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Numerous zinc complexes based on N‐ and O‐donor Schiff‐base ligands have shown great promise in the ring‐opening polymerization (ROP) of lactides, which are cyclic dimers of lactic acid, to produce poly(lactic acid) (PLA). This is primarily because zinc is a borderline metal, making it non‐cytotoxic, inexpensive, abundant, biocompatible, and environmentally safe. Additionally, Schiff‐based ligands offer stability, stereoselectivity, desirable electronic and steric environments, and resistance to impurities. As a result, zinc complexes are easy to synthesize, colourless, have high reactivity and solubility in organic solvents, and are manageable under typical circumstances. Furthermore, these complexes are free to adopt a variety of coordination numbers since zinc does not have ligand field stabilization energy (LFSC). Zinc complexes possess high catalytic activity due to their distinctive properties, including high Lewis acidity, high electron transfer ability, stability concerning the reactive intermediate, and the ability to monitor polymerization by nuclear magnetic resonance (NMR) spectroscopy. Moreover, these complexes also have reasonable control over stereochemistry, number‐average molecular weight (Mn), and dispersity index (Ð). These advantages make it possible to produce colourless PLA with a high yield, high molecular weight, and narrow dispersity index in bulk and solvent‐based conditions. [ABSTRACT FROM AUTHOR]

The development of triboelectric nanogenerators (TENGs) using sustainable materials addresses the global electronic waste issue. This research focuses on fabricating a TENG device with biodegradable polylactic acid (PLA) as the tribopositive material and polytetrafluoroethylene (PTFE) as the tribonegative material. ZnFe2O4 nanoparticles are incorporated into the PLA matrix to enhance surface charge density and synthesised via a simple combustion method. PLA-ZnFe2O4 composite films were prepared by solvent casting with varying nanofiller content (0.25, 0.45, 0.65, and 0.85 g). Prepared composites were characterised by Powder X-ray Diffraction (PXRD) for crystalline nature and phase purity, Fourier Transform Infrared Spectroscopy (FTIR) for vibrational analysis, and Scanning Electron Microscopy (SEM) for surface morphology. The inclusion of ZnFe2O4 nanoparticles improves TENG output performance, with a maximum output voltage of 18.4 V and a current of 1.57 µA observed for a PLA (poly(lactic acid)) composite with 39.39% nanoparticle content. Electrical studies on the optimised device show successful charging of various capacitors and powering 20 LEDs and a calculator. Body movements like walking and jumping were also tested to measure voltage and current outputs. These findings highlight new possibilities for developing smart, self-powered electronic devices. [ABSTRACT FROM AUTHOR]

This 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. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The design of eco‐friendly active food packaging systems based on biobased polymeric materials is a growing field of research because of the pressing concern for sustainable development. Herein, monolayer ternary thermoplastic films composed of poly(lactic acid) (PLA), gallic acid (GA, 2.5% w/w relative to PLA), and a plasticizer (poly(ethylene glycol) [PEG] or epoxidized linseed oil [ELO], 5.0 and 7.5% w/w relative to PLA) are prepared via melt‐mixing followed by compression molding. The ensuing plasticized and self‐standing PLA/GA films are translucent and have good mechanical properties (Young's modulus ~2 GPa) and welding performance. The incorporation of GA yields films with ultraviolet‐light barrier properties (transmittance below 40%, 200–400 nm), antioxidant capacity (radical scavenging activity above 94%), and antibacterial activity against the methicillin‐resistant strain of Staphylococcus aureus (minimum of 3‐log reduction colony forming units mL−1). These thermoplastic films are easily degradable via enzymatic degradation with proteinase K from Tritirachium album, reaching weight loss values of 100% after 9 days. The films plasticized with PEG present slightly better antibacterial action and enzymatic degradation, whereas those plasticized with ELO exhibit marginally higher surface hydrophobicity and thermal stability. Thus, the combination between PLA and GA yielded biobased films with bioactive properties that have potential for application in active food packaging. [ABSTRACT FROM AUTHOR]

Amid the current environmental crisis caused by plastic accumulation, one of the proposed solutions to manage this problem is using biodegradable polymers. However, the impact of adding biodegradable polymers to the well-established circular economy of recyclable polymers, such as HDPE, has not been fully considered. Therefore, there is a need to reconsider the way we consume, dispose of, and manage biodegradable polymers after use. This study evaluates the effect of varying the contents of a biodegradable polymer, taking poly(lactic acid) (PLA) as a model biodegradable polymer, on the thermal and mechanical properties of HDPE. The study highlights the importance of identifying and disposing of biodegradable polymers to avoid mixtures with HDPE, in order not to affect mechanical performance when considering reprocessing and a new life cycle of this conventional polymer. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) is known to exhibit slow crystallization. Therefore, post‐process annealing is often performed, at which structure change is inevitable. In this paper, the structure development during annealing of PLA containing N,N′‐ethylenebis(12‐hydroxystearamide) (EBHS) is studied using extruded strands. First, EBHS, which acts as a nucleating agent, is dissolved in molten PLA, and then segregates with a fibrous shape during cooling. Next, the PLA containing EBHS is extruded, which causes EBHS fibers in the strand to orientate with the flow direction. When the strand is annealed at 100°C, amorphous PLA chains initially lose their orientation. Then, the chain orientation in the PLA strand develops because of transcrystallization from the surface of EBHS fibers that are aligned with the flow direction. As a result, the Hermans orientation function increases from 1.8 × 10−3 (before annealing) to 6.0 × 10−3 (after annealing). Moreover, the annealed PLA/EBHS strand shows less shrinkage (0.80 ± 0.19%) than the annealed PLA strand (2.04 ± 0.27%). The promotion of PLA chain orientation induced by the presence of aligned EBHS fibers can be used to control the structure and dimensional change of PLA products during annealing. [ABSTRACT FROM AUTHOR]

