could indicate that the blend was degrading over time. Similar observations were reported in the study investigated by Nomadolo and co-workers[ 13 ]; they reported the aerobic biodegradation of blends. Wang et al.[ 27 ] reported that the decrease in Tc of (PBAT)/polyhydroxyalkanoate (PHA) blend after exposure to QUV makes PBAT prone to photodegradation, which is caused by the acidic carboxyl groups of the PHA that would accelerate the hydrolytic degradation of PBAT. It was also noticed that the exposure of blends to QUV significantly decreased the crystallization enthalpy (ΔH cc ) of the blends. The melting behavior demonstrates that in the blend exposed to QUV, the peaks were similar to unexposed blends and neat PHBH, as depicted in Fig. 6 . It is worth noting that the melting temperatures slightly decreased after 120 hours of exposure and remained the same until 360 hours of exposure to QUV. A similar trend was observed for the melting enthalpy (ΔH m ). The sharpness of the peaks was not affected by the exposure of the blends to QUV. Table 5 Melting and crystallization behaviour of neat biopolymers, blends, and blends exposed to QUV at different times. Material Melting temperature (T m ) (ᵒC) Heat enthalpy (ΔH m ) (J/g) Cold crystallization temperature (T cc ) (ᵒC) Heat enthalpy (ΔH cc ) (J/g) PHBH XX31n 133.7 146.8 16.8 25.8 93.14 58.01 PBAT 123.9 - 17.3 - 74.46 22.26 Blend 129.7 144.6 9.7 28.0 84.88 53.51 Blend 120 hrs 126.6 144.1 8.4 30.6 63.92 48.53 Blend 240 hrs 126.5 144.8 6.8 30.1 61.41 44.65 Blend 360 hrs 126.6 144.3 6.4 31.3 67.47 43.38 3.5. Visual inspection of disintegration The visual inspection was performed on the recovered dog bone specimens during the test, where they were incubated under the same conditions as simulated industrial composting. Figure 7 demonstrates blends before and after the disintegration test. As shown in Fig. 7 , in 0 days, the blends appeared to be whitish and smooth without any damage. Just after 4 weeks, the specimens were deteriorating, and organic matter was deposited on the surface of the blends. This could be due to the attachment of microbes on the surface of the blends. After 8 weeks, the specimen was developing cracks, indicating that microbes were beginning to consume blends as their source of energy. It was also noticed that the materials were losing their properties, and they became brittle. Furthermore, organic matter remained strongly attached to the surface, and specimens became brownish. The specimens were completely disintegrated into pieces after 12 weeks, suggesting that the material was biodegrading in the compost. However, after 12 weeks until 200 days, the pieces were getting smaller to the point where it was difficult to recover. 3.6. Biodegradation in Industrial Composting The biodegradation of biopolymers is influenced by environmental conditions, such as temperature in the case of industrial composting, and the characteristics of the material. Figure 8 depicts the biodegradation of the PHBH/PBAT blend and cellulose processed under industrial composting. The biodegradation of these materials was measured by determining the carbon dioxide (CO 2 ) emission produced during microbial action on these materials during industrial composting. This process demonstrates whether the materials are biodegradable according to international standards, i.e., ASTM D5338, or meet the requirements. Cellulose was used as a positive reference according to the standard. The results demonstrate that both cellulose and the blends are biodegradable in industrial compost, indicating the evaluation of CO 2 . The difference in the biodegradation profiles was observed; the biodegradation of cellulose was higher than that of the blend. This could be due to the presence of low molecular weight monomers on cellulose, such as glucose, which makes it easier for assimilation by microbes than higher molecular weight molecules in the blend [ 28 ]. As depicted in Fig. 8 , cellulose started biodegrading instantly just after 4 days, reaching 80% after 48 days and 100% after 65 days. In the blend case, the blend started a lag phase after 15 days with a biodegradation degree of about 2.5%. This phase was followed by accelerated mineralization between 24 and 145 days, with the biodegradation rate ranging from 7–82%. This could be due to the cleavage of ester bonds caused by microbial action on the blend, which acts as a carbon source; they release extracellular enzymes that accelerate hydrolysis, which leads to rapid biodegradation [ 13 , 27 ]. In fact, microbes in compost secrete enzymes called esterases to depolymerize biopolymers into oligomers, dimers, and monomers, which are then ultimately mineralized into carbon dioxide, water, and humus [ 29 ]. According to Mtibe et al.[ 2 ] and Kumari et al.[ 29 ] biodegradation of biopolymers involves many steps which include i) the absorption of moisture by polymeric materials making them bioavailable for microbes, ii) the attachment of microbes onto the polymeric material surface to assimilate, iii) breaking down of polymer chains by microbial action, iv) Formation of low molecular weight molecules such as oligomers, dimers, and monomers, and v) bioassimilation of low molecular weight molecules into water, carbon dioxide and new biomass. It is worth mentioning that the degree of biodegradation reached about 90% in 180 days under controlled composting conditions, which complies with the standard method, ASTM D5338 [ 7 ]. 4. Conclusions The increased production and consumption of plastic resulted in the generation of a huge amount of plastic waste. The lack of proper management of plastic waste has encouraged the development of viable alternatives to plastic, such as biodegradable polymers. This study investigated the fabrication of biopolymer blends as a replacement for synthetic polymers. The performance of the prepared blends was investigated using a tensile tester, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The findings highlighted that the prepared blends exhibited good tensile and thermal properties, matching those of commercially available polymers. The abiotic degradation of polymer blends was investigated by exposing blends to QUV at different times. The degradation of the ensuing blends was confirmed by the formation of a carbonyl band, the yellowing of the material, and a decrease in mechanical and thermal properties after exposure to QUV. The increase in exposure time in QUV led to further degradation of the material. The study highlighted that the significant disintegration was visible after 12 weeks, and the blends fragmented into pieces before bioassimilation occurred. The rate of biodegradation of blends was investigated under controlled industrial composting conditions. The blend demonstrated biodegradation under industrial composting conditions, reaching 90% within 180 days. The results suggest that the blends are compostable; however, further research is required to test these materials in real environmental conditions, as many research institutes do not have composting facilities. Declarations Conflict of interest The authors would like to declare that there is no conflict of interest. Author Contribution Conceptualization, A.M., L.H., M.J.J., and T.C.M.; methodology, A.M., L.H., and N.E.M.; software, A.M., T.C.M. and L.H.; validation, A.M., L.H., N.E.N., T.C.M., and M.J.J. formal analysis, A.M., L.H., T.C.M, N.E.N., and M.J.J.; investigation, A.M., L.H., T.C.M., N.E.N., S.M., and M.J.J.; resources, A.M., M.J.J. and N.E.M., writing—original draft preparation, A.M., L.H., M.J.J., and T.C.M.; writing—review and editing, A.M., and M.J.J.; funding acquisition, A.M., M.J.J. and N.E.N. All authors have agreed to the published version of the manuscript. Acknowledgements All the authors have contributed to this paper. The authors would like to thank the Department of Science and Innovation (DSI) and the National Research Foundation (NRF) Thuthuka (TTK240415214232) for financial support. References Spaccini R, Todisco D, Drosos M, et al (2016) Decomposition of bio-degradable plastic polymer in a real on-farm composting process. Chem Biol Technol Agric 3: 1–12. https://doi.org/10.1186/s40538-016-0053-9 Mtibe A, Motloung MP, Bandyopadhyay J, Ray SS (2021) Synthetic Biopolymers and Their Composites: Advantages and Limitations—An Overview. Macromol Rapid Commun 42: 2100130. https://doi.org/10.1002/marc.202100130 https://illuminem.com/illuminemvoices/by-2060-global-production-and-use-of-plastics-forecasted-to-triple (26/08/2025) Ge S, Ouyang H, Ye H, et al (2023) High-performance and environmentally friendly acrylonitrile butadiene styrene/wood composite for versatile applications in furniture and construction. Adv Compos Hybrid Mater 6: 44. https://doi.org/10.1007/s42114-023-00628-1 Nzimande MC, Mtibe A, Tichapondwa S, John MJ (2024) A Review of Weathering Studies in Plastics and Biocomposites—Effects on Mechanical Properties and Emissions of Volatile Organic Compounds (VOCs). Polymers (Basel) 16: 1103. https://doi.org/10.3390/polym16081103 Andrady AL (2022) Weathering and fragmentation of plastic debris in the ocean environment. Mar Pollut Bull 180:113761. https://doi.org/10.1016/j.marpolbul.2022.113761 ASTM D5338-15 (2021) Test Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled Composting Conditions, Incorporating Thermophilic Temperatures Musiol M, Sikorska W, Adamus G, et al (2016) Forensic engineering of advanced polymeric materials. Part III - Biodegradation of thermoformed rigid PLA packaging under industrial composting conditions. Waste Management 