PLA Blends Research Articles

Effect of carboxymethylated chitosan and cellulose acetate on mechanical properties of PLA blends for biomedical applications

Chitin and chitosan are versatile and valuable biomaterials, with chitosan being abundantly found in the exoskeletons of crustaceans, insects, arthropods, and mollusks. The chemical extraction of chitin involves a series of steps, including deproteinization, demineralization, and decolorization. Chitosan is often combined with various polymeric materials, and polymer blending can enhance the mechanical properties of the resulting bioproduct. In this study, composites of poly(lactic acid) (PLA) with chitosan (Ch) and cellulose acetate (CA) were successfully fabricated using extrusion and injection molding techniques. The chitosan content, ranging from 0 to 7.5 wt. %, was incorporated into the PLA matrix to assess the impact of filler content on the mechanical and morphological properties of the composites. The chitosan powder was first alkalized and then etherified to obtain modified chitosan, specifically o-carboxymethylated chitosan (O-CMCh). The addition of chitosan led to a reduction in tensile strength, flexural strength, modulus of elasticity, and impact strength. However, the hardness of the composite improved with the inclusion of chitosan. The mesoporous structure of chitosan was characterized using nitrogen adsorption and desorption measurements. Morphological analysis revealed that the composite containing 3.75 wt. % chitosan exhibited significantly less fracture surface compared to other composites.

The Development of Poly(lactic acid) (PLA)-Based Blends and Modification Strategies: Methods of Improving Key Properties towards Technical Applications-Review.

The widespread use of poly(lactic acid) (PLA) from packaging to engineering applications seems to follow the current global trend. The development of high-performance PLA-based blends has led to the commercial introduction of various PLA-based resins with excellent thermomechanical properties. The reason for this is the progress in the field of major PLA limitations such as low thermal resistance and poor impact strength. The main purpose of using biobased polymers in polymer blends is to increase the share of renewable raw materials in the final product rather than its possible biodegradation. However, in the case of engineering applications, the focus is on achieving the required properties rather than maximizing the percentage of biopolymer. The presented review article discusses the current strategies to optimize the balance of the key features such as stiffness, toughness, and heat resistance of PLA-based blends. Improving of these properties requires molecular structural changes, which together with morphology, crystallinity, and the influence of the processing conditions are the main subjects of this article. The latest research in this field clearly indicates the high potential of using PLA-based materials in highly demanding applications. In the case of impact strength modification, it is possible to obtain values close to 800 J/m, which is a value comparable to polycarbonate. Significant improvement can also be confirmed for thermal resistance results, where heat deflection temperatures for selected types of PLA blends can reach even 130 °C after modification. The modification strategies discussed in this article confirm that a properly conducted process of selecting the blend components and the conditions of the processing technique allows for revealing the potential of PLA as an engineering plastic.

Flame-retardant and tough poly(lactic acid) with well-preserved mechanical strength via reactive blending with bio-plasticizer and phosphorus derivative

With sustainable development, advanced poly(lactic acid) (PLA) with superior toughness and flame retardancy is highly demanded in various industries, but the current design strategies often fail to achieve such bioplastics. In this work, flame-retardant and tough PLA bioplastics with well-preserved thermal stability and mechanical strength and enhanced UV resistance and soil degradation are prepared by solvent-free, reactive blending of PLA, bio-based epoxidized soyabean oil (ESO) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO). With the introduction of 10.0 wt% ESO and 3.0 wt% DOPO, the resultant PLA/10E/3D bioplastic has a high tensile strength of 52.8 MPa, with 26.3 times and 67.5 % increases in elongation at break and impact strength compared to those of PLA due to the toughening effect of ESO and the rigid structure of DOPO. The superior toughness of PLA/10E/3D enables it to outperform previous flame-retardant PLA counterparts. PLA/10E/3D achieves a vertical burning (UL-94) V-0 classification and a limiting oxygen index (LOI) of 27.5 %, indicative of satisfactory flame retardancy. Compared with PLA, PLA/10E/3D maintains high thermal stability and shows significantly enhanced UV-protecting and soil degradation properties. Therefore, this work delivers a green and scalable reactive processing method to create flame-retardant, tough yet strong bioplastics with improved soil decomposition and UV resistance, which contributes to sustainable development.