The objective of the present work was to explore the effects of accelerated weathering test on properties of poly(lactic acid) (PLA)/poly(butylene adipate- co -terephthalate) (PBAT) blend and PLA)/PBAT/wood flour (WF)/wollastonite (WT) composite. The 70/30 (wt%/wt%) PLA/PBAT blend and its composite with 25 phr WF and 5 phr WT were prepared on a twin screw extruder and injection molding machine. Resulted blend and hybrid composite were exposed to accelerated weathering conditions of UV-irradiation and moisture cycles at 63°C in a laboratory Xenon Weather-Ometer chamber for various periods (250, 500, 750, and 1000 h). The alterations in the surface quality (color change), chemical structure, surface morphology, tensile properties, thermal behaviors, and thermal stability of the specimens were evaluated by spectrocolorimetry, Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM), universal testing machine, differential scanning calorimetry and thermogravimetric analysis, respectively. The photo- and hydrolytic degradations were found to occur during the weathering exposure time. Both blend and composite showed a continuous increase in the total color change with prolonged exposure time, which was mainly due to the degradation of PLA and wood components, especially lignin. The SEM images also confirmed their degradations by illustrating roughness, voids, and cavities on the specimen surfaces after accelerated weathering. Meanwhile, the tensile and thermal properties of both blend and composite were found to decrease. Thus, this study can be used for quality control and material certification. [ABSTRACT FROM AUTHOR]

Highlights Currently, toughening poly(lactic acid) (PLA) without reducing its strength and modulus is still challenging. Fortunately, this problem could be addressed by incorporating cellulose nanocrystals grafted with epoxidized soybean oil (CNCs‐g‐ESO) into the PLA matrix. The percolation threshold for uniform dispersion of the CNCs‐g‐ESO in the PLA matrix was about 0.8 wt%. The loading made the elongation at break and tensile fracture energy of the PLA composite film increase to 26.5 and 11.26 from 3.7% and 0.96 MJ.m−3, respectively, concerning the neat PLA. Meanwhile, it also resulted in a 4.7% and 12.4% increase in the tensile strength and Young's modulus, respectively. Additionally, the initial decomposition temperature (T5%) of the PLA composite increased to 334.9 from 316.1°C after incorporating the CNCs‐g‐ESO. Therefore, the CNCs‐g‐ESO, acting as an ESO‐like plasticizer and a CNCs‐like nucleating agent, is a potential nanofiller for reinforcing and toughening PLA. Cellulose nanocrystal grafted with epoxidized soybean oil (CNCs‐g‐ESO) The CNCs‐g‐ESO acting as both plasticizer and nucleating agent The CNCs‐g‐ESO decreasing the spherulite size, but increasing the CrI of PLA The CNCs‐g‐ESO enlarging the window for thermal process of PLA Simultaneous reinforcement and toughness of PLA [ABSTRACT FROM AUTHOR]

Agricultural activities contribute to numerous waste problems and have emerged as a significant environmental concern. Nondegradable plastic residues decompose, releasing microplastics and affecting ecosystems and the environment. Consequently, biodegradable bio-composite films consisting of polylactic acid (PLA), natural rubber (NR), and rice straw (RS) have been developed with the aim of using them in agricultural applications. In this study, the PLA/NR blend, at a fixed ratio of 60/40 wt%, was filled with 3 and 5 wt% RS powder and extruded through a slit die into films. The biodegradability of all films was examined after being buried for 90 days in soil with a moisture content of 30% by weight. The neat PLA film showed the lowest weight loss percentage, 3.33%, suggesting a comparatively slower degradation rate in comparison to the PLA/NR(60:40) blend and all bio-composite films. The presence of 40 wt% NR in the film helped accelerate the biodegradation process during soil burial. The film produced from PLA/NR 60:40 wt% matrix filled with RS at 5 wt% led to rapid degradation, leading to a weight loss of 8.30%. From SEM micrographs, the morphology of all polymers after burial in soil showed fractures, the formation of pores, and obvious surface indications of fungi growing. The content of carbon decreased after soil burial, while oxygen content increased, and nitrogen was detected. The XRD analysis revealed low crystallinity in the neat PLA, consistent with the DSC analysis. The addition of NR and RS to the composites led to an increase in the crystallinity of PLA phase. All investigated materials exhibited an increase in crystallinity after being buried in soil. This research demonstrates that bio-composite films manufactured from the PLA/NR(60:40) blend filled with RS degrade more easily than unmodified PLA film. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The conducted study was focused on the development of a new type of technical blend reinforced with natural fillers. The study was divided into two parts, where, in the first stage of the research, unmodified POM was reinforced with different types of natural fillers: cellulose, wood flour, and husk particles. In order to select the type of filler intended for further modification, the mechanical characteristics were assessed. The 20% wood flour (WF) filler system was selected as the reinforcement. The second stage of research involved the use of a combination of polyoxymethylene POM and poly(lactic acid) PLA. The POM/PLA blend (ratio 50/50%) was modified with an elastomeric compound (EBA) and chain extender as the compatibilized reactive (CE). The microscopic analysis revealed that for the POM/PLA system, the filler–matrix interface is characterized by better wettability, which might suggest higher adhesion. The mechanical performance revealed that for POM/PLA-based composites, the properties were very close to the results for POM-WF composites; however, there is still a significant difference in thermal resistance in favor of POM-based materials. The increase in thermomechanical properties for POM/PLA composites occurs after heat treatment. The increasing crystallinity of the PLA phase allows for a significant increase in the heat deflection temperature (HDT), even above 125 °C. [ABSTRACT FROM AUTHOR]