52:69–76. https://doi.org/10.1016/j.wasman.2016.04.016 ISO 4892-3 (2024) Plastics — Methods of exposure to laboratory light sources —Fluorescent UV lamps https://www.dmre.gov.za/energy-resources/energy-sources/renewable-alternative-fuels/solar-power (26/08/2025) Wolf R, Tüzün B, Tüzün Y (2001) Sunscreens. Dermatol Ther 14:208–214. https://doi.org/10.1046/j.1529-8019.2001.01027.x Souza PMS, Morales AR, Sanchez EMS, Mei LHI (2018) Study of PBAT Photostabilization with Ultraviolet Absorber in Combination with Hindered Amine Light Stabilizer and Vitamin E, Aiming Mulching Film Application. J Polym Environ 26:3422–3436. https://doi.org/10.1007/s10924-018-1229-0 Nomadolo N, Dada OE, Swanepoel A, et al (2022) A Comparative Study on the Aerobic Biodegradation of the Biopolymer Blends of Poly(butylene succinate), Poly(butylene adipate terephthalate) and Poly(lactic acid). Polymers (Basel) 14: 1894. https://doi.org/10.3390/polym14091894 ASTM D638 (2014) Test Method for Tensile Properties of Plastics Ivorra-Martinez J, Verdu I, Fenollar O, et al (2020) Manufacturing and properties of binary blend from bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly(caprolactone) with improved toughness. Polymers (Basel) 12: 1118. https://doi.org/10.3390/POLYM12051118 Aversa C, Barletta M, Koca N (2023) Processing PLA/P(3HB)(4HB) blends for the manufacture of highly transparent, gas barrier and fully bio-based films for compostable packaging applications. J Appl Polym Sci 140: e53669. https://doi.org/10.1002/app.53669 Quispe MM, López O V., Villar MA (2019) Oxidative degradation of thermoplastic starch induced by UV radiation. J Renew Mater 7:383–391. https://doi.org/10.32604/jrm.2019.04276 Singh P, Kumar KD, Kumar R (2022) Degradation of Polyfurfuryl Alcohol-Based Biopolymer by Soil-Burial and Photo-Degradation Methods. J Polym Environ 30:1920–1931. https://doi.org/10.1007/s10924-021-02330-z Yatigala NS, Bajwa DS, Bajwa SG (2018) Compatibilization improves physico-mechanical properties of biodegradable biobased polymer composites. Compos Part A Appl Sci Manuf 107:315–325. https://doi.org/10.1016/j.compositesa.2018.01.011 Zhou Y xin, Huang Z gang, Diao X qian, et al (2015) Characterization of the effect of REC on the compatibility of PHBH and PLA. Polym Test 42:17–25. https://doi.org/10.1016/j.polymertesting.2014.12.014 Wang JH, Tian Y, Zhou B (2022) Degradation and Stabilization of Poly(Butylene Adipate-co-Terephthalate)/Polyhydroxyalkanoate Biodegradable Mulch Films Under Different Aging Tests. J Polym Environ 30:1366–1379. https://doi.org/10.1007/s10924-021-02279-z Zhou Y xin, Huang Z gang, Diao X qian, et al (2015) Characterization of the effect of REC on the compatibility of PHBH and PLA. Polym Test 42:17–25. https://doi.org/10.1016/j.polymertesting.2014.12.014 Pinto J, Dias M, Amaral J, et al (2022) Influence of UV degradation of bioplastics on the amplification of mercury bioavailability in aquatic environments. Mar Pollut Bull 180: 113806. https://doi.org/10.1016/j.marpolbul.2022.113806 Liao J, Brosse N, Pizzi A, et al (2019) Polypropylene blend with polyphenols through dynamic vulcanization: Mechanical, rheological, crystalline, thermal, and UV protective property. Polymers (Basel) 11: 1108. https://doi.org/10.3390/polym11071108 Ramos-Hernández T, Robledo-Ortíz JR, González-López ME, et al (2023) Mechanical recycling of PLA: Effect of weathering, extrusion cycles, and chain extender. J Appl Polym Sci 140: e53759. https://doi.org/10.1002/app.53759 Lizárraga-Laborín LL, Quiroz-Castillo JM, Encinas-Encinas JC, et al (2018) Accelerated weathering study of extruded polyethylene/poly (lactic acid)/chitosan films. Polym Degrad Stab 155:43–51. https://doi.org/10.1016/j.polymdegradstab.2018.06.007 Wang JH, Tian Y, Zhou B (2022) Degradation and Stabilization of Poly(Butylene Adipate-co-Terephthalate)/Polyhydroxyalkanoate Biodegradable Mulch Films Under Different Aging Tests. J Polym Environ 30:1366–1379. https://doi.org/10.1007/s10924-021-02279-z del Rosario Salazar-Sánchez M, Campo-Erazo SD, Villada-Castillo HS, Solanilla-Duque JF (2019) Structural changes of cassava starch and polylactic acid films submitted to biodegradation process. Int J Biol Macromol 129:442–447. https://doi.org/10.1016/j.ijbiomac.2019.01.187 Venu Gopala Kumari S, Pakshirajan K, Pugazhenthi G (2024) Key insights into mechanism and kinetics of biodegradation of poly (3-hydroxybutyrate)-based nanocomposite films in natural soil and river water environments. Bioresour Technol 409: 131238. https://doi.org/10.1016/j.biortech.2024.131238 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 09 Jan, 2026 Read the published version in Polymer Bulletin → Version 1 posted Editorial decision: Revision requested 15 Oct, 2025 Reviews received at journal 15 Oct, 2025 Reviews received at journal 15 Oct, 2025 Reviewers agreed at journal 15 Oct, 2025 Reviewers agreed at journal 13 Oct, 2025 Reviewers invited by journal 29 Sep, 2025 Editor assigned by journal 24 Sep, 2025 Submission checks completed at journal 11 Sep, 2025 First submitted to journal 04 Sep, 2025 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. 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1","display":"","copyAsset":false,"role":"figure","size":321474,"visible":true,"origin":"","legend":"\u003cp\u003eIndustrial composting set-up.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/6fe65a8669b2619cdf75b8e5.png"},{"id":93260925,"identity":"459b1607-72ca-477e-bccb-5c9816ba29a9","added_by":"auto","created_at":"2025-10-10 18:13:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":637242,"visible":true,"origin":"","legend":"\u003cp\u003ePhotographs of test specimens before and after exposure to QUV at different times.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/76ca293854f56823bf036533.png"},{"id":93260929,"identity":"33b335b6-2e76-41bc-9039-fabf24b2b2c6","added_by":"auto","created_at":"2025-10-10 18:13:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":17231,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra of blends before and after exposure to QUV at different times.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/fc2ce76cd4d8a9e02c2fd065.png"},{"id":93261082,"identity":"2f03c385-0261-4a15-a516-113c4bc00dff","added_by":"auto","created_at":"2025-10-10 18:21:05","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":13128,"visible":true,"origin":"","legend":"\u003cp\u003eCarbonyl index before and after exposure to QUV at different times.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/299e60bc08e50cb502225e37.png"},{"id":93260927,"identity":"9b0fc3c8-4cf2-434a-83ae-a5b80ca0db27","added_by":"auto","created_at":"2025-10-10 18:13:05","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":33454,"visible":true,"origin":"","legend":"\u003cp\u003eTGA profiles a) and DTG b) of neat biopolymers, blends, and blends exposed to QUV at different times.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/f6eec0b3f8d766bac20993b8.png"},{"id":93260193,"identity":"fc037d38-3033-4451-a75a-7687c165066a","added_by":"auto","created_at":"2025-10-10 17:57:05","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":17370,"visible":true,"origin":"","legend":"\u003cp\u003eDSC curves of neat biopolymers, blends, and blends exposed to QUV at different times.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/60ef74d0e401d27eec46cb0a.png"},{"id":93260199,"identity":"e2592d2d-80db-4955-b219-34f193ccf27d","added_by":"auto","created_at":"2025-10-10 17:57:05","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":677090,"visible":true,"origin":"","legend":"\u003cp\u003ePhotograph of test specimens after the composting process disintegration studies.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/ccc6bd9efc5a382b329b7227.png"},{"id":93260196,"identity":"071c65bc-a4a3-400f-bcf5-d42fd390997b","added_by":"auto","created_at":"2025-10-10 17:57:05","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":12448,"visible":true,"origin":"","legend":"\u003cp\u003eBiodegradation of blends in industrial composting conditions.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/49eb9f7b626359aba76666d7.png"},{"id":100070842,"identity":"34b43c92-0275-42f9-9f74-a72686a8e336","added_by":"auto","created_at":"2026-01-12 16:18:35","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3093458,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7533610/v1/b97a8358-4f38-4885-9335-332d11c87005.