Biobased rubber toughened poly(lactic acid) blend for sustainable packaging films: The role of optical purity of poly(lactic acid)

AbstractThis study investigates the novel effect of poly(lactic acid) (PLA) optical purity on PLA/liquid natural rubber (LNR) blend films fabricated by solution casting. An investigation was conducted to examine how different levels of PLA optical purity affect the mechanical, structural, morphological, thermal, and barrier properties of PLA/LNR films. Infrared spectroscopy analysis revealed that the D‐isomer content of PLA significantly affected the chemical interactions between the LNR and PLA. The favorable chemical interaction between the LNR and PLA with a high D‐isomer content also increased the elongation at break by 300%. Morphological investigations proved that the chemical interaction also improved the dispersion and reduced the size of the LNR droplets formed in the PLA matrix. Notably, while low D‐isomer PLA blends showed decreased crystallinity (Xc) upon LNR addition, high D‐isomer PLA blends exhibited increased Xc by 460%, leading to a 42% increase in oxygen transmission rate. Additionally, hydrolytic degradation of high D‐isomer PLA increased by 259% with increasing LNR content. Overall, optical purity of PLA plays an important role in determining the properties of PLA blends.

Investigating the reinforcing effect of jute fiber in a PLA & PBAT biopolymer blend matrix for advanced engineering applications: Enhancing sustainability with bioresources

Renewable and biodegradable jute fiber (JF) is strategically incorporated as reinforcement in the poly (lactic acid) (PLA)/ poly (butylene adipate-co-terephthalate) (PBAT) matrix through melt blending. The resulting composites are comprehensively characterized to assess their mechanical properties, thermal stability, and morphological features. Scanning electron microscopy (SEM) is employed to scrutinize the interfacial bonding between the jute fibers and the biopolymer blend matrix. "The impact properties of the PLA/PBAT/JF 15 % composite (PLA/PBAT reinforced with 15 % jute fiber) are compared with a commercially available car dash box. Additionally, a composite fabricated from the recycled car dash box reinforced with 15 % jute fiber is evaluated. The results indicate that the developed composite demonstrates compatibility comparable to Acrylonitrile Butadiene Styrene (ABS) based engineering plastics." This investigation offers insights into the potential of bio-inspired jute fiber reinforcement to enhance the properties of the PLA/PBAT biopolymer blend matrix, thereby increases the scope in engineering applications other than single use application.

Exploring the performance of bio-based PLA/PHB blends: A comprehensive analysis

Poly(lactic acid) (PLA) is a bio-based linear aliphatic polyester that is broadly used in biomedical applications. A shortcoming of PLA is its brittleness and low toughness. Poly(hydroxybutyrate) (PHB) is a microbial bioprocessed and biodegradable polyester. To enhance toughness of PLA, it was melt-blended with PHB-based thermoplastic elastomer in various proportions by using a twin-screw extruder. Scanning electron microscope images reveal that PLA forms a continuous phase in PLA/PHB blends reinforced with inclusions of PHB. Fourier transform infrared spectroscopy measurements demonstrate strong intermolecular interactions between PLA and PHB chains. Differential scanning calorimeter thermogramms show that PHB reduces the glass transition temperature of PLA and affects its crystalline structure. When the mass fraction of PHB was 20, the glass transition temperature of the blend decreased to 33.9°C. Rheological measurements demonstrate that blending of PLA with PHB changes qualitatively the dependence of its viscosity on shear rate. Quasi-static (uniaxial tension) and dynamic (impact) tests confirm that blending of PLA with PHB results in a noticeable (by a factor of three) increase in its impact toughness and causes transition from the brittle to ductile regime of fracture. When the mass fraction of PHB was 40, the impact toughness reached to 0.40 kJ/m2, almost 3 times to neat PLA.