The study investigated the biological properties of a composite material composed of poly(lactide) (PLA) and iron (Fe) produced by sputtering iron onto melt-blown poly(lactide) nonwoven fabrics. The research aimed to thoroughly understand the structure and properties of these materials and their potential applications in biomedicine. We conducted comprehensive chemical and structural analyses using techniques such as microscopic analysis, flame atomic absorption spectrometry (FAAS), and Brunauer–Emmett–Teller (BET) surface area analysis to precisely determine the properties of PLA-Fe materials. Additionally, we evaluated their impact on blood coagulation processes by measuring activated partial thromboplastin time (aPTT) and prothrombin time (PT). We also performed biological analyses on human peripheral blood mononuclear cells (PBM cells) including cell viability and DNA damage. Our results clearly demonstrate that PLA-Fe materials do not significantly influence blood coagulation mechanisms, as they only slightly prolong aPTT time and have no effect on PT. This suggests their potential in biomedical applications. Our results indicate the absence of cyto- and genotoxic properties of PLA-Fe materials against normal blood cells. In conclusion, the research findings suggest that the novel poly(lactide) and iron-sputtered nonwoven fabrics are promising tools in the field of biomedicine, offering potentially innovative therapeutic solutions for the treatment of wounds and injuries. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polylactic acid (PLA), derived from renewable resources, has the advantages of rigidity, thermoplasticity, biocompatibility, and biodegradability, and is widely used in many fields such as packaging, agriculture, and biomedicine. The excellent processability properties allow for melt processing treatments such as extrusion, injection molding, blow molding, and thermoforming in the preparation of PLA‐based materials. However, the low toughness and poor thermal stability of PLA limit its practical applications. Compared with pure PLA, conditions such as processing technology, filler, and crystallinity affect the mechanical properties of PLA‐based materials, including tensile strength, Young's modulus, and elongation at break. This review systematically summarizes various technical parameters for melt processing of PLA‐based materials and further discusses the mechanical properties of PLA homopolymers, filler‐reinforced PLA‐based composites, PLA‐based multiphase composites, and reactive composite strategies for PLA‐based composites. [ABSTRACT FROM AUTHOR]

Polymer blends of poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) and high-density polyethylene (HDPE) with different blend ratios were prepared by a melt blending method. The thermal, morphological, mechanical, opacity, and biodegradation properties of the PLLA-PEG-PLLA/HDPE blends were investigated and compared to the PLLA/HDPE blends. The blending of HDPE improved the crystallization ability and thermal stability of the PLLA-PEG-PLLA; however, these properties were not improved for the PLLA. The morphology of the blended films showed that the PLLA-PEG-PLLA/HDPE blends had smaller dispersed phases compared to the PLLA/HDPE blends. The PLLA-PEG-PLLA/HDPE blends exhibited higher flexibility, lower opacity, and faster biodegradation and bioerosion in soil than the PLLA/HDPE blends. Therefore, these PLLA-PEG-PLLA/HDPE blends have a good potential for use as flexible and partially biodegradable materials. [ABSTRACT FROM AUTHOR]

In this study, a twin-screw extruder was used to fabricate poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends and blend-based nanocomposites with carbon nanotube (CNT) or nanocarbon black (CB) as nanofillers. The fabricated samples were subsequently treated with supercritical carbon dioxide (scCO2) to fabricate the corresponding foams. Bi-phasic morphology and selective distribution of CNTs or CBs in the PBAT phase were observed in the blends/composites through scanning electron microscopy. After the scCO2 treatment, the selective foaming of the PBAT phase in the prepared blends/composites was confirmed. The cellular structure of PBAT phase in scCO2-treated blends is similar to the size/shape of PBAT domains in untreated blends or treated neat PBAT foam. The addition of CNTs or CBs in the blends led to a slight reduction in cell size of the foamed PBAT phase, demonstrating CNT/CB-induced cell nucleation. Differential scanning calorimetry (DSC) results showed that CNTs and CBs played as nucleating agents and increased the initial crystallization temperature up to 14 °C compared with neat PBAT for PBAT in different composites during cooling. The scCO2 treatment induced the bimodal stability of PBAT crystals in different samples, which melted mainly in two temperature regions in DSC studies. Thermogravimetric analyses revealed that compared with parent blends, the addition of CNTs or CBs increased the temperature at 80 wt.% loss (degradation of PBAT portion) up to 6 °C. The electrical resistivity decreased by more than six orders of magnitude for certain CNT- or CB-added composites compared with the parent blends. The hardness of the blends slightly increased after forming the corresponding composites and then declined after the scCO2 treatment. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) is a biodegradable polymer with limited application because of its intrinsic brittleness, low toughness, and low elongation at break. Melt blends were prepared by mixing a natural rubber (NR, poly(1,4‐cis‐isoprene) in the form of liquid NR (LNR), liquid‐epoxidized NR (LENR), and polypropylene (PP) in the PLA matrix. Four blend systems were designed and prepared, i.e., PLA–PP, PLA–PP–LNR, and PLA–LNR or PLA–LENR. The composition of PP in the blend was fixed at 10 % PLAPP (90/10). Results showed that PLA–PP mixed with LNR improved impact and elongation at break. The binary blend of PLA–LNR (90/10) significantly enhanced impact strength and elongation at break properties. In contrast, the binary blends of PLA–LENR (90/10) showed a lower value of elongation at break (9.5 % vs. 37.3%) and impact strength (4.56 kJ m−2 vs. 6.44 kJ m−2). The melting temperature (Tm) and the glass transition temperature (Tg) were measured by differential scanning calorimetry, which recorded slight changes in the glass temperatures and melting temperatures. Scanning electron microscopy images of the tensile fracture of the PLA–LNR (90/10) blend showed the presence of large fibrils associated with the ductile failure related to neat PLA. Finally, the fracture toughness (KIC) of PLA–LNR (90/10) showed an increase of 39 % over neat PLA (2.94 MPa.m1/2 vs. 4.08 MPa.m1/2). [ABSTRACT FROM AUTHOR]