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"End-of-life options of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)-based blends","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe petroleum-based polymers market has grown at a rapid pace over the past few decades due to their applications in the automotive, food packaging, agriculture, textile, and biomedical industries [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. It was reported that the global production capacity of petroleum-based plastics was estimated at around 400\u0026nbsp;million metric tons in 2022 and is anticipated to triple to 1.231\u0026nbsp;billion metric tons by 2060 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The petroleum-based plastics were the material of choice due to their unique properties, such as water resistance, lightweight, excellent mechanical properties, moldability into various shapes, and long-lasting durability, making them a suitable candidate for outdoor furniture [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. These polymers, particularly those used for single-use and short-term items, follow a linear economy (extraction of resources, conversion into products, use, and subsequent discard as waste), resulting in the generation of significant plastic waste. Most plastic products are not recyclable, and therefore, they end up in landfills after use, contributing to plastic pollution. Therefore, they fragment into microplastics, which end up in aquatic environments and pose a threat to aquatic animals [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePlastic waste is accumulating in the environment because proper waste management systems are not well established in most countries, especially in developing countries. As a result, there has been growing environmental awareness from the government, scientific communities, and regulatory bodies to promote the development of environmentally friendly and sustainable products to replace petroleum-based polymers. In this regard, biodegradable polymers have been identified as a viable alternative to non-biodegradable petroleum-based plastics in addressing plastic waste issues [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eBiodegradable polymers reduce plastic waste in the environment due to their biodegradable nature. The biodegradation of biodegradable polymers is achieved by subjecting them to microbes as a carbon source, thereby mineralizing them into carbon dioxide, water, and biomass [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. This phenomenon is referred to as biotic degradation. It is worth noting that the degradation of plastics depends on the environment, properties of the polymer, and the presence of microorganisms. Biodegradable polymers also undergo degradation when exposed to natural conditions such as heat, moisture, and sunlight [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This process is called abiotic degradation. The exposure of polymers to these conditions leads to polymer chain scission, thereby forming residual material that can subsequently be biodegraded into water, carbon dioxide, and biomass when subjected to microbial action.\u003c/p\u003e\u003cp\u003eBiodegradable polymers such as polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT), and polyhydroxyalkanoates (PHAs) have been manufactured and commercialized in the last decades. The rate of biodegradation of these polymers in different environments has been tested using the standard methods. For instance, the biodegradation in industrial composting conditions is evaluated using ASTM D5338 [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], which indicates that approximately 90% or more of the material should biodegrade by 180 days into water, carbon dioxide, and biomass. Studies have shown that biodegradable polymers biodegrade in industrial composting within 180 days [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Although these polymers have been extensively investigated, there are very few studies reported on blending Poly(3-hydroxybutyrate-\u003cem\u003eco\u003c/em\u003e-3-hydroxyhexanoate) (PHBH) and polybutylene adipate terephthalate (PBAT). In this work, the blending of brittle PHBH with a highly ductile and tough PBAT improves the performance of the ensuing blend. Based on our best knowledge, there is very little information published on blending PHBH and PBAT. In addition, very few studies reported in the literature investigated both abiotic and biotic degradation of PHBH and PBAT. This study aimed to fabricate PHBH and PBAT blends and explore their mechanical and thermal properties. Furthermore, the end-of-life options (biodegradation) of the blends were investigated using standard methods.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Materials\u003c/h2\u003e\u003cp\u003ePolybutylene adipate terephthalate (PBAT) Ecoflex C1200 grade was purchased from BASF, South Africa, and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)\u003csub\u003eXX31n\u003c/sub\u003e grade was purchased from Kaneka, Japan.\u003c/p\u003e\u003cdiv id=\"Sec4\" class=\"Section3\"\u003e\u003ch2\u003e2.2.1. Compost\u003c/h2\u003e\u003cp\u003eAn aerated 3-month organic-rich compost used for biodegradation studies was obtained from Garden-Master Compost, Pretoria, South Africa. The compost was prepared by passing it through a sieve with a mesh of \u0026lt;\u0026thinsp;0.8 cm to achieve uniform particle sizes. The physical and chemical properties of compost are tabulated in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The compost properties presented meet the standard requirements according to the ASTM D5338[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] standard.\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\u003ePhysical-chemical properties of compost used in this study.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAnalysis\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCompost (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal dry solids (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e53.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVolatile solids (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e54.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH of the compost solution\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e7.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal organic carbon content (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e15.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal Nitrogen (%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCarbon/Nitrogen ratio\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e30.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRespiration rate (mg CO\u003csub\u003e2\u003c/sub\u003e/g compost)​\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e62.1\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\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Methods\u003c/h2\u003e\u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\u003ch2\u003e2.2.1. Preparation of blends\u003c/h2\u003e\u003cp\u003eBefore processing, PHBH and PBAT were dried in an oven at 80 ᵒC for 8 hrs. Different ratios, i.e., PHBH/PBAT (90/10, 80/20, 70/30, 60/40, and 50/50) were optimized in a melt extruded in a co-rotating twin-screw extruder with L/D40:1, model: TE-30/600-11-40. The processing temperatures ranged from 120 to 155\u0026deg;C with a screw speed of 25 rpm and a feeder rate of 20 rpm. The extruded filament was pelletized, and the pellets were dried in an oven at 80 ᵒC for overnight. The pellets after drying were processed in an injection moulding instrument (ENGEL e-mac50, ENGEL AUSTRIA GmbH, Schwertberg, Austria) with a 500-kN press to produce dog-bone specimens for tensile testing. The heating zone temperatures were between 150 and 155 ᵒC.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\u003ch2\u003e2.2.2. Aging studies\u003c/h2\u003e\u003cp\u003eThe dog-bone samples were aged by UV exposure according to ISO 4892-3[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] in a weathering chamber. QUV Exposure using fluorescent UVA lamps in the region at 340 nm for 120, 240, and 360 hours. The test cycle consists of two steps: exposure to the UV light and condensation. The samples were exposed to UV light at 0.79W/m\u003csup\u003e2\u003c/sup\u003e irradiance at 60\u0026deg;Cfor 8 hours, followed by condensation at 50\u0026deg;C for 4 hours. These steps were repeated until the experiments were completed. Samples were numbered before they were placed in the QUV chamber to facilitate changes in each specimen.\u003c/p\u003e\u003cp\u003eTo predict the degradation in the natural environment that corresponds to accelerated aging QUV chamber, the following considerations were made:\u003c/p\u003e\u003cp\u003eThe average solar radiation in South Africa is 220W/m\u003csup\u003e2\u003c/sup\u003e per day, equivalent to 19.008 MJ/m\u003csup\u003e2\u003c/sup\u003e/day [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. According to Wolf et al. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] and Souza et al [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] about 6.3% of total energy is ultraviolet A-type radiation (UVA). Therefore, a total of 1.197 MJ/m\u003csup\u003e2\u003c/sup\u003e/day is referred to as a UVA.\u003c/p\u003e\u003cp\u003eThe ultraviolet lamp used in this work has a specification for UVA irradiance of 0.79 W/m\u003csup\u003e2\u003c/sup\u003e, which is equivalent to 0.06826 MJ/m\u003csup\u003e2\u003c/sup\u003e for each day. It is worth mentioning that the experiments run in two cycles of 12 hours, 8 hours of radiation, and 4 hours of condensation in each cycle. Therefore, each day (24 hours), samples are exposed to radiation for 16 hours. Consequently, the UVA radiation in a day supplied by the equipment is 0.0455 MJ/m\u003csup\u003e2\u003c/sup\u003e. To predict the test time in real life, the expected solar radiation of 1.197 MJ/m\u003csup\u003e2\u003c/sup\u003e was divided by the daily radiation supplied by the equipment (0.0455 MJ/m\u003csup\u003e2\u003c/sup\u003e) multiplied by the time of exposure (15 days). This equals 394.62 days (13.2 months).