Co-pyrolysis of poly (lactic acid) and sugar cane bagasse: Kinetic and thermodynamic studies

For the purpose of investigating the effect of biomass on pyrolysis degradation of plastic wastes, poly (lactic acid) (PLA) has thus been attempted in present work to study the influence of sugar cane bagasse (SCB) on its pyrolysis behaviors and kinetic paramerizations. PLA/SCB samples after prepared by using a suspension blending method have been co-pyrolyzed in nitrogen by non-isothermal thermogravimetric analysis. After adding SCB biomass, the initial pyrolysis degradation temperatures and melting point of PLA are found to have declined substantially. Using pyrolysis results, activation energies of Ea are isoconversionally calculated by applying differential Friedman, integral Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, Starink and Vyazovkin-Dollimore methods, resulting in 113.7 ∼ 141.7, 101.3 ∼ 140.4 and 79.8 ∼ 210.1 kJ/mol for the PLA blends with 10, 20 and 30 mass% of SCB, respectively. Two approaches based on the Friedman differential equation along with integral methods are attempted for determining pre-exponential factor lnA and pyrolysis reaction model f(α). With these modeled results, the experimental curves are matched successfully. Moreover, thermodynamic parameters including ΔH, ΔG, and ΔS values were calculated for the entire pyrolysis process of three blends. The findings acquired from present study are of significance for advancing the design of any relevant pyrolysis reactor for PLA/biomass wastes.

3D‐printed PLA/PMMA polymer composites: A consolidated feasible characteristic investigation for dental applications

AbstractThis research article focused on the blending of poly(lactic acid)/poly(methyl methacrylate) (PLA/PMMA) polymer materials to overcome PLA's inherent weaknesses, such as low glass transition temperature, brittleness, and lack of melt strength. Consolidated feasible characteristic investigations, such as mechanical, thermal, and aging behavior, were carried out for PLA/PMMA blended polymer materials. Initially, the miscibility of PLA/PMMA blend filaments was prepared at various blend ratios (91/9, 82/18, and 73/27) and samples were printed by fused deposition modeling (FDM). Differential scanning calorimetry (DSC) and Fourier infrared spectroscopy (FTIR) analysis have been utilized to evaluate the glass transition temperature (Tg) and intermolecular interaction, respectively, on blended polymer materials. Experimental tensile, compression, and flexural strength testing were performed on neat polymers and blended polymer composites. Compared to neat PLA materials, blended composites had 13.24% and 19.07% higher flexural and compression strengths. Besides, the interfacial interaction of neat and blended polymers has been done using dynamic mechanical analysis (DMA). Furthermore, Tg, storage modulus, and aging behavior of blended polymer materials have significantly improved over neat PLA materials. Altogether, the development of PMMA/PLA blends as sustainable biomaterials for dental applications aligns with environmental concerns and the need for biocompatible materials in dentistry.Highlights Blending of PLA and PMMA helps mitigate the inherent constraints of PLA. Blended composites exhibited greater compressive and flexural strengths. Better glass transition temperature and intermolecular interaction. Excellent thermal stability and water aging imply viable dental biomaterials.

Innovative materials based on physical melt-blending of cutin from tomato waste and poly(lactic acid)

In the last decades, the improving and the progresses achieved following the principles of circular economy have unveiled virtuous approaches towards environmental challenges regarding the industrial processes. Agri-food waste constitutes a promising starting material for the design of innovative products with a marked improvement of the cradle-to-grave dynamics. In this scenario, the recovery of cutin from tomato peels waste represents an effective example of circular economy.In this work, the feasibility of the discontinuous melt-blending of cutin with poly(lactic acid) (PLA) was evaluated in order to obtain an innovative green material. Different blends of PLA and cutin have been characterized by using a multi-technique approach (FT-IR, DSC, TGA, SEM, rheological study, water vapour permeability) to achieve information on the nature and properties of these new materials. An important decrease of the final torque of the melt blends was observed, together with a decrease of the melt viscosity. Further increase in the cutin content in the blends was associated to a change in the viscosity of the melt. The addition of cutin to the PLA matrix caused a variation in the water vapour permeability, in accordance with the hydrophobic nature of the cutin.The obtained results attested that some degradation phenomena occurred along the process; however, the processability of these new blends is not impaired. The potential applications of these materials will mainly concern the agricultural sector and the production of degradable products with low environmental impact.