Increasing toughness of brittle polymer without losing modulus of elasticity and tensile strength is highly important for enlarging the range of applications. In this study, polylactic acid (PLA) modified with epoxidized linseed oil (ELO) and polypropylene-grafted maleic anhydride (PPgMA) with a good balance of toughness and rigidity was successfully prepared by melt mixing procedure. The addition of PPgMA/ELO with appropriate proportions (3:1, 5:1, and 5:5 wt %) resulted in PLA modified samples with significant ductility improvement (around 2200% of elongation at break and 1800% of tensile toughness compared to the neat PLA) with low decrease in Young modulus and tensile strength. This feature was attributed to improved interfacial interactions and the formation of crosslinked structures at the interface that also increased viscosity of the melting system and cold crystallization temperature of PLA. The scanning electron microscopy revealed the presence of small domains of modified systems. The effectiveness of reactive compatibilization among the components was also suggested by Fourier transform infrared (FTIR) spectroscopy and thermal degradation analysis. The combination of toughness, modulus of elasticity and good thermal properties make this low-cost and scalable ecofriendly material a promising candidate for use as biodegradable plastic in several fields including medical applications and packaging. [ABSTRACT FROM AUTHOR]

Global regulations are guiding society towards more sustainable material solutions. This increasing awareness of the need for environmentally friendly alternatives has led to a greater emphasis on biocomposites, which combine natural fibers with bio-based polymers. This study investigates how bleached softwood pulp fibers (BSWPF) and unbleached softwood pulp fibers (UBSWPF) affect the characteristics of poly(lactic acid) (PLA)-based biocomposites. UBSWPF is a more cost-effective option because it is manufactured with less processing steps than BSWPF. However, it is largely unexplored as a reinforcement in biopolymers. Through investigating the mechanical, thermal, and morphological aspects of the biocomposites, this study showed that UBSWP increased the modulus and impact strength of the PLA biocomposites better than BSWPF. The impact strength, modulus, and tensile strength of PLA-BSWPF and PLA-UBSWPF improved as the fiber content increased. However, a decrease in tensile strength was seen at higher percentages of UBSWPF in PLA. Despite the decrease in tensile strength at higher UBSWPF concentrations, both types of fibers improved the mechanical properties of the biocomposites, demonstrating a potential sustainable reinforcing material for PLA biocomposites. [ABSTRACT FROM AUTHOR]

In recent years, there has been continuous growth in the market for polylactide/poly(lactic acid) (PLA) which can be attributed to the increasing preference for environmentally friendly products derived from renewable resources. Apart from its established biomedical applications, polylactide is being considered as a replacement for petroleum-based polymers in various industries, including packaging, electronics, automotive, and textiles. However, PLA modification is necessary to meet the properties of common thermoplastics for target applications. One of the modification methods involves the synthesis of PLA block copolymers, including widely exploited polymers of vinyl monomers (PVM). This review article covers a wide range of applications suggested for PLA/PVM block copolymers as discussed in recent articles. A brief overview of the synthesis methods for PLA/PVM block copolymers is provided. The tendency of block copolymers to self-assemble, leading to specific morphologies, is discussed, and applications that take advantage of this behavior, such as polymeric micelles or porous materials, are highlighted. Examples of using micelles for the delivery of biologically active compounds are presented. Other biomedical applications, such as materials for tissue engineering and medical devices, are also discussed. Finally, the article covers materials for common plastic applications obtained through reactive blending/extrusion, which produces PLA/PVM copolymers in situ. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) was injected into test sheets and then dipped in a suspension of xylene and trimethylol propyl silane (95/5) containing titanium dioxide (TiO2) nanoparticles (NPs) at 65 and 85 °C for 3, 7, 10 and 15 s. TiO2 NPs aggregates coated the sheet surfaces after dipping. The camera photos and the static water contact angle (WCA) showed that the dip-coating transformed all the hydrophilic surfaces into hydrophobicity, and especially that the sheet with retention of 85 °C and 7 s exhibited superhydrophobicity, while the water droplets on the 65 °C sheets were in pinning state. The water droplets rolled off the superhydrophobic surface at tilt angles below 3°, showing self-cleaning. The retention period of 7 s was suitable, as it achieved the highest surface hydrophobicity regardless the retention temperature. The images of scanning electron microscope (SEM) and optical microscopes demonstrated the deposition of TiO2 NPs aggregates on the sheet surface and the formation of the porous structure on the surface. The combination of the aggregates with nanoscale protrusions and the pores with nanoscale pore walls constituted a hierarchical structure. The retention temperature of 65 °C made the pores shallow and wide, and the TiO2 concentration of 2% instead of 1% caused the excessive TiO2 NPs aggregates to cover the PLA substrate, reducing the WCA. The wetting models of water droplets on the surfaces of the 65 and 85 °C sticks were classified as Wenzel and Cassie states, respectively. [ABSTRACT FROM AUTHOR]