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\u003ch2\u003e2.2.3. Biodegradation studies\u003c/h2\u003e\u003cdiv id=\"Sec9\" class=\"Section4\"\u003e\u003ch2\u003e2.2.3.1. Industrial composting testing as per the ASTM D5338 standard​\u003c/h2\u003e\u003cp\u003eAerobic biodegradation testing of test samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) was studied in three replicates under controlled composting conditions at 58\u0026ndash;60℃ by measuring carbon dioxide evolution as per ASTM D5338 standard test methods [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]​. The method followed in this study is similar to the method reported by Nomadolo and co-workers [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe compost was mixed with ground perlite particles at a ratio of 1:1. The purpose of the ground perlite particles is to maintain humidity, aerobic conditions, and eliminate noise during the test. The extruded pellets were ground and added to the compost and ground perlite mixture in a ratio of 1:6 weight by weight. About 9 biometer-respirometric flasks were used. Three flasks for the test blank (compost), three for the positive control (cellulose reference), and the other three for the test sample.\u003c/p\u003e\u003cp\u003eIn this test, a solution of potassium hydroxide (KOH) 0.5 M was placed on top of the compost mixture in an oven, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The oven was set at 58\u0026deg;C, and the solution was used to absorb the CO\u003csub\u003e2\u003c/sub\u003e released from the test samples to produce potassium carbonate (K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e). K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e was precipitated by barium chloride (BaCl\u003csub\u003e2\u003c/sub\u003e) to form barium carbonate (BaCO\u003csub\u003e3\u003c/sub\u003e). The reaction is shown below.\u003c/p\u003e\u003cp\u003eCO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;2KOH \u0026rarr; K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO (1)\u003c/p\u003e\u003cp\u003eK\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;BaCl\u003csub\u003e2\u003c/sub\u003e \u0026rarr; BaCO\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;2KCl (2)\u003c/p\u003e\u003cp\u003eThe amount of released CO\u003csub\u003e2\u003c/sub\u003e was determined by titrating the KOH solution containing CO\u003csub\u003e2\u003c/sub\u003e with hydrochloric acid (HCl) solution every 2\u0026ndash;4 days. A fresh 0.5 M KOH solution was prepared after every sampling and placed in a test flask to absorb CO\u003csub\u003e2\u003c/sub\u003e until the test was completed. Also, the compost moisture content was maintained between 50\u0026ndash;55% relative humidity throughout testing. The rate of biodegradation was determined by subtracting the amount of CO\u003csub\u003e2\u003c/sub\u003e released by the blank from the amount of CO\u003csub\u003e2\u003c/sub\u003e released by the sample. The resultant CO\u003csub\u003e2\u003c/sub\u003e was divided by theoretical CO\u003csub\u003e2\u003c/sub\u003e to obtain the rate of biodegradation. Theoretical CO\u003csub\u003e2\u003c/sub\u003e was calculated using Eq.\u0026nbsp;3.\u003c/p\u003e\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/127393_c7e80a1c9bb65875/127393_custom_files/img1760118843.png\" style=\"width: 612px;\"\u003e\u003c/p\u003e\u003cp\u003eWhere CO\u003csub\u003e2\u003c/sub\u003e (t) is the theoretical CO\u003csub\u003e2\u003c/sub\u003e, M\u003csub\u003et\u003c/sub\u003e is the total dry weight of the sample, and C\u003csub\u003et\u003c/sub\u003e is the carbon content of the sample.\u003c/p\u003e\u003cp\u003eThe rate of biodegradation for each test sample was calculated using Eq.\u0026nbsp;4. Where (CO\u003csub\u003e2\u003c/sub\u003e)s and (CO\u003csub\u003e2\u003c/sub\u003e)b are the amounts of CO\u003csub\u003e2\u003c/sub\u003e released in the sample and the blank, respectively, and CO\u003csub\u003e2\u003c/sub\u003e (t) is the theoretical CO\u003csub\u003e2\u003c/sub\u003e.\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:Biodegradation\\left(\\%\\right)=\\frac{\\left({CO}_{2}\\right)s-\\left({CO}_{2}\\right)b}{\\left({CO}_{2}\\right)t}\\times\\:100\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(4\\right)\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section4\"\u003e\u003ch2\u003e2.2.3.2. Disintegration\u003c/h2\u003e\u003cp\u003eParallel to composting, for disintegration test observations, dog bone test specimens were incubated under the same conditions as composted samples, but KOH was not used to trap CO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Characterization\u003c/h2\u003e\u003cdiv id=\"Sec12\" class=\"Section3\"\u003e\u003ch2\u003e2.3.1. Tensile testing\u003c/h2\u003e\u003cp\u003eInjection moulded dog-bone test specimens were conditioned at a temperature of 24\u0026deg;C and a relative humidity of 55% for 48 hours before tensile testing. Samples were tested on an Instron universal tensile tester (model 5966, Norwood, MA, USA) in compliance with the standard ASTM D638 [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section3\"\u003e\u003ch2\u003e2.3.2. Fourier transform infrared (FTIR) spectroscopy\u003c/h2\u003e\u003cp\u003eThe chemical structure of the PHBH/PBAT blend before and after exposure to QUV was examined using an Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) 4000 spectrophotometer (PerkinElmer, USA). The samples were scanned in the wavelength range from 4000 to 650 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with an average of 32 scans and a resolution of 4 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The carbonyl index was calculated from spectra by dividing the intensity of the C\u0026thinsp;=\u0026thinsp;O peak by the intensity of the C-H peak.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section3\"\u003e\u003ch2\u003e2.3.3. Thermogravimetric analysis (TGA)\u003c/h2\u003e\u003cp\u003eA thermogravimetric analyzer (Pyris\u0026ndash; PerkinElmer 5500) was used to measure the degradation temperature of the sample. The samples were heated in temperatures ranging from 30 to 700 \u0026ordm;C at a rate of 20 \u0026ordm;C/min under a nitrogen atmosphere.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\u003ch2\u003e2.3.4. Differential Scanning Calorimetry (DSC)\u003c/h2\u003e\u003cp\u003eSamples were weighed and analyzed in a DSC (model 8500, PerkinElmer, Branford, CT, USA) at temperatures ranging from \u0026minus;\u0026thinsp;60 to 190 ⁰C under a constant nitrogen flow of 25 ml/min and heating rate of 10 ᵒC min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The sample underwent three cycles: heating, cooling, and reheating. The results presented were based on cooling and second heating.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"3. Results and discussions","content":"\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Tensile properties\u003c/h2\u003e\u003cp\u003eTensile properties of the neat biopolymers and blends are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The results demonstrate that the neat PBAT is a ductile and tough biopolymer with an elongation at break of more than 1000% but a relatively low tensile strength of about 8.5 MPa and a lower tensile modulus of 63 MPa. On the other hand, neat PHBH displayed a brittle behavior with an elongation at break of about 11% but had a relatively high tensile strength of about 31 MPa and a tensile modulus of 848 MPa. To decrease the brittle behavior of PHBH, it was blended with PBAT, a ductile and tough biopolymer. The results revealed that the blending of PHBH with PBAT improved PHBH's flexibility. As anticipated, the increase in PBAT loading resulted in an increase in elongation at the break of PHBH. It is worth noting that the increase in elongation at break did not increase significantly. Conversely, the tensile strength and modulus decreased significantly when the loading of PBAT increased from 10 to 50 wt.%. Similar behavior was reported by PCL Ivorra-Martinez et al.[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] where PHBH was blended with poly(caprolactone), a tough polymer. It was also discussed in the study reported by Aversa et al.[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] that the increase in the loading of poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) from 10 to 30 wt.% led to a decrease in tensile strength and modulus, whereas elongation at break increased. The formulation comprising PHBH and PBAT in an 80/20 ratio exhibits good tensile strength (27 MPa), tensile modulus, and elongation at break. Due to the promising mechanical properties of this blend, it was selected for further abiotic and biotic degradation studies. The results presented in this paper confirm what was presented in other studies regarding the improvement of flexibility by blending a brittle polymer with a tough polymer [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\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\u003eTensile properties of neat biopolymers and blends at different loadings.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaterial\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTensile strength (MPa)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTensile Modulus (MPa)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eElongation at break%\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePHBH\u003csub\u003eXX31n\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e30.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e848.10\u0026thinsp;\u0026plusmn;\u0026thinsp;35.10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e10.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.66\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePBAT\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e63.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e1005.50\u0026thinsp;\u0026plusmn;\u0026thinsp;22.62\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePHBH\u003csub\u003eXX31n\u003c/sub\u003e/PBAT (90/10)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e27.