Synergistic effects of nucleating agent, chain extender and nanocrystalline cellulose on PLA and PHB blend films: Evaluation of morphological, mechanical and functional attributes

The current study focuses on reactive extrusion of poly (lactic acid) (PLA) and polyhydroxybutyrate (PHB) based blend films using epoxide styrene–acrylic (ESA) chain extender, pentaerythritol (PEOL) as a nucleating agent and cellulose nanocrystal (CNC). The blown films were subjected to various mechanical, thermal, barrier, and microstructural analyses to determine their suitability for packaging. Test results indicated that the incorporation of 0.5 wt% of chain extender significantly improved the elastic modulus and yield strength of PLA/PHB blend films. Further addition of 1 wt% of PEOL improved the crystallinity as well as mechanical strength in the films. FTIR analysis suggested chain conformations in different crystalline regions of PLA/PHB blend films whereas nucleation density and arrangement in crystal growth have been analysed by POM and SEM micro graphical studies. Additionally, the presence of CNCs within the PLA/PHB blend films showed an improved water vapour transmission rate (WVTR) of 90.53 g/m2.day revealing the creation of a tortuous path. Evaluation of optimum glossiness and haze of the films were done and the co-efficient of friction analysis depicted more anti-slip properties of the films.

Toughening poly(lactic acid) with novel polyolefin-graft-poly(lactic acid) copolymers maintaining high transparency and stiffness

The combination of well-balanced mechanical performance, high transparency and appealing eco-friendly attributes endows poly(lactic acid) (PLA) with significantly potential for wide-ranging applications in high-value packaging sectors. However, effectively toughening PLA without compromising its transparency and stiffness remains a formidable challenge. In this study, we synthesized a series of graft copolymers by incorporating hydroxyl-functionalized linear low density polyethylene (LLDPEOH) and copolymers of cycloolefin (COCOH) as the main chain and PLA as the side chain, which were subsequently employed as novel toughening agents for commercial PLA. The achievement of high-performance PLA blends with a balanced combination of toughness, strength, and transparency can be realized through meticulous tuning of the structure and mass fraction of the blended graft copolymers. The maximum elongation at break for the PLA blends increased by about 50 times that of neat PLA, reaching up to 300 %. Furthermore, these materials retained their high strength (54 MPa) and excellent transparency (light transmittance up to 90 %). The excellent properties of PLA blends could be ascribed to the well-designed chain structure of the graft copolymer which leaded to and excellent compatibility with the PLA matrix and unique phase morphology. This work is significant in guiding the design and synthesis of graft copolymers as toughening agents for PLA, thereby expanding its application range in areas where high transparency and toughness are required.

Biodegradable poly(lactic acid)/poly(propylene carbonate) blend with enhanced mechanical properties and heat resistance by uniaxial pre‐stretching

AbstractBiodegradable poly(lactic acid)/poly(propylene carbonate) (PLA/PPC) blends with balanced strength, ductility, and heat resistance were prepared by combining the modification of 30 wt% PPC and uniaxial pre‐stretching at 60°C. The undrawn PLA/PPC blend fractured in a brittle way due to the network structure composed of cohesional entanglements. After pre‐stretching, the elongation at break was increased to 229.4% at pre‐stretching ratio (PSR) of only 0.5, which should be attributed to the destruction of the network structure of cohesional entanglements and the orientation of PPC component in PLA matrix. With the increase of PSR, the modulus, strength at yielding, and break were improved obviously (2433.4, 76.1, and 98.3 MPa at PSR = 2.5) whereas the elongation at break (51.7% at PSR = 2.5) reduced gradually because of the formation of orientation, mesophase, and crystal phase. However, the elongation at break was still larger than that of neat PLA (6.8%) and undrawn PLA/PPC blend (12.3%), indicating that the uniaxial pre‐stretching was an effect way to strengthen and toughen PLA blends. Significantly, the heat resistance of ps‐PLA/PPC blend was increased obviously with increasing the PSR, which will promote the widespread application of the blends.

