Thermoplastic Starch Research Articles

Injection-molded thermoplastic cassava starch modified with single and mixed polyol plasticizers

Increasing interest in biodegradable and cost-effective materials derived from renewable resources has led to the development of injection-moldable thermoplastic starch (TPS). Plasticizers constitute an indispensable additive for manufacturing TPS, influencing both its thermomechanical processability and performance. The aim of the current work is thus to study the effect of single and mixed polyol plasticizers on the performance of injection-molded TPS. This study was carried out by using three types of polyols – glycerol, xylitol, and sorbitol– as single and equal-weight binary mixed plasticizers to modify cassava starch via extrusion. The resulting TPS extrudates were converted to test specimens via injection molding. Melt flow index, moisture content, water contact angle, and tensile and dynamic mechanical thermal properties of the materials were examined. In addition, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis were also conducted. The results show that the higher-molecular-weight polyols (xylitol and sorbitol) exhibited lower plasticizing efficiency but formed denser hydrogen-bonding interactions with starch molecules than the smaller-molecular-weight one (glycerol). In both single and mixed plasticizer systems, increasing the molecular weight of the polyol plasticizer led to enhancements of the tensile strength (up to 27 MPa (200 % increment) and 26 MPa (115 % increment) for single and mixed plasticizer systems, respectively), Young's modulus (up to 386 MPa (240 % increment) and 458 MPa (185 % increment) for single and mixed plasticizer systems, respectively), decomposition temperature (2–3 °C), and glass transition temperature (30–50 °C) of TPS and a reduction in its moisture content (60–80 %) and surface stickiness, though disadvantages included poorer thermomechanical processability and higher melt viscosity and brittleness. In conclusion, using a co-plasticizer of glycerol and xylitol is appropriate for injection-molded TPS articles considering both processability and performance. The obtained TPS has potential applications in edible or single-use biodegradable rigid products, such as pet chew toys, chopsticks, cutlery, plant pots, etc.

Optimizing Thermoplastic Starch Film with Heteroscedastic Gaussian Processes in Bayesian Experimental Design Framework

The development of thermoplastic starch (TPS) films is crucial for fabricating sustainable and compostable plastics with desirable mechanical properties. However, traditional design of experiments (DOE) methods used in TPS development are often inefficient. They require extensive time and resources while frequently failing to identify optimal material formulations. As an alternative, adaptive experimental design methods based on Bayesian optimization (BO) principles have been recently proposed to streamline material development by iteratively refining experiments based on prior results. However, most implementations are not suited to manage the heteroscedastic noise inherently present in physical experiments. This work introduces a heteroscedastic Gaussian process (HGP) model within the BO framework to account for varying levels of uncertainty in the data, improve the accuracy of the predictions, and increase the overall experimental efficiency. The aim is to find the optimal TPS film composition that maximizes its elongation at break and tensile strength. To demonstrate the effectiveness of this approach, TPS films were prepared by mixing potato starch, distilled water, glycerol as a plasticizer, and acetic acid as a catalyst. After gelation, the mixture was degassed via centrifugation and molded into films, which were dried at room temperature. Tensile tests were conducted according to ASTM D638 standards. After five iterations and 30 experiments, the films containing 4.5 wt% plasticizer and 2.0 wt% starch exhibited the highest elongation at break (M = 96.7%, SD = 5.6%), while the films with 0.5 wt% plasticizer and 7.0 wt% starch demonstrated the highest tensile strength (M = 2.77 MPa, SD = 1.54 MPa). These results demonstrate the potential of the HGP model within a BO framework to improve material development efficiency and performance in TPS film and other potential material formulations.