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e671.38\u0026thinsp;\u0026plusmn;\u0026thinsp;27.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e16.92\u0026thinsp;\u0026plusmn;\u0026thinsp;1.48\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePHBH\u003csub\u003eXX31n\u003c/sub\u003e/PBAT (80/20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e26.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e603.48\u0026thinsp;\u0026plusmn;\u0026thinsp;48.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e21.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1.40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePHBH\u003csub\u003eXX31n\u003c/sub\u003e/PBAT (70/30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e22.68\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e529.85\u0026thinsp;\u0026plusmn;\u0026thinsp;12.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e21.75\u0026thinsp;\u0026plusmn;\u0026thinsp;2.20\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePHBH\u003csub\u003eXX31n\u003c/sub\u003e/PBAT (60/40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e17.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e376.28\u0026thinsp;\u0026plusmn;\u0026thinsp;20.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e21.27\u0026thinsp;\u0026plusmn;\u0026thinsp;2.80\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePHB\u003csub\u003eHXX31n\u003c/sub\u003e/PBAT (50/50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e11.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e210.66\u0026thinsp;\u0026plusmn;\u0026thinsp;21.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e23.67\u0026thinsp;\u0026plusmn;\u0026thinsp;4.68\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe changes in tensile properties of the blends were monitored after exposure to UV radiation. Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e presents the tensile properties of the unexposed blend and the blend exposed in QUV at different times (120, 240, and 360 hrs). The results demonstrate that the exposure of the blend to UV radiation decreases the tensile strength and elongation at break when the exposure time increases. In contrast, the exposure of the blend to UV radiation displayed an increase in tensile modulus. This suggests that as the blends were exposed longer to UV radiation, they became stiff and brittle. This behavior could be attributed to surface photo-crosslinking of polymer chains during UV exposure, as reported by other researchers [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. This can be related to the degradation of the material over time. Similar observations were made by Singh et al.[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] working with the degradation of poly(furfuryl) alcohol (PFA) and PFA blended with polylactic acid (PLA).\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 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eTensile of blends before and after exposure to QUV at different times.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaterial\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTensile strength (MPa)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTensile Modulus (MPa)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eElongation at break%\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e26.53\u0026thinsp;\u0026plusmn;\u0026thinsp;0.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e603.48\u0026thinsp;\u0026plusmn;\u0026thinsp;48.53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e21.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1.40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 120 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e24.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e602.46\u0026thinsp;\u0026plusmn;\u0026thinsp;16.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e12.87\u0026thinsp;\u0026plusmn;\u0026thinsp;0.34\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 240 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e22.19\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e695.33\u0026thinsp;\u0026plusmn;\u0026thinsp;11.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e7.97\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 360 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e21.86\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e636.75\u0026thinsp;\u0026plusmn;\u0026thinsp;12.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e8.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\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\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\u003ch2\u003e3.2. Visual inspection of material exposed in QUV\u003c/h2\u003e\u003cp\u003eThe exposure of the material to UV radiation results in a change of appearance, chemical structure, and mechanical, physical, and thermal characteristics. The blends' appearance changes after exposure to UV weathering are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. As seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, the dog-bone specimen is whitish before degradation. After exposure for 120 hrs, the color of the blend remains unchanged, suggesting that the degradation was not significant. However, the color of the blend began to change to yellowish after 240 hrs of exposure. After 360 hrs of exposure, the color was transformed into yellowish. It is worth mentioning that the blends became more brittle after 360 hrs of exposure to UV radiation. This confirms the degradation of the material after exposure to UV radiation. These results are in agreement with a similar study on the degradation of PLA, where the surface color changes from transparent to white with the QUV weathering exposure [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003e3.3. FTIR analysis\u003c/h2\u003e\u003cp\u003eFTIR was used to provide structural information on blends exposed to UV radiation. The FTIR spectra of blends exposed to UV radiation at various times is depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. As depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the absorption band at 3395 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponds to the OH stretching vibrations, whereas an absorption band at 2924 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 2853 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponds to CH stretching vibrations. The absorption band that represented the C\u0026thinsp;=\u0026thinsp;O stretching vibrations appeared at 1720 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, while the absorption bands corresponding to C-O were observed at 1272 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1044 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. It was reported in the study published by Zhou and co-workers that when PHBH blended with PLA at a ratio of 80:20 the absorption band at 1270 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was associated with the stretching vibration of the C-O in the carboxyl group whereas, the absorption band at 1058 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponds to the stretching vibration of the C-O in the hydroxyl group [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The absorption band at 1642 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represents the carboxyl group as reported by Wang et al [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. It is worth mentioning that all the bands were present in all spectra, although intensity decreased after UV radiation, indicating that the exposure to UV radiation did not change the chemical structure. It was noticed that the decrease in intensities was more prominent on the C\u0026thinsp;=\u0026thinsp;O and C-O absorption bands (1720 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1272 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and 1044 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). The weakening of these bands confirms that the photodegradation process occurred in blends. This process causes the cleavage of bonds, thereby resulting in chain scission. Other researchers reported similar observations [\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIt was observed in this study that the carbonyl band shown at the wavenumber of 1720 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e decreases as the degradation advances. The exposure of the resultant blend to UV irradiation resulted in material degradation. As stated in the methods and materials section, the carbonyl index was calculated from FTIR spectra. It was reported in a study by Liao and co-workers[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] that the degree of degradation of polymeric materials can be estimated by carbonyl group concentration, as carboxyl acids are produced during the oxidation process. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e represents the calculated carbonyl index of the resultant blend at 120 hrs, 240 hrs, and 360 hrs UV exposure. As anticipated, it was demonstrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e that the exposure of the blend to UV irradiation led to an increase in the carbonyl index. In addition, the increase in exposure time further increased the carbonyl index of the blends. However, this increase indicates the degradation of the material, mainly due to photo-oxidation [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. A similar trend of increasing carbonyl index of polylactic acid due to the degradation in weathering conditions was reported by Liz\u0026aacute;rraga-Labor\u0026iacute;n et al. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The degradation of the resultant blends can be due to chain scission, which leads to the formation of short chains of polymers, as reported in other studies [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\u003ch2\u003e3.4. Thermal properties\u003c/h2\u003e\u003cdiv id=\"Sec21\" class=\"Section3\"\u003e\u003ch2\u003e3.4.1. \u003cb\u003eThermogravimetric analysis (TGA)\u003c/b\u003e\u003c/h2\u003e\u003cp\u003eThermogravimetric analysis profiles and derivative thermogravimetric (DTG) curves for the neat PHBH and PBAT, their blends, and the blends exposed to UV irradiation at different times are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea and b. As seen in Figs.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea and b, neat PHBH and neat PBAT displayed a single-step degradation. It was observed that PBAT is thermally more stable with a degradation temperature of 405 ᵒC than PHBH with a degradation temperature of 286 ᵒC, as depicted in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The resultant blend demonstrated that the degradation undergoes a two-step process. This phenomenon could be due to the incompatibility of these two neat polymers. It can be assumed that the first degradation peak (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb) at around 290 ᵒC represents PHBH and at around 400 ᵒC represents PBAT. Interestingly, the blend displayed lower thermal stability with a degradation temperature of 279 ᵒC in comparison to neat PHBH and PBAT. The blend showed an improvement in thermal stability after exposure to UV irradiation. It is worth noting that the increase in exposure time to UV irradiation did not influence the thermal stability of blends; as a result, the degradation temperatures were almost the same.\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\u003eDegradation temperatures and char formation of neat biopolymer, blends, and blends exposed to QUV\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\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=\"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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaterial\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eDegradation temperature (ᵒC)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eChar residue %\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePHBH\u003csub\u003eXX31n\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e286\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePBAT\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e405\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e279\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e398\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 120 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e295\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e402\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 240 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e293\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e402\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e2.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 360 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e296\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e402\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1.7\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\u003c/div\u003e\u003cdiv id=\"Sec22\" class=\"Section3\"\u003e\u003ch2\u003e3.4.2. Differential Scanning Calorimeter (DSC)\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e demonstrates the DSC heating curves of the neat PHBH, PBAT, and the PHBH/PBAT blend before and after exposure to QUV at different times. The corresponding melting temperatures (T\u003csub\u003em\u003c/sub\u003e), melting enthalpy (ΔH\u003csub\u003em\u003c/sub\u003e), cold crystallization temperatures (T\u003csub\u003ecc\u003c/sub\u003e), and crystallization enthalpy (ΔH\u003csub\u003ecc\u003c/sub\u003e) are recorded in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Neat PBAT displayed a broad individual peak at a lower temperature of around 124 ᵒC, whereas neat PHBH displayed two sharp melting peaks at higher temperatures of around 134 and 147 ᵒC. Both neat biopolymers displayed one cold crystallization peak (Figure not shown). The PHBH/PBAT blend displayed two melting peaks similar to neat PHBH. In addition, the blend displayed a single cold crystallization peak (Figure not shown). The value of the melting temperatures of the small peak, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e of the unexposed PHBH/PBAT blend, was intermediate (129.7 ᵒC) between those of the neat biopolymers. However, there was a slight shift in the melting temperature of a sharp peak towards lower temperatures (144.6 ᵒC) after blending PBAT and PHBH. Similarly, the cold crystallization temperatures of the PHBH/PBAT blend were intermediate between neat PHBH and neat PBAT. It is worth mentioning that the values of cold crystallization temperatures significantly decrease after exposure of the blends to QUV. This could indicate that the blend was degrading over time. Similar observations were reported in the study investigated by Nomadolo and co-workers[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]; they reported the aerobic biodegradation of blends. Wang et al.[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] reported that the decrease in Tc of (PBAT)/polyhydroxyalkanoate (PHA) blend after exposure to QUV makes PBAT prone to photodegradation, which is caused by the acidic carboxyl groups of the PHA that would accelerate the hydrolytic degradation of PBAT. It was also noticed that the exposure of blends to QUV significantly decreased the crystallization enthalpy (ΔH\u003csub\u003ecc\u003c/sub\u003e) of the blends. The melting behavior demonstrates that in the blend exposed to QUV, the peaks were similar to unexposed blends and neat PHBH, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. It is worth noting that the melting temperatures slightly decreased after 120 hours of exposure and remained the same until 360 hours of exposure to QUV. A similar trend was observed for the melting enthalpy (ΔH\u003csub\u003em\u003c/sub\u003e). The sharpness of the peaks was not affected by the exposure of the blends to QUV.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMelting and crystallization behaviour of neat biopolymers, blends, and blends exposed to QUV at different times.\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=\"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=\"left\" 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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaterial\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eMelting temperature (T\u003csub\u003em\u003c/sub\u003e) (ᵒC)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eHeat enthalpy (ΔH\u003csub\u003em\u003c/sub\u003e) (J/g)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eCold crystallization temperature (T\u003csub\u003ecc\u003c/sub\u003e) (ᵒC)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eHeat enthalpy (ΔH\u003csub\u003ecc\u003c/sub\u003e) (J/g)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePHBH\u003csub\u003eXX31n\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e133.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e146.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e16.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e25.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e93.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e58.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePBAT\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e123.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e74.46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e22.26\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e129.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e144.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e9.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e28.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e84.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e53.51\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 120 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e126.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e144.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e8.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e30.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e63.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e48.53\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 240 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e126.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e144.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e6.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e30.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e61.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e44.65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlend 360 hrs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e126.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e144.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e6.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e31.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e67.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e43.38\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\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec23\" class=\"Section2\"\u003e\u003ch2\u003e3.5. Visual inspection of disintegration\u003c/h2\u003e\u003cp\u003eThe visual inspection was performed on the recovered dog bone specimens during the test, where they were incubated under the same conditions as simulated industrial composting. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e demonstrates blends before and after the disintegration test. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, in 0 days, the blends appeared to be whitish and smooth without any damage. Just after 4 weeks, the specimens were deteriorating, and organic matter was deposited on the surface of the blends. This could be due to the attachment of microbes on the surface of the blends. After 8 weeks, the specimen was developing cracks, indicating that microbes were beginning to consume blends as their source of energy. It was also noticed that the materials were losing their properties, and they became brittle. Furthermore, organic matter remained strongly attached to the surface, and specimens became brownish. The specimens were completely disintegrated into pieces after 12 weeks, suggesting that the material was biodegrading in the compost. However, after 12 weeks until 200 days, the pieces were getting smaller to the point where it was difficult to recover.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec24\" class=\"Section2\"\u003e\u003ch2\u003e3.6. Biodegradation in Industrial Composting\u003c/h2\u003e\u003cp\u003eThe biodegradation of biopolymers is influenced by environmental conditions, such as temperature in the case of industrial composting, and the characteristics of the material. Figure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e depicts the biodegradation of the PHBH/PBAT blend and cellulose processed under industrial composting. The biodegradation of these materials was measured by determining the carbon dioxide (CO\u003csub\u003e2\u003c/sub\u003e) emission produced during microbial action on these materials during industrial composting. This process demonstrates whether the materials are biodegradable according to international standards, i.e., ASTM D5338, or meet the requirements. Cellulose was used as a positive reference according to the standard. The results demonstrate that both cellulose and the blends are biodegradable in industrial compost, indicating the evaluation of CO\u003csub\u003e2\u003c/sub\u003e. The difference in the biodegradation profiles was observed; the biodegradation of cellulose was higher than that of the blend. This could be due to the presence of low molecular weight monomers on cellulose, such as glucose, which makes it easier for assimilation by microbes than higher molecular weight molecules in the blend [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. As depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, cellulose started biodegrading instantly just after 4 days, reaching 80% after 48 days and 100% after 65 days. In the blend case, the blend started a lag phase after 15 days with a biodegradation degree of about 2.5%. This phase was followed by accelerated mineralization between 24 and 145 days, with the biodegradation rate ranging from 7\u0026ndash;82%. This could be due to the cleavage of ester bonds caused by microbial action on the blend, which acts as a carbon source; they release extracellular enzymes that accelerate hydrolysis, which leads to rapid biodegradation [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. In fact, microbes in compost secrete enzymes called esterases to depolymerize biopolymers into oligomers, dimers, and monomers, which are then ultimately mineralized into carbon dioxide, water, and humus [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. According to Mtibe et al.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] and Kumari et al.[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] biodegradation of biopolymers involves many steps which include i) the absorption of moisture by polymeric materials making them bioavailable for microbes, ii) the attachment of microbes onto the polymeric material surface to assimilate, iii) breaking down of polymer chains by microbial action, iv) Formation of low molecular weight molecules such as oligomers, dimers, and monomers, and v) bioassimilation of low molecular weight molecules into water, carbon dioxide and new biomass. It is worth mentioning that the degree of biodegradation reached about 90% in 180 days under controlled composting conditions, which complies with the standard method, ASTM D5338 [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eThe increased production and consumption of plastic resulted in the generation of a huge amount of plastic waste. The lack of proper management of plastic waste has encouraged the development of viable alternatives to plastic, such as biodegradable polymers. This study investigated the fabrication of biopolymer blends as a replacement for synthetic polymers. The performance of the prepared blends was investigated using a tensile tester, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The findings highlighted that the prepared blends exhibited good tensile and thermal properties, matching those of commercially available polymers. The abiotic degradation of polymer blends was investigated by exposing blends to QUV at different times. The degradation of the ensuing blends was confirmed by the formation of a carbonyl band, the yellowing of the material, and a decrease in mechanical and thermal properties after exposure to QUV. The increase in exposure time in QUV led to further degradation of the material. The study highlighted that the significant disintegration was visible after 12 weeks, and the blends fragmented into pieces before bioassimilation occurred. The rate of biodegradation of blends was investigated under controlled industrial composting conditions. The blend demonstrated biodegradation under industrial composting conditions, reaching 90% within 180 days. The results suggest that the blends are compostable; however, further research is required to test these materials in real environmental conditions, as many research institutes do not have composting facilities.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflict of interest\u003c/h2\u003e\u003cp\u003eThe authors would like to declare that there is no conflict of interest.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceptualization, A.M., L.H., M.J.J., and T.C.M.; methodology, A.M., L.H., and N.E.M.; software, A.M., T.C.M. and L.H.; validation, A.M., L.H., N.E.N., T.C.M., and M.J.J. formal analysis, A.M., L.H., T.C.M, N.E.N., and M.J.J.; investigation, A.M., L.H., T.C.M., N.E.N., S.M., and M.J.J.; resources, A.M., M.J.J. and N.E.M., writing\u0026mdash;original draft preparation, A.M., L.H., M.J.J., and T.C.M.; writing\u0026mdash;review and editing, A.M., and M.J.J.; funding acquisition, A.M., M.J.J. and N.E.N. All authors have agreed to the published version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e\u003cp\u003eAll the authors have contributed to this paper. The authors would like to thank the Department of Science and Innovation (DSI) and the National Research Foundation (NRF) Thuthuka (TTK240415214232) for financial support.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eSpaccini R, Todisco D, Drosos M, et al (2016) Decomposition of bio-degradable plastic polymer in a real on-farm composting process. Chem Biol Technol Agric 3: 1\u0026ndash;12. https://doi.org/10.1186/s40538-016-0053-9\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eMtibe A, Motloung MP, Bandyopadhyay J, Ray SS (2021) Synthetic Biopolymers and Their Composites: Advantages and Limitations\u0026mdash;An Overview. Macromol Rapid Commun 42: 2100130. \u0026nbsp; https://doi.org/10.1002/marc.202100130\u0026nbsp;\u003c/li\u003e\n \u003cli\u003ehttps://illuminem.com/illuminemvoices/by-2060-global-production-and-use-of-plastics-forecasted-to-triple (26/08/2025)\u003c/li\u003e\n \u003cli\u003eGe S, Ouyang H, Ye H, et al (2023) High-performance and environmentally friendly acrylonitrile butadiene styrene/wood composite for versatile applications in furniture and construction. Adv Compos Hybrid Mater 6: 44. https://doi.org/10.1007/s42114-023-00628-1\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eNzimande MC, Mtibe A, Tichapondwa S, John MJ (2024) A Review of Weathering Studies in Plastics and Biocomposites\u0026mdash;Effects on Mechanical Properties and Emissions of Volatile Organic Compounds (VOCs). Polymers (Basel) 16: 1103. https://doi.org/10.3390/polym16081103\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eAndrady AL (2022) Weathering and fragmentation of plastic debris in the ocean environment. Mar Pollut Bull 180:113761. https://doi.org/10.1016/j.marpolbul.2022.113761\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eASTM D5338-15 (2021) Test Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled Composting Conditions, Incorporating Thermophilic Temperatures\u003c/li\u003e\n \u003cli\u003eMusiol M, Sikorska W, Adamus G, et al (2016) Forensic engineering of advanced polymeric materials. Part III - Biodegradation of thermoformed rigid PLA packaging under industrial composting conditions. Waste Management 52:69\u0026ndash;76. https://doi.org/10.1016/j.wasman.2016.04.016\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eISO 4892-3 (2024) Plastics \u0026mdash; Methods of exposure to laboratory light sources \u0026mdash;Fluorescent UV lamps\u003c/li\u003e\n \u003cli\u003ehttps://www.dmre.gov.za/energy-resources/energy-sources/renewable-alternative-fuels/solar-power (26/08/2025)\u003c/li\u003e\n \u003cli\u003eWolf R, T\u0026uuml;z\u0026uuml;n B, T\u0026uuml;z\u0026uuml;n