A generalizable reactive blending strategy to construct flame-retardant, mechanically-strong and toughened poly(L-lactic acid) bioplastics

Poly(L-lactic acid) (PLA) is an environmentally-friendly bioplastic with high mechanical strength, but suffers from inherent flammability and poor toughness. Many tougheners have been reported for PLA, but their synthesis usually involves organic solvents, and they tend to dramatically reduce the mechanical strength and cannot settle the flammability matter. Herein, we develop strong, tough, and flame-retardant PLA composites by reactive blending PLA, 6-((double (2-hydroxyethyl) amino) methyl) dibenzo [c, e] [1,2] oxyphosphate acid 6-oxide (DHDP) and diphenylmethane diisocyanate (MDI) and define it PLA/xGH, where x indicates that the molar ratio of -NCO group in MDI to -OH group in PLA and DHDP is 1.0x: 1. This fabrication requires no solvents. PLA/2GH with a -NCO/-OH molar ratio of 1.02: 1 maintains high tensile strength of 63.0 MPa and achieves a 23.4 % increase in impact strength compared to PLA due to the incorporation of rigid polyurethane chain segment. The vertical combustion (UL-94) classification and limiting oxygen index (LOI) of PLA/2GH reaches V-0 and 29.8 %, respectively, because DHDP and MDI function in gas and condensed phases. This study displays a generalizable strategy to create flame-retardant bioplastics with great mechanical performances by the in-situ formation of P/N-containing polyurethane segment within PLA.

Fabrication of highly efficient biodegradable oligomeric lactate flame-retardant plasticizers for ultra-flexible flame-retardant poly (lactic acid) composites

Biobased multifunctional plastic additives not only overcome the toxicity and non-degradability of phthalates but also provide multiple functions to polymers. In this study, novel biodegradable oligomeric lactate flame-retardant plasticizers (PBCL) integrated from l-lactic acid and crotonic acid with excellent fire-retardant and plasticizing functions were synthesized to overcome the inflammability and fragileness of poly(lactic acid) (PLA). The results revealed that PBCL-plasticized PLA composites achieved a good balance between flexibility and fire retardancy. Even with a ratio of 0.2:1 of 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to 2-(2-n-butoxyethoxy) ethanol of crotonic acid lactate ester (BCL), the plasticized PLA blends showed the highest elongation at break (433.72 %), accompanied by a high limiting oxygen index (27.1 %). Remarkably, the vertical burning tests (UL-94) indicated that all blends passed UL-94 V-0 grade, signifying their superior fire resistance. Interestingly, the addition of PBCL had minimal impact on the transparency of PLA, with the transmittances of all composites still remained at above 87 % at 800 nm. Furthermore, the PBCL-plasticized PLA composites exhibited better migration resistance and volatility resistance than commercial plasticizer acetyl tributyl citrate (ATBC). Additionally, the biodegradability of PBCL was studied through the degradation experiments using active soil and tenebrio molitors, with characterization of the degradation products. The results of the biodegradation experiments showed that PBCL decomposed into non-toxic and harmless small molecules. This study presents an eco-benign method for developing biodegradable additives with flame-retardant and plasticizing functions, holding excellent prospects for industrial applications.

Toughness enhancement of polylactide with low amounts of poly (butylene adipate‐co‐terephthalate) through in situ reactive compatibilization

AbstractPolylactide (PLA) was melt blended with low amounts of poly (butylene adipate‐co‐terephthalate) (PBAT) using a simple reactive extrusion process herein, aiming to address the inherent brittleness of PLA without significantly compromising its stiffness. PLA/PBAT (90/10) blends with a small amount of peroxide (0.02 phr) and a second crosslinker agent triallyl isocyanurate (TAIC) were produced to explore the structure‐performance relationship evolution in reactive extrusion. The results showed that the PLA blend with an appropriate amount of TAIC (i.e., 0.3 phr) exhibited a remarkable increase in elongation at break, reaching as high as 96%. The sample with high elongation also demonstrated a high stiffness, boasting a Young's modulus of 2.4 GPa and a yield strength of 43 MPa. It was evident that the combination of enhanced compatibility and optimized homogeneous PBAT phase size of approximately 0.6 μm worked synergistically to enhance the toughness of PLA. Conversely, higher TAIC contents resulted in over‐crosslinking, despite considerable improvements in compatibility. This study offers a versatile, scalable, and practical method to prepare fully biodegradable PLA blends with high toughness.