Retrogradation Behavior of Cassava Starch Modified by Different Surface Properties Nano‐Silica under Combined Actions of Tensile and Ultrasound

AbstractThe combined actions of tensile and ultrasound on the melting enthalpy, retrogradation kinetics, spherical morphology, crystal structure, thermal stability, hydrophilicity, and molecular chain of thermoplastic cassava starch (TPS) containing different surface properties nano‐silica (SiO2) are investigated. The result indicates that the melting enthalpy of TPS/SiO2 composite and the retrogradation rate increases under combined actions of tensile and ultrasound, and the sample containing hydrophobic nano‐SiO2 is greater than that of hydrophilic nano‐SiO2. The spherulites of TPS/SiO2 composite become obvious, and the contact angle increases; however, the thermal degradation temperature decreases. Under combined actions of tensile and ultrasound, the aggregation of nano‐SiO2 particles in the matrix reduces and the dispersion become uniform. TPS/SiO2 composite presents A+V type crystal structure, and V‐type crystal increases after the combined actions of tensile and ultrasound. The storage modulus, loss modulus, and glass transition temperature of TPS/SiO2 composite increase, and the sample containing hydrophobic nano‐SiO2 is higher than that of sample containing hydrophilic nano‐SiO2.

It’s not waste, it’s a resource: Utilizing industrial waste fibers/mineral fillers to attain flame retardant biocomposites

Integrating natural fibers derived from local industrial waste streams into thermoplastic starch (TPS) proves to be a promising approach towards sustainable flame retardant biocomposites. Initially, three types of waste fibers from the agave, coconut, and leather industries were evaluated for their flame retardant properties in combination with aluminum trihydroxide (ATH), an environmental friendly flame retardant. Leather fiber (BLF) exhibited the best flame retardant performance and were further investigated along with ATH and varying amounts of bentonite nanoclay to enhance the residual protective layer. The combination of multiple components shows improvement in performance while reducing the total load of filler. The images of the fire residues revealed that a more enclosed surface correlates with a reduction in the peak of heat release rate. Whereas higher amounts of bentonite does not deliver further inprovements, only 1 phr nanoclay in the novel multicomponent system of TPS, ATH, BLF, and bentonite synergistically improved the UL-94 rating from HB to V1. The proposed system brings together the different approaches using a renewable biopolymer, natural waste fibres, and envirnmentally friendly flame retardancy and thus, is striking for its combination of outstanding sustainablity, instant feasability, and sufficient fire performance.

Optimization of Barrier Properties of PLA/PBAT Polymers in Biodegradable Materials

AbstractDespite its popularity as a bio‐based biodegradable material, polylactic acid (PLA) has a number of shortcomings. Nevertheless, the combination of poly(butylene adipate co‐terephthalate) (PBAT) and thermoplastic starch (TPS) to enhance the mechanical properties of PLA was achieved through the utilisation of PLA/PBAT/TPS ternary composites, which were created through the calendering method. These composites exhibit advantageous characteristics, including high ductility, enhanced toughness, and biodegradability. The results of the water vapour permeability test indicate that the proportion of the material composition exhibiting the lowest value of water vapour permeability is 2.0571 g/m²·24h. The results of the water vapour transmission test demonstrate that the material generated by the composition ratio has the lowest water vapour transmission, indicating that the composite material blending effect is superior. The majority of current research employs nanocellulose as a substrate in PLA, with a paucity of studies investigating its use in PLA/PBAT/TPS composites. These composites are modified due to the notable divergence of nanocellulose from the hydrophobicity of the composite and its susceptibility to decomposition at elevated temperatures. This study establishes a foundation for future research in this field.

Multidimensional study of starch co‐plasticized with glycerol and isosorbide in TPS/PLA blends: Morphological, mechanical, thermal, and structural properties