Considerable interest in food packaging research has been prompted by the rising environmental impact of waste, customer awareness for readily accessible foods with extended shelf life, and ecological consciousness about the scarcity of natural resources. The utilization of plastic-based food packaging has resulted in a significant environmental concern due to the accumulation of substantial quantities of plastic in the surrounding areas. Research efforts are being motivated by ecological and health considerations in the pursuit of developing biodegradable films. Besides, poly(lactic acid) (PLA) has been suggested as a possible substitute for petroleum-based polymers because of its sustainability, simple accessibility, and biodegradability. PLA is a biodegradable plastic made from sugar beet or maize starch that may be fermented by bacteria to generate material with desirable qualities like transparency and rigidity. However, there is a need for further improvement in certain properties of PLA, such as flexibility, toughness, permeability, and thermal properties. One potential approach for enhancing these attributes involves the integration of nano-reinforcement. The utilisation of nanocellulose derived from biomass has garnered significant interest in recent times owing to its renewable nature, ability to biodegrade, impressive mechanical strength, low density, and considerable economic worth. In this study, we present a comprehensive overview of the most up-to-date methods for synthesising nanocellulose and its use as a filler material in the manufacture of PLA nanocomposites for food packaging. In addition, this study examines the emerging challenges and potential advantages associated with the utilization of PLA biocomposites incorporated with nanocellulose in the food packaging sector. [ABSTRACT FROM AUTHOR]

The study was to improve the heat resistance of polylactic acid (PLA) through blending modification. Ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) and poly(butylene succinate) (PBS) and talc powder (talc) were added to PLA matric to prepare PLA/E-MA-GMA/PBS/talc blends. The effects of PLA/E-MA GMA/PBS/talc content on the mechanical properties, flowability, rheological properties, heat resistance of the blends were studied. The results show that with the change of PLA/EMAGMA/PBS/ talc blend system, the tensile strength of the blends gradually decreases, while the toughness and impact strength gradually increase, indicating the existence of partial toughening and compatibility between the blend materials. Theheat deflection temperature of the untreated blends remains relatively stable at around 55 °C, while the heat deflection temperature of the crystallized blends is generally higher than 90 °C. [ABSTRACT FROM AUTHOR]

After altering ground tire rubber(GTR) with formic acid and hydrogen peroxide, the epoxidation product (EGTR) was produced. The poly(lactic acid) (PLA)/EGTR blends were then made using the melt blending method, and their micro-morphology, crystalline behavior, and mechanical properties were all carefully examined. The results showed that the carbon-carbon double bond on the GTR molecular chain was successfully oxidized to an epoxy group by formic acid and hydrogen peroxide. The EGTR particles were evenly distributed throughout the PLA matrix, demonstrating good compatibility between the two phases. Furthermore, low levels of EGTR promote PLA crystallization, while high levels of EGTR inhibit PLA crystallization. The PLA/5% EGTR blends had the highest crystallinity of 11.1%, which was 4.8 times higher than that of pure PLA. The blends tensile strength declined as the EGTR content increased, while the impact strength and elongation at break showed a tendency of first increasing and then decreasing. When 10% EGTR was added, the blends had the maximum elongation at break and impact strength, with good toughening effect and tensile strength, showing the best overall mechanical properties. The study provides a basis and technical foundation for modifying PLA with GTR as a toughening material and promotes the recycling of waste rubber. [ABSTRACT FROM AUTHOR]

The 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. [ABSTRACT FROM AUTHOR]

Appropriate protection and guiding are crucial during peripheral nerves repair. New generation nerve guidance conduits (NGCs) should not only provide mechanical support for the damaged nerve but also support healing processes. One of the most promising tissue regeneration applications is fibrous biomaterials since they are characterized by high porosity, flexibility, and strength. Additionally, they enable cell adhesion and proliferation. In this study, novel fibrous nanocomposites were obtained by applying the electrospinning technique, using polylactic acid (PLA) as a polymeric matrix which was further modified with metallic nanoparticles coated with conductive polymers. Such an approach resulted in the obtainment of biomaterials with a potential ability to conduct nerve impulses. The chemical structure of the obtained composites, as well as the morphology of ready products and separate nanocomponents, were investigated using Fourier-transform infrared spectroscopy (FTIR), transmission electron microscope (TEM) and scanning electron microscope (SEM) techniques. Furthermore, conductive and swelling properties in various media were determined. Finally, biomaterials were confirmed to be non-cytotoxic to L929 mouse fibroblasts and 1321N1 human glial cells. Based on the presented results, it can be concluded that nanofibrous nerve guidance conduits have all the key properties in the process of peripheral nerve regeneration and may constitute an important step in novel NGCs development.

Nanocomposites of polylactic acid (PLA) and poly(ethylene‐octene) grafted with glycidyl methacrylate (POE‐g‐GMA) were prepared using multi‐walled carbon nanotubes (MWCNT) as conductive nanofillers. The PLA/POE‐g‐GMA/MWCNT nanocomposites were processed through extrusion and injection molding for rheological, mechanical, electromagnetic, thermal, thermomechanical, and morphological characterization. The carbon nanotubes were dispersed in the PLA/POE‐g‐GMA chain, as seen by Raman spectroscopy. With higher MWCNT content, the complex viscosity (η*) and storage modulus (G') significantly increased in the nanocomposites, suggesting percolation formation. The nanocomposites melt flow index (MFI) results indicated lower fluidity, confirming the trend in η*. Electrical conductivity was optimal for PLA/POE‐g‐GMA/MWCNT (5 phr), reaching a value of 2.21 × 10−6 S/cm and providing electromagnetic shielding of 8 dB across the entire Ku band (12.2–18 GHz). The impact strength of the nanocomposites was higher than that of pure PLA and the PLA/POE‐g‐GMA blend, while the heat deflection temperature (HDT) remained stable at around 56°C. Increased MWCNT content in the nanocomposites promoted recovery of the elastic modulus, tensile strength, and Shore D hardness compared to PLA/POE‐g‐GMA blend. Overall, the results indicate that the PLA/POE‐g‐GMA/MWCNT (5 phr) nanocomposite has potential antistatic applications. [ABSTRACT FROM AUTHOR]