A review on polylactic acid‐based blends/composites and the role of compatibilizers in biomedical engineering applications

AbstractPoly(lactic acid) (PLA) is one of the most promising biopolymers extensively used in food, packaging, medical and pharmaceutical industries. It is due to favorable physicochemical properties, in‐situ hydrolytic degradation and well‐established processing parameters. However, in medical engineering applications, PLA shows some drawbacks like low cell adhesion, biological inertness, slow degradation rate and high acid inflammation. These shortcomings of pure PLA could be addressed by blending it with other bioresorbable materials and compatibilizers. This review provides comprehensive information on different PLA composites in the field of tissue engineering, implants, injury management and drug delivery systems. The PLA‐based composites are divided into four parts: PLA/polymer, PLA/metal, PLA/ceramic, and PLA/nanoparticles. It also investigates various synthesis process, role of different compatibilizers, in vitro studies and their in vivo applications.Highlights Review the trends of bioresorbable PLA blends/composites. Extensively focused on PLA blend with polymer, metal, ceramic, and nanoparticles. Role of reinforcement and compatibilizer to overcome shortcomings of PLA implant. Highlights advantages, limitations, and properties of different types of PLA implants. Discuss various clinical applications and future of PLA blends/composite scaffolds.

PLA-Sago Starch Implants: The Optimization of Injection Molding Parameter and Plasticizer Material Compositions

Previous research extensively characterized PLA blends for various biomedical applications, especially in polymer-based biodegradable implant fixations, offering advantages over metallic counterparts. Nevertheless, achieving an optimal PLA mixture with both mechanical resistance and fast biodegradability remains a challenge. Currently, literature still lacks insights into the manufacturing parameter impact on sago starch/PLA in combination with PEG plasticizer. The objective of this study is to assess variations in injection molding temperatures and sago/PLA/PEG weight compositions to identify the optimal combination enhancing miniplate mechanical properties and biodegradation behavior. Mechanical tests reveal that incorporating PEG into pure PLA yields high mechanical performance, correlating linearly with increasing injection temperature. However, the interaction once the three materials are mixed decreases mechanical performance across tested temperatures. Higher biodegradation rates are observed with a larger weight composition of the hydrophilic behavior attributed to sago starch presence. The observed novelty in PLA mixed with 20% sago starch and 10% PEG at 170 °C indicates a better performance in elastic modulus and elongation at break also the degradation rate, emphasizing the role of injection temperature in molding miniplate implants. In conclusion, the interplay of injection molding parameters and material compositions is crucial for optimizing PLA-based miniplate implants, with potential contributions to tissue implants rather than bone implants due to their mechanical limitation.

Preparation and performance of super toughened and high heat-resistant biodegradable PLA/PBAT blends

Super toughened and high heat-resistant poly (lactic acid) (PLA)/poly (butylene-adipate-co-terephthalate) (PBAT) blends were synergistically prepared by compounding pre-prepared polyborosiloxane gel (PBSG) and multicomponent epoxy chain extender (ADR) with further heat-treatment. The effects of PBSG content on the performance and microstructure of the blends were investigated. The impact strength of the blends without heat treatment increased with the increase of PBSG content. After heat treatment, the impact strength of the blends showed a tendency of first increasing and then decreasing with the increase of PBSG content, and the maximum impact strength of the blends before and after the heat treatment was 56.51 kJ/m2 and 46.08 kJ/m2, respectively. The heat treatment could greatly improve the vicat soft temperature and thermo-mechanical properties of the blends. After the heat treatment, the vicat soft temperature of all the blends exceeded 150 °C, and the storage modulus of all the blends exceeded 100 MPa, and the annealed PLA blend beard a 20 g weight could kept at 100 °C for 12 h with negligible deformation, which attributed to the improvement of the interface properties and the crystallization properties.