AbstractBiodegradable blends of polylactic acid (PLA) and thermoplastic starch (TPS) co‐plasticized with glycerol (G) and isosorbide (i) in different ratios were prepared by extrusion in a single screw extruder. The G/isosorbide ratio varied within the range 27.5/2.5 to 15/15. The resulting materials were obtained through blown film extrusion and characterized using a variety of techniques. The plasticizing effect was identified through SEM and FTIR observations. In the SEM images, it was evident that most of the native crystalline structures were destructured. Furthermore, SEM observations showed phase separation of TPS and PLA in all samples, with phase dispersion differences depending on the co‐plasticizer ratio. The FTIR spectra of all TPS/PLA films showed that isosorbide caused changes in the absorption bands that suggested a reduction in the crystallinity of the native starch, agreeing with the XRD results that indicated the formation of different crystalline structures (EH type). The XRD results revealed a change in the crystal structure of the TPS phase influenced by the amount of isosorbide. Isosorbide increased tensile strength and reduced elongation due to strong interactions between the plasticizer and the starch chains through hydrogen bonds, con‐firmed by FTIR analysis. In general, it was established that isosorbide and G co‐plasticization, with small amounts of isosorbide (up to a ratio of 25:5 G/isosorbide), can be employed as an effective plasticizer without significantly affecting the tensile mechanical properties.

Thermoplastic starch/poly(butylene adipate-co-terephthalate) blown film with maltol and ethyl maltol preserving cake quality: Morphology and antimicrobial function

Maltol (MT) and ethyl maltol (EM) are flavoring compounds that release vapors into headspace, exerting antimicrobial effects and extending food shelf-life. This study investigated biodegradable films for packaged bakery quality. Biodegradable films (40 % polybutylene adipate terephthalate and 60 % thermoplastic starch) were produced via extrusion for films with varying MT and EM contents (1, 3, and 5 %). Scanning electron microscopy revealed smoother and more homogeneous film cross-sections with MT/EM, indicating reduced surface wrinkling. Fourier-transform infrared spectroscopy analysis suggested modified OH and CH stretching due to hydrogen bonding between TPS and EM/MT. The XRD pattern showed sharp MT crystallization, modifying crystal polymorphs of starch and PBAT. EM and MT films exhibited against Staphylococcus aureus after 24 h. Moreover, EM/MT films effectively delayed fungal growth in butter cake, inhibiting mold growth in butter cake more than twofold. These findings suggest that volatile compounds like MT/EM have promising potential for incorporation into PBAT/TPS films, creating active bakery packaging.

Starch-calcium inclusion complexes: Optimizing transparency, anti-fogging, and fluorescence in thermoplastic starch

With the increasing demand for anti-fogging transparent material and environmental concern, developing sustainable intrinsically hydrophilic and anti-fogging thermoplastic material is important. In this work, thermoplastic starch (TPS) films with good anti-fogging and optical properties were prepared via coordinative interactions with calcium chloride (CaCl2), zinc chloride (ZnCl2) and magnesium chloride (MgCl2). Among them, TPS with the incorporation of CaCl2 exhibited excellent anti-fogging and high optical transparency. Notably, the haze of TPS-0.2Ca just increased from 2.5 % to 3.8 %, with transparency remaining robust at 80 %. FTIR, XPS and 2D-WAXD results demonstrated the formation of inclusion complexes between Ca2+ and hydroxyl groups, which could modulate the hydrophobicity and hydrophilicity of TPS. Moreover, DMA, POM, and AFM results revealed that the formation of starch-calcium inclusion complex was crucial for achieving uniform intensity distribution, reduced crystalline areas, minimized light scattering, and decreased surface roughness, thereby contributing to the high transparency and low haze of TPS-Ca. Furthermore, TPS-Ca samples exhibited inherent fluorescent properties under UV light, showing the potential as disposable and eco-friendly fluorescence materials. This work provides new insights into design of sustainable TPS-based materials that combine robust antifogging performance with advanced optical property.