Global regulations are guiding society towards more sustainable material solutions. This increasing awareness of the need for environmentally friendly alternatives has led to a greater emphasis on biocomposites, which combine natural fibers with bio-based polymers. This study investigates how bleached softwood pulp fibers (BSWPF) and unbleached softwood pulp fibers (UBSWPF) affect the characteristics of poly(lactic acid) (PLA)-based biocomposites. UBSWPF is a more cost-effective option because it is manufactured with less processing steps than BSWPF. However, it is largely unexplored as a reinforcement in biopolymers. Through investigating the mechanical, thermal, and morphological aspects of the biocomposites, this study showed that UBSWP increased the modulus and impact strength of the PLA biocomposites better than BSWPF. The impact strength, modulus, and tensile strength of PLA-BSWPF and PLA-UBSWPF improved as the fiber content increased. However, a decrease in tensile strength was seen at higher percentages of UBSWPF in PLA. Despite the decrease in tensile strength at higher UBSWPF concentrations, both types of fibers improved the mechanical properties of the biocomposites, demonstrating a potential sustainable reinforcing material for PLA biocomposites.

Abstract The canola oil industry generates significant waste as canola meal (CM) which has limited scope and applications. This study demonstrates the possibility of valorization of CM as a sustainable natural filler in a biodegradable polymer composite of Poly(lactic acid) (PLA). Generally, interfacial bonding between natural fibers and the polymer matrix in the composite is weak and non-uniform. One possible solution is to derivatize natural fibre to introduce interfacial bond strength and compatibility with the PLA polymer matrix. Here, CM was succinylated in a reactive extrusion process using succinic anhydride at 30 wt% to get 14% derivatization with 0.02 g of -COOH density per g of CM. The CM or succinylated CM at 5 and 15 wt% was co-extruded with amorphous PLA to get composite fibers. CM-PLA and succinylated CM-PLA biocomposites were foamed using a mild and green microcellular foaming process, with CO2 as an impregnating agent without any addition of organic solvents. The properties of the foams were analyzed using differential scanning calorimetry (DSC), Dynamic mechanical thermal analysis (DMTA), shrinkage, and imaging. The addition of CM or succinylated CM as a natural filler did not significantly change the glass transition temperature, melting point, percent crystallization, stiffness, and thermal stability of PLA foams. This suggests succinylation (modification) of CM is not a mandatory step for improving interphase compatibility with the amorphous PLA. The new PLA-CM foams can be a good alternative in the packaging industry replacing the existing petroleum-based polymer foams. Graphical Abstract

Extensive research and practical applications have been conducted within the biomaterials domain, focusing on polylactic acid (PLA) based composite. These composites have been explored for their favorable attributes, such as excellent processability, biodegradability, and bioactivity properties, but still lack mechanical properties. In this work, PLA-based nanocomposites were prepared by incorporating hydroxyapatite (HA) and graphene oxide (GO) via melt mixing (extruder). Filaments were obtained to develop scaffolds through 3D printing, utilizing the fused deposition method (FDM). The GO was produced using Hummer’s method and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman Spectroscopy. The composites were analyzed using Fourier-transform infrared spectroscopy (FTIR), molecular weight, contact angle measurements, and thermal, mechanical, and rheological analysis. Adding only 0.05 wt% of GO to both PLA and PLA/HA resulted in enhancements in mechanical properties, particularly tensile strength, and significantly modified the surface properties of the materials studied. Specifically, formulation involving PLA/HA/GO was the only one to exhibit rheological properties compatible with the scaffold production process via FDM. These specific formulations were also investigated regarding cytotoxicity, and the presence of GO induces good cytocompatibility in mouse osteoblast cells (MC3T3). These results suggest that FDM technology can be used to fabricate higher-performance (mechanical and biological) scaffolds for tissue engineering.

The effect of swelling and plasticizer content of a plastic, as well as the ethanol content of the food simulant on the migration kinetics of three stabilizer-type additives from polylactic acid (PLA)-based food contact plastics has been investigated. The results proved that the parameters that affect the diffusion of substances inside the polymer matrix, i.e., swelling, plasticization, and the size of migrants, are the decisive factors in the migration from PLA to ethanolic food simulants. Both swelling and migration were negligible when ethanol 10% (v/v) was used. Contrarily, the specific migration limits of Commission Regulation (European Union, EU) No. 10/2011 were exceeded in ethanol 50% (v/v) for all investigated stabilizers. Migration was promoted by plasticization, but this effect could only be observed when the applied food simulant swelled the plastic (at least 20% (v/v) ethanol content). The dependence of the plasticizer’s migration-enhancing effect on the swelling has not been shown before. When the plasticization caused increased migration, it also led to specific migration limit exceeding within a shorter period of time. It happens even if PLA-based plastics are dedicated to the storage of hydrophilic food, which is the most common application area of these products. These results can support the improvement of both consumer safety and active packaging development.