Y (2001) Sunscreens. Dermatol Ther 14:208\u0026ndash;214. https://doi.org/10.1046/j.1529-8019.2001.01027.x\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSouza PMS, Morales AR, Sanchez EMS, Mei LHI (2018) Study of PBAT Photostabilization with Ultraviolet Absorber in Combination with Hindered Amine Light Stabilizer and Vitamin E, Aiming Mulching Film Application. J Polym Environ 26:3422\u0026ndash;3436. https://doi.org/10.1007/s10924-018-1229-0\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eNomadolo N, Dada OE, Swanepoel A, et al (2022) A Comparative Study on the Aerobic Biodegradation of the Biopolymer Blends of Poly(butylene succinate), Poly(butylene adipate terephthalate) and Poly(lactic acid). Polymers (Basel) 14: 1894. https://doi.org/10.3390/polym14091894\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eASTM D638 (2014) Test Method for Tensile Properties of Plastics\u003c/li\u003e\n \u003cli\u003eIvorra-Martinez J, Verdu I, Fenollar O, et al (2020) Manufacturing and properties of binary blend from bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly(caprolactone) with improved toughness. Polymers (Basel) 12: 1118. https://doi.org/10.3390/POLYM12051118\u003c/li\u003e\n \u003cli\u003eAversa C, Barletta M, Koca N (2023) Processing PLA/P(3HB)(4HB) blends for the manufacture of highly transparent, gas barrier and fully bio-based films for compostable packaging applications. J Appl Polym Sci 140: e53669. https://doi.org/10.1002/app.53669\u003c/li\u003e\n \u003cli\u003eQuispe MM, L\u0026oacute;pez O V., Villar MA (2019) Oxidative degradation of thermoplastic starch induced by UV radiation. J Renew Mater 7:383\u0026ndash;391. https://doi.org/10.32604/jrm.2019.04276\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSingh P, Kumar KD, Kumar R (2022) Degradation of Polyfurfuryl Alcohol-Based Biopolymer by Soil-Burial and Photo-Degradation Methods. J Polym Environ 30:1920\u0026ndash;1931. https://doi.org/10.1007/s10924-021-02330-z\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eYatigala NS, Bajwa DS, Bajwa SG (2018) Compatibilization improves physico-mechanical properties of biodegradable biobased polymer composites. Compos Part A Appl Sci Manuf 107:315\u0026ndash;325. https://doi.org/10.1016/j.compositesa.2018.01.011\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eZhou Y xin, Huang Z gang, Diao X qian, et al (2015) Characterization of the effect of REC on the compatibility of PHBH and PLA. Polym Test 42:17\u0026ndash;25. https://doi.org/10.1016/j.polymertesting.2014.12.014\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eWang JH, Tian Y, Zhou B (2022) Degradation and Stabilization of Poly(Butylene Adipate-co-Terephthalate)/Polyhydroxyalkanoate Biodegradable Mulch Films Under Different Aging Tests. J Polym Environ 30:1366\u0026ndash;1379. https://doi.org/10.1007/s10924-021-02279-z\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eZhou Y xin, Huang Z gang, Diao X qian, et al (2015) Characterization of the effect of REC on the compatibility of PHBH and PLA. Polym Test 42:17\u0026ndash;25. https://doi.org/10.1016/j.polymertesting.2014.12.014\u0026nbsp;\u003c/li\u003e\n \u003cli\u003ePinto J, Dias M, Amaral J, et al (2022) Influence of UV degradation of bioplastics on the amplification of mercury bioavailability in aquatic environments. Mar Pollut Bull 180: 113806. https://doi.org/10.1016/j.marpolbul.2022.113806\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eLiao J, Brosse N, Pizzi A, et al (2019) Polypropylene blend with polyphenols through dynamic vulcanization: Mechanical, rheological, crystalline, thermal, and UV protective property. Polymers (Basel) 11: 1108. https://doi.org/10.3390/polym11071108\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eRamos-Hern\u0026aacute;ndez T, Robledo-Ort\u0026iacute;z JR, Gonz\u0026aacute;lez-L\u0026oacute;pez ME, et al (2023) Mechanical recycling of PLA: Effect of weathering, extrusion cycles, and chain extender. J Appl Polym Sci 140: e53759. https://doi.org/10.1002/app.53759\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eLiz\u0026aacute;rraga-Labor\u0026iacute;n LL, Quiroz-Castillo JM, Encinas-Encinas JC, et al (2018) Accelerated weathering study of extruded polyethylene/poly (lactic acid)/chitosan films. Polym Degrad Stab 155:43\u0026ndash;51. https://doi.org/10.1016/j.polymdegradstab.2018.06.007\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eWang JH, Tian Y, Zhou B (2022) Degradation and Stabilization of Poly(Butylene Adipate-co-Terephthalate)/Polyhydroxyalkanoate Biodegradable Mulch Films Under Different Aging Tests. J Polym Environ 30:1366\u0026ndash;1379. https://doi.org/10.1007/s10924-021-02279-z\u003c/li\u003e\n \u003cli\u003edel Rosario Salazar-S\u0026aacute;nchez M, Campo-Erazo SD, Villada-Castillo HS, Solanilla-Duque JF (2019) Structural changes of cassava starch and polylactic acid films submitted to biodegradation process. Int J Biol Macromol 129:442\u0026ndash;447. https://doi.org/10.1016/j.ijbiomac.2019.01.187\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eVenu Gopala Kumari S, Pakshirajan K, Pugazhenthi G (2024) Key insights into mechanism and kinetics of biodegradation of poly (3-hydroxybutyrate)-based nanocomposite films in natural soil and river water environments. Bioresour Technol 409: 131238. https://doi.org/10.1016/j.biortech.2024.131238 \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"polymer-bulletin","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pobu","sideBox":"Learn more about [Polymer Bulletin](http://link.springer.com/journal/289)","snPcode":"289","submissionUrl":"https://submission.nature.com/new-submission/289/3","title":"Polymer Bulletin","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Polybutylene adipate terephthalate (PBAT), Poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), Properties, Biodegradability, Aging","lastPublishedDoi":"10.21203/rs.3.rs-7533610/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7533610/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this study, the end-of-life options of PHBH and PBAT blends were investigated. The blends were fabricated and optimized in a twin-screw extruder and injection moulding techniques. PBAT with high ductility was added to a brittle polymer, PHBH \u003csub\u003exx31n\u003c/sub\u003e, to improve the ductility and toughness of the brittle polymer. The processed blends were tested for thermal and mechanical properties. It was discovered that the blend comprising PHBH and PBAT in an 80/20 ratio exhibits good tensile strength, tensile modulus, and elongation at break when compared to other blends. The blend exhibited lower thermal stability, with a degradation temperature that was lower when compared to neat PHBH and PBAT. The blends were also exposed to QUV radiation for degradation. The thermal stability of the blend was slightly improved with the increased exposure time. Visual analysis revealed photo-oxidative yellowing in the blends, and tensile properties were decreased with increased exposure time. FTIR spectroscopy displayed a carbonyl group at 1720 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, confirming the degradation of the material. The results obtained by monitoring the integrity of the materials reveal that the material started biodegrading after 12 weeks and reached 90% in 180 days. The results demonstrate that the processed blends are compostable according to ASTM D5338, making composting a viable end-of-life disposal method for the blends.\u003c/p\u003e","manuscriptTitle":"End-of-life options of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)-based blends","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-10 17:57:00","doi":"10.21203/rs.3.rs-7533610/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-10-15T08:52:43+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-15T07:02:08+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-15T06:48:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"167470595174598605849252687555957988571","date":"2025-10-15T06:09:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"139849389968254120317100079925513277868","date":"2025-10-13T13:11:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-29T11:01:58+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-24T14:28:27+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-11T14:29:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"Polymer Bulletin","date":"2025-09-04T07:59:17+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"polymer-bulletin","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pobu","sideBox":"Learn more about [Polymer Bulletin](http://link.springer.com/journal/289)","snPcode":"289","submissionUrl":"https://submission.nature.com/new-submission/289/3","title":"Polymer Bulletin","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d5fa6607-a1fa-4328-b275-5010cdd8e03e","owner":[],"postedDate":"October 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-12T16:16:36+00:00","versionOfRecord":{"articleIdentity":"rs-7533610","link":"https://doi.org/10.1007/s00289-025-06216-1","journal":{"identity":"polymer-bulletin","isVorOnly":false,"title":"Polymer Bulletin"},"publishedOn":"2026-01-09 15:59:22","publishedOnDateReadable":"January 9th, 2026"},"versionCreatedAt":"2025-10-10 17:57:00","video":"","vorDoi":"10.1007/s00289-025-06216-1","vorDoiUrl":"https://doi.org/10.1007/s00289-025-06216-1","workflowStages":[]},"version":"v1","identity":"rs-7533610","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7533610","identity":"rs-7533610","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}