Soil burial degradation of chemically compatibilized poly(butylene adipate-co-terephthalate)/thermoplastic starch/poly(ε-caprolactone)/cellulose biocomposites

Developing bio-blends and biocomposites has become a widespread strategy to combat plastic pollution in line with sustainability principles and decarbonization necessities. Although chemically modified ternary and quaternary biocomposites are developing rapidly because of their broader processing and performance windows than single matrix and binary counterparts, a few have been reported about their biodegradation. Herein, diisocyanates-based chemically modified ternary biocomposites based on poly(butylene adipate-co-terephthalate), thermoplastic starch (TPS), poly(ε-caprolactone) (PCL), and cellulose (Mater-Bi/PCL/cellulose) are prepared and undergone soil burial biodegradation providing a broader perspective on biodegradation of complicated systems. The mass gain of sunflower sprouts, weight retention, and the appearance of biocomposites are studied and discussed in the course of biodegradation. The unfilled Mater-Bi/PCL bio-blends presented moderate mass loss over 12 weeks, attributed to the presence of TPS in the Mater-Bi phase. The PCL addition hindered TPS decomposition and featured a noticeably lower degradation rate compared to previous reports. A significant increase in the b* parameter (position on the blue-yellow axis in the CIELAB color space), along with the yellowness and whiteness indices, was observed. Prior to soil burial, roughness differences were negligible. Still, they significantly increased over time due to the higher hydrophilicity of unfilled Mater-Bi/PCL and biocomposite containing unmodified filler.

Modifying Cassava Starch via Extrusion with Phosphate, Erythorbate and Nitrite: Phosphorylation, Hydrolysis and Plasticization.

Extrusion processing of plasticized cassava starch, a prominent industrial crop, with chemical additives offers a thermo-mechanical approach to modify starch structures through physical and chemical interactions. This research investigates the interaction and morphology of thermoplastic cassava starch (TPS) blended with tetrasodium pyrophosphate (Na4P2O7), sodium tripolyphosphate (Na5P3O10), sodium hexametaphosphate (Na6(PO3)6), sodium erythorbate (C6H7O6Na), and sodium nitrite (NaNO2) via twin-screw extrusion. The effects of these additives on the chemical structure, thermal profile, water absorption, and solubility of the TPS were examined. The high temperature and shearing forces within the extruder disrupted hydrogen bonding at α-(1-4) and α-(1-6) glycosidic linkages within anhydroglucose units. Na4P2O7, Na5P3O10 and Na6(PO3)6 induced starch phosphorylation, while 1H NMR and ATR-FTIR analyses revealed that C6H7O6Na and NaNO2 caused starch hydrolysis. These additives hindered starch recrystallization, resulting in higher amorphous fractions that subsequently influenced the thermal properties and stability of the extruded TPS. Furthermore, the type and content of the added modifier influenced the water absorption and solubility of the TPS due to varying levels of interaction. These modified starch materials exhibited enhanced antimicrobial properties against Escherichia coli and Staphylococcus aureus in polyester blends fabricated via extrusion, with nitrite demonstrating the most potent antimicrobial efficacy. These findings suggest that starch modification via either phosphorylation or acid hydrolysis impacts the thermal properties, morphology, and hydrophilicity of extruded cassava TPS.

Properties of poly(butylene adipate-co-terephthalate)/thermoplastic starch filled with treated and untreated sugarcane bagasse fiber

Sugarcane bagasse, comprising fibrous rind and spongy pith, is frequently employed as a reinforcing agent in both concrete and plastic composites. In thin plastic films, sugarcane bagasse is typically utilized as finely ground particles within the composite film. The integration of this agricultural byproduct into biodegradable plastic films could potentially lower production expenses and promote the film's biodegradability. This study presents the development of poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) (90/10) formulations incorporating varying loadings of sugarcane bagasse fibers. The impact of alkaline and silane surface treatments on tensile strength, thermal properties, and water barrier properties was investigated. Upon the inclusion of sugarcane bagasse (5%, 10%, 15%, and 20%), a decrease in tensile strength from 23.47 to 8.41 MPa and elongation at break from 1135% to 55.83% was observed. Conversely, the Young's modulus increased from 47.12 to 188.50 MPa following the addition of 20% sugarcane bagasse in the PBAT/TPS matrix. Modest enhancements in tensile properties, thermal characteristics, and water barrier properties were noted after treating the bagasse fibers with alkaline and silane. Scanning Electron Microscope (SEM) analysis revealed that silane-treated sugarcane bagasse exhibited increased surface roughness due to the removal of lignin and hemicellulose, facilitating better adhesion between the fibers and the PBAT/TPS matrix.