Preparation and characterization of poly(vinyl alcohol)/poly(lactic acid) blends containing bio‐based plasticizers

AbstractThe bio‐based plasticizers‐glycerol and lactic acid were used to plasticize and compatibilize PVA/PLA blends during melt blending process. It was confirmed that lactic acid significantly improved the compatibility between glycerol‐plasticized PVA and PLA. Compared with pure PVA, the melting and crystallization temperatures and crystallinities decreased but the crystal form of PVA in the blends was not changed. The thermal stabilities of PVA/glycerol (G)/lactic acid (L)/PLA blends were better than PVA/G/PLA blends. Compared to PVA/G/PLA blends, the tensile and tear strength of PVA/G/L/PLA blends were improved, however, elongation at break decreased. The water absorptions and water vapor permeances of the blends decreased with the addition of hydrophobic PLA, but they increased by incorporation of hygroscopic lactic acid. The surface resistivities of the blends augmented in combination with PLA but declined by adding lactic acid. The melt flow rates of PVA/G/PLA blends were better than PVA/G/L/PLA blends because lactic acid enhanced the interactions among the components. After the addition of lactic acid, the transmittances of the blends increased due to the refined dispersed phases by the compatibilization. The compatibility between the components was predicated by Hansen solubility parameters. These blends showed potential as a novel barrier material for food and medicine packages.Highlights PVA, glycerol, and PLA blends were compatibilized by lactic acid. The melting temperatures decreased with addition of glycerol and lactic acid. The tensile and tear strengths were enhanced with addition of PLA and lactic acid. The hydrophobicity, melt fluidity, and surface resistivity were improved by PLA.

The Effect of Mechanical Recycling on the Thermal, Mechanical, and Chemical Properties of Poly (Butylene Adipate-Co-Terephthalate) (PBAT), Poly (Butylene Succinate) (PBS), Poly (Lactic Acid) (PLA), PBAT-PBS Blend and PBAT-TPS Biocomposite

Mechanical recycling of plastics is regarded as the best option to minimize plastic waste pollution in the environment as it is well established and offers valorisation of plastics; however, there is limited research on the mechanical recyclability of biopolymers. This work aimed to evaluate the effect of multiple reprocessing on the mechanical, thermal, physical, chemical, and morphological properties of poly (butylene adipate-co-terephthalate) (PBAT), poly (butylene succinate) (PBS), poly (lactic acid) (PLA), PBAT-PBS blend, and PBAT-thermoplastic starch (TPS) composite. Low-density polyethylene (LDPE), a conventional non-biodegradable plastic, was also reprocessed for comparison studies. The biopolymers were extruded seven times in a twin-screw extruder and injection moulded into test specimens. Their properties were investigated at each extrusion cycle. Tensile, impact strength, and melt flow index (MFI) results of neat PBAT and PBAT-TPS were stable with slight changes throughout the seven reprocessing cycles and were comparable to LDPE. The properties of PBS, PLA, and PBAT-PBS blend, on the other hand, started to decrease after the second melt extrusion cycle. In addition, differential scanning calorimetry (DSC), thermogravimetry (TGA), and dynamic mechanical analysis (DMA) results showed that LDPE, PBAT, and PBAT-TPS exhibited better thermal and mechanical stability as compared to PBS, PLA, and PBAT-PBS blend. The FTIR spectroscopy results showed that the characteristic peaks of C=O and C–O around 1710 cm−1 and 1046–1100 cm−1 for PBS, PLA, and PBAT-PBS decreased due to multiple thermal processing, while those of PBAT and PBAT-TPS were unaffected. Scanning electron microscopy (SEM) micrographs of the fractured cross-sectional surface of PBS, PLA, and PBAT-PBS tensile specimens clearly evidenced the degradation of the biopolymers by severely fractured morphology as a result multiple reprocessing cycle. The results demonstrate that the fully biodegradable PBAT and PBAT-TPS can be mechanically recycled for at least seven cycles, and therefore, the service life of biodegradable polymers can be extended, and it is comparable with petroleum-based plastic.Graphical