Highlights This study aims to enhance the properties of biodegradable plastics by blending poly(lactic acid) (PLA) as well as poly(butylene succinate) (PBS) with silicon carbide (SiC). SiC content was varied from 10 to 40 phr using an internal mixer, maintaining a 90/10 wt% ratio of PLA/PBS as the matrix. The investigation covered mechanical, thermal properties, chemical structure, and composite morphology. The morphological analysis confirmed even dispersion of SiC within the PLA/PBS matrix, possibly due to improved compatibility via a silane coupling treatment. This resulted in the maximum Young's modulus and impact strength with 40 phr SiC, showing a 40% and 76% enhancement, respectively, compared to pure PLA. Concerning thermal properties, SiC addition influenced the mobility of PLA/PBS molecular chains and crystalline structure, leading to an increase in Tg with higher SiC fractions. However, ΔHm of PLA, PBS, and Xc,PLA decreased, which corresponds to reduced viscosity in the PLA/PBS blend and increased mobility with higher SiC content, as indicated by the elevated MFI value. Young's modulus increased by 40% and impact strength by 76% than pure PLA. Even SiC dispersion in PLA/PBS, possibly aided by silane coupling. SiC alters chain mobility, boosts crystalline structure, raising Tg. ΔHm and Xc,PLA reduced, suggests reduced viscosity in PLA/PBS at more SiC. Elevated MFI value shows increased chain mobility in PLA/PBS blend at more SiC. [ABSTRACT FROM AUTHOR]

A quantitative analysis of the morphology, as well as an analysis of the distribution of components and surface/interfacial properties in poly(lactic acid)(PLA) InegoTM 3251D, poly(ε-caprolactone) (PCL) Capa 6800 and nano-silica (SiO2) Aerosil®200 blends, was conducted in this research. The study aimed to improve the understanding of how PLA, PCL, and nano-SiO2 interact, resulting in the specific morphology and surface properties of the blends. Samples were produced by varying the concentration of all three components. They were analyzed using SEM, EDS mapping, water contact angle measurements, surface free energy calculation, adhesion parameter measurements, and FTIR-ATR spectroscopy. The results showed that the addition of SiO2 nanoparticles led to an increase in the contact angle of water, making the surface more hydrophobic. SEM images of the blends showed that increasing the PCL content reduced the size of spherical PCL elements in the blends. FTIR-ATR analysis showed that SiO2 nanoparticles influenced the structure ordering of PLA in the blend with equal portions of PLA and PCL. In the samples with a higher PCL content, the spherical elements present in the samples with a higher PLA/PCL ratio have been reduced, indicating better interactions at the interface between PLA, PCL, and SiO2. SEM-EDS mapping of the PLA/PCL 100/0 blend surfaces revealed the presence of SiO2 clusters and the silicon (Si) concentration reaching up to ten times higher than the nominal concentration of SiO2. However, with the addition of 3% SiO2 to the blend containing PCL, the structure became more granular. Specifically, Si protrusions in the sample PLA/PCL 90/10 with 3% SiO2 displayed 29.25% of Si, and the sample PLA/PCL 70/30 with 3% SiO2 displayed an average of 10.61% of Si at the protrusion locations. The results confirmed the affinity of SiO2 to be encapsulated by PCL. A better understanding of the interactions between the materials in the presented blends and the quantitative analysis of their morphology could improve the understanding of their properties and allow the optimization of their application for different purposes. [ABSTRACT FROM AUTHOR]

High-molecular-weight poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) is a flexible and biodegradable bioplastic that has promising potential in flexible food packaging but it has no antibacterial ability. Thus, in this work, the effect of zinc oxide nanoparticles (nano-ZnOs) which have antimicrobial activity on various properties of PLLA-PEG-PLLA was determined. The addition of nano-ZnOs enhanced the crystallization, tensile, UV-barrier, and antibacterial properties of PLLA-PEG-PLLA. However, the crystallization and tensile properties of nanocomposite films decreased again as the nano-ZnO increased beyond 2 wt%. The nano-ZnO was well distributed in the PLLA-PEG-PLLA matrix when the nano-ZnO content did not exceed 2 wt% and exhibited some nano-ZnO agglomerates when the nano-ZnO content was higher than 2 wt%. The thermal stability and moisture uptake of the PLLA-PEG-PLLA matrix decreased and the film's opacity increased as the nano-ZnO content increased. The PLLA-PEG-PLLA/ZnO nanocomposite films showed good antibacterial activity against bacteria such as Escherichia coli and Staphylococcus aureus. It can be concluded that nano-ZnOs can be used as a multi-functional filler of the flexible PLLA-PEG-PLLA. As a result, the addition of nano-ZnOs as a nucleating, reinforcing, UV-screening, and antibacterial agent in the flexible PLLA-PEG-PLLA matrix may provide protection for both the food and the packaging during transportation and storage. [ABSTRACT FROM AUTHOR]

The manufacturing method influences the properties of the produced components. This work investigates the influence of manufacturing methods, such as fused deposition modeling (3D printing) and injection molding, on the water absorption and mechanical and thermal properties of the specimens produced from neat bio-based poly(lactic acid) (PLA) polymer and poly(lactic acid)/wood composites. Acrylonitrile butadiene styrene (ABS) acts as the reference material due to its low water absorption and good functional properties. The printing layer thickness is one of the factors that affects the properties of a 3D-printed specimen. The investigation includes two different layer thicknesses (0.2 mm and 0.3 mm) while maintaining uniform overall thickness of the specimens across two manufacturing methods. 3D-printed specimens absorb significantly higher amounts of water than the injection-molded specimens, and the increase in the layer thickness of the 3D-printed specimens contributes to further increased water absorption. However, the swelling due to water absorption in 3D-printed specimens decreases upon increased layer thickness. The tensile, flexural, and impact properties of all of the specimens decrease after water absorption, while the properties improve upon decreasing the layer thickness. Higher porosity upon increasing the layer thickness is the predominant factor. The results from dynamic mechanical analysis and microscopy validate the outcomes. The results from this experimental study highlight the limitations of additive manufacturing. [ABSTRACT FROM AUTHOR]