Structural and Thermal Characterization of Some Thermoplastic Starch Mixtures

Structural and Thermal Characterization of Some Thermoplastic Starch Mixtures

Potentials of synthetic biodegradable mulch for improved livelihoods on smallholder farmers: a systematic review

Plastic waste in agriculture, particularly from polyethylene mulch, poses significant environmental challenges. Synthetic biodegradable mulch has emerged as a sustainable alternative, derived from renewable resources such as thermoplastic starch, polylactic acid, polyhydroxyalkanoates, and copolyesters. This review explores the benefits of synthetic biodegradable mulch, its environmental impact, and the policy landscape to support its adoption. A review of existing literature was conducted, focusing on three aspects: (1) the performance of synthetic biodegradable mulch in crop production and pest control, (2) the environmental, socioeconomic, and climate resilience compared to polyethylene mulch, and (3) the institutional policies that promote synthetic biodegradable mulch adoption. The analysis considered comparative data on yield, pest management, and sustainability metrics. Synthetic biodegradable mulch performs similarly or better than polyethylene mulch in various agricultural practices. It enhances crop yield, quality, and weed suppression, acts as a physical barrier against pests and diseases, reduces chemical usage, and aids in water and nutrient management. Moreover, synthetic biodegradable mulch offers environmental benefits by reducing plastic waste, microplastic pollution, and greenhouse gas emissions, contributing to climate change mitigation. While synthetic biodegradable mulch provides numerous advantages, adoption faces challenges such as high initial costs, farmer preferences, and the regulatory framework. Effective institutional policies and increased consumer demand could drive wider adoption, offering potential for improved livelihoods among small farmers while promoting environmental sustainability.

Biodegradation of thermoplastic starch by a newly isolated active microbial community: Deciphering the biochemical mechanisms controlling bioprocess robustness

Defining sustainable end-of-life routes for bioplastics comprises a task of outmost importance, while biological recycling constitutes the most favorable option for several biopolymers, such as thermoplastic starch (TPS). To our knowledge, this is the first study to assess the biodegradation of TPS pellets and films in aqueous cultures employing an acclimated microbial community. Biological treatment of bioplastics displayed a two-phase pattern that included different biodegradation rates, where TPS removal in the first phase remained high and decelerated in the second phase reaching a plateau. Thus, TPS weight reduction of 14.8 % was observed using pellets following 10 d of incubation, while although films exhibited higher reduction (slightly over 30 % in 15 d), the biodegradation rate was significantly reduced thereafter. Several changes of starch related bands were detected (using FTIR) in the surface of both pellets and films during the bioprocess, indicating induction of a common biodegradation pathway. Distinct bacterial assemblages were formed during the TPS biodegradation process and statistically significant differences were detected in the abundance of several genera between the two degradation phases. Fungal communities were more stable (Fusarium and Neocosmospora were dominant at all times) and there was no effect of biofilm or degradation phase on fungal community composition. Overall, a more diverse community incorporating lower catalytic activity was gradually formed, as confirmed by the shift between k-stategist and r-stategist taxa monitored, while crystalline over amorphous regions were enhanced in the biopolymer during TPS biodegradation, responses consistent with the biodegradation rate reduction observed in the plateau stage. The study highlighted the biochemical mechanism limiting TPS biodegradation processes and the significant potential of the newly isolated community in the development of TPS waste treatment technologies.

Production of Thermoplastic Starch-Aloe Vera Gel Film Embedded with Polyethylene for Improved Tensile Strength and Water Absorption

The water absorption characteristics of thermoplastic starch (TPS) reveal its ability to interact with and absorb water, influencing its overall performance in various applications. The introduction of aloe vera (AV) gel into the TPS polymeric matrix film has proven beneficial in enhancing tensile strength but a notable deficiency is observed in lowering water absorption percentage. Therefore, this paper aims to reduce the water absorption of the TPS30AV polymer matrix film by utilizing polyethylene (PE) without reducing the tensile strength performance of the TPS30AV film. The TPS30AV film was produced using melt-blending and hot-press techniques. Six samples were presented consisting of a control film (TPS30AV) and TPS30AV film with different concentrations of PE resins (5%, 10%, 20%, 30%, and 40%). The film's performance was assessed by examining its mechanical properties, water absorption, and water solubility. The finding shows that TPS30AV with 40% PE has the highest improvement in water absorption percentage which reduces from 309.86% to 34.16% but a tremendous decrement in tensile strength performance. However, TPS30AV with 10% PE has the highest tensile strength, 9.65 MPa with a 20.99% improvement in water absorption reduction. The properties obtained for TPS30AV10PE were also good inYoung's modulus and water solubility percentage. It shows that the film formulated is comparable with previous studies, and improvement has been achieved. As a conclusion, adding PE improved the polymeric structure of TPS30AV and can be used as a biodegradable food-packaging film.

Functionalization of poly(butylene adipate‐co‐terephthalate) and its compatibilizing effect on PBAT/thermoplastic starch blends

AbstractPoly(butylene adipate‐co‐butylene terephthalate) (PBAT)/thermoplastic starch (TPS) blends were prepared by melt blending. However, the processability and practical application of PBAT/TPS blends are limited by their poor compatibility. To enhance the compatibility between PBAT and TPS, PBAT was functionalized by maleic anhydride (MA) to prepare PBAT‐MA, and then it was employed as a compatibilizer for PBAT/PBAT‐MA/TPS blends. The effects of PBAT‐MA on the tensile properties, rheological properties, morphology, and dynamic mechanics of PBAT/PBAT‐MA/TPS blends were studied in detail. Rheological results revealed that the interaction between PBAT‐MA and TPS enhanced the segment entanglement ability and improved the compatibility of the blends, which enhanced the tensile properties of the blends. Compared with the PBAT/PBAT‐MA/TPS (50/0/50) blend, the tensile strength of the PBAT/PBAT‐MA/TPS (40/10/50) blend increased from 9.2 to 15.8 MPa, and the elongation at break increased from 326.9% to 1017.6%. The dynamic mechanical results showed that the Tg of PBAT and TPS were close to each other after the addition of PBAT‐MA, which confirmed that the compatibility of the blend was improved. This study provides a feasible approach to preparing high‐performance and cost‐effective PBAT/PBAT‐MA/TPS blends while expanding the application prospects of PBAT in the packaging industry and agricultural film.

3D Printing and Biodegradable Polymers

Abstract 3D printing technology has a wide range of applications in many industries, including automotive, aerospace, biomedical, electronics and packaging, requiring different types of filaments to be used in producing 3D printed objects. The most commonly used materials are metals, ceramics, composites and plastics of which the latter are most available. Since it is necessary to reduce pollution caused by waste from conventional petroleum-based plastics, biodegradable polymers made from renewable resources or produced synthetically have gained in importance recently. Polylactic acid, poly(butylene succinate), thermoplastic starch, poly(butylene adipate co-terephthalate) and polycaprolactone are well-known representatives of this group of materials. They possess desirable properties for 3D printing which make them promising materials in many areas of applications.

Comparative Environmental Life Cycle Assessment on Corn Starch Plasticization and Co-Plasticization Processes

Starch has overtaken the bioplastic market in developing thermoplastic starch-based blends and composite systems owing to its biodegradability and sustainability. Thermoplastic starch (TPS) development is mostly a two-stage process involving plasticizing starch and blending plasticized starch with a polymer. Most of the research focuses on improving the properties of the blend system through different methodologies, including various plasticizers and co-plasticizers. However, limited studies have analyzed the environmental effects of plasticizers or co-plasticizers and their processing. Thus, in this research, the environmental impact of starch plasticization processes performed by co-plasticization (glycerol–urea, glycerol–citric acid, and glycerol–succinic anhydride) and by conventional glycerol-based plasticization is compared through life cycle assessment (LCA). The results showed that glycerol–citric acid- and glycerol–succinic anhydride-based co-plasticization had a comparable environmental impact to traditional glycerol-based plasticization. In contrast, the glycerol–urea-based co-plasticization process exhibited the highest effect on the environment. Furthermore, to reduce the environmental impact, a sensitivity analysis of the plasticization processes was conducted by changing the energy aspect of the processes through quantitative and qualitative approaches. The qualitative approach significantly reduced major impact categories such as global warming, carcinogens, ecotoxicity, and fossil fuel depletion.

Effect of clays incorporation on properties of thermoplastic starch/clay composite bio-based polymer blends

In this study, thermoplastic starch (TPS) biofilms were developed using starch isolated from the seeds of Melicoccus bijugatus (huaya) and reinforced with bentonite clays at concentrations of 1%, 3%, and 5% by weight. Novelty of this research lies in utilizing a non-conventional starch source and enhancing properties of TPS through clay reinforcement. FTIR analysis verified bentonite’s nature of clays, while SEM analysis provided insights into morphology and agglomeration behavior. Key findings include a notable increase in biofilm thickness and elastic modulus with higher clay content. Specifically, tensile strength of biofilms improved from 2.5 MPa for pure TPS to 5.0 MPa with 5% clay reinforcement. The elastic modulus increased from 25 MPa (TPS) to 60 MPa (5% clay). Thermal stability also showed enhancement, with initial degradation temperature increasing from 110 °C for pure TPS to 130 °C for TPS with 5% clay. Water vapor permeability (WVP) tests demonstrated a decrease in WVP values from 4.11 × 10−10 g m−1 s−1 Pa−1 for pure TPS to 2.09 × 10−10 g m−1 s−1·Pa−1 for TPS with 5% clay, indicating a significant barrier effect due to clay dispersion. These results suggest that biofilms based on huaya starch and reinforced with bentonite clay have considerable potential for sustainable food packaging applications, offering enhanced mechanical and barrier properties.

Preparation of PBAT microplastics and their potential toxicity to zebrafish embryos and juveniles

The extensive use of traditional non-biodegradable plastics results in the generation of microplastics (MPs), forming a new pollutant that can pose significant environmental risks. Biodegradable plastics (BP) possess degradation properties and can partially replace conventional plastics, thereby reducing pollution. However, further investigation is needed into the toxicity of biodegradable microplastics (BMPs) on aquatic organisms. This study explores the toxic effects of PBAT microplastics (PBAT-BMPs) and microplastics produced from degradable PBAT/TPS (thermoplastic starch) composite film (PBAT/TPS-BMPs) on zebrafish embryos. Our findings indicate that the presence of microplastics on the embryo's surface increases with higher BMPs concentration. Nonetheless, PBAT-BMPs tend to aggregate and are blocked by the embryonic membrane, thus diminishing their toxic effects on the embryo. Acute toxicity experiments revealed that 30 mg/L of PBAT-BMPs significantly reduced the survival rate of zebrafish embryos, whereas PBAT/TPS-BMPs had a lesser effect on survival. Both types of BMPs influenced the hatching rate of the embryos, leading to prolonged incubation periods. Additionally, both types of BMPs impacted the locomotor behavior of zebrafish larvae, causing an increase in larval locomotor speed. However, these BMPs had little impact on larval body development and heartbeat behavior. Fluorescent microplastic tracer experiments demonstrated that PBAT-BMPs persisted in juvenile fish for at least 144 h and were difficult to metabolize and excrete. Our study aims to gain a better understanding of the potential effects of BMPs on aquatic ecosystems and biological health, as well as to propose effective strategies for reducing environmental pollution and protecting organisms.