The canola oil industry generates significant waste as canola meal (CM) which has limited scope and applications. This study demonstrates the possibility of valorization of CM as a sustainable natural filler in a biodegradable polymer composite of Poly(lactic acid) (PLA). Generally, interfacial bonding between natural fibers and the polymer matrix in the composite is weak and non-uniform. One possible solution is to derivatize natural fibre to introduce interfacial bond strength and compatibility with the PLA polymer matrix. Here, CM was succinylated in a reactive extrusion process using succinic anhydride at 30 wt% to get 14% derivatization with 0.02 g of -COOH density per g of CM. The CM or succinylated CM at 5 and 15 wt% was co-extruded with amorphous PLA to get composite fibers. CM-PLA and succinylated CM-PLA biocomposites were foamed using a mild and green microcellular foaming process, with CO2 as an impregnating agent without any addition of organic solvents. The properties of the foams were analyzed using differential scanning calorimetry (DSC), Dynamic mechanical thermal analysis (DMTA), shrinkage, and imaging. The addition of CM or succinylated CM as a natural filler did not significantly change the glass transition temperature, melting point, percent crystallization, stiffness, and thermal stability of PLA foams. This suggests succinylation (modification) of CM is not a mandatory step for improving interphase compatibility with the amorphous PLA. The new PLA-CM foams can be a good alternative in the packaging industry replacing the existing petroleum-based polymer foams. Highlights: Valorization of CM as a sustainable natural filler in PLA biocomposite foams Modification of CM is not mandatory for interphase compatibility with the PLA PLA-CM foams have similar appearance and properties to control PLA foams New PLA-CM foams can be a good alternative in the packaging industry [ABSTRACT FROM AUTHOR]

To use polylactic acid in demanding technical applications, sufficient long-term thermal stability is required. In this work, the thermal aging of polylactic acid (PLA) in the solid phase at 100 °C and 150 °C is investigated. PLA has only limited aging stability without the addition of stabilizers. Therefore, the degradation mechanism in thermal aging was subsequently investigated in more detail to identify a suitable stabilization strategy. Investigations using nuclear magnetic resonance spectroscopy showed that, contrary to expectations, even under thermal aging conditions, hydrolytic degradation rather than oxidative degradation is the primary degradation mechanism. This was further confirmed by the investigation of suitable stabilizers. While the addition of phenols, phosphites and thioethers as antioxidants leads only to a limited improvement in aging stability, the addition of an additive composition to provide hydrolytic stabilization results in extended durability. Efficient compositions consist of an aziridine-based hydrolysis inhibitor and a hydrotalcite co-stabilizer. At an aging temperature of 100 °C, the time until significant polymer chain degradation occurs is extended from approx. 500 h for unstabilized polylactic acid to over 2000 h for stabilized polylactic acid. [ABSTRACT FROM AUTHOR]

Being a bio-sourced and biodegradable polymer, polylactic acid (PLA) has been considered as one of the most promising substitutes for petroleum-based plastics. However, its wide application is greatly limited by its very poor ductility, which has driven PLA-toughening modifications to be a topic of increasing research interest in the past decade. Toughening enhancement is achieved often at the cost of a large sacrifice in strength, with the toughness–strength trade-off having remained as one of the main bottlenecks of PLA modification. In the present study, a bio-elastomeric material of epoxidized soybean oil (ESO) crosslinked with sebacic acid (SA) and enhanced by graphene oxide (GO) nanoparticles (NPs) was employed to toughen PLA with the purpose of simultaneously preserving strength and achieving additional functions. The even dispersion of GO NPs in ESO was aided by ultrasonication and guaranteed during the following ESO-SA crosslinking with GO participating in the carboxyl–epoxy reaction with both ESO and SA, resulting in a nanoparticle-enhanced and dynamically crosslinked elastomer (GESO) via a β-hydroxy ester. GESO was then melt-blended with PLA, with the interfacial reaction between ESO and PLA offering good compatibility. The blend morphology, and thermal and mechanical properties, etc., were evaluated and GESO was found to significantly toughen PLA while preserving its strength, with the GO loading optimized at ~0.67 wt%, which gave an elongation at break of ~274.5% and impact strength of ~10.2 kJ/m2, being 31 times and 2.5 times higher than pure PLA, respectively. Moreover, thanks to the presence of dynamic crosslinks and GO NPs, the PLA-GESO blends exhibited excellent shape memory effect and antistatic properties. [ABSTRACT FROM AUTHOR]

In this study we prepared a poly(lactic acid)/ethyl cellulose (PLA/EC) bioplastic blend film by melt pressing after solvent casting and investigated the optical, thermal, and mechanical properties in relation to the structural changes revealed by various microscopies and scattering measurements. Despite the immiscibility of PLA and EC, the blend film exhibited good optical transparency due to the close match in their refractive indices. A second run of differential scanning calorimetry during heating revealed a decrease in the glass transition temperature ( T g PLA ) and melting point ( T m PLA ) of PLA with EC although EC had the higher values. Thermomechanical analysis suggested that these decreases were due to the negative pressure generated due to the suppression of PLA shrinkage below T g EC and above T g PLA during cooling. Furthermore, ductile drawing of the blend film (70/30) at an optimal temperature of 70 °C above T g PLA resulted in a uniform whitening near 100% strain. Delamination at the interface between the PLA matrix and EC domain led to the formation of micrometer-sized oriented voids, which enhanced the refractive index difference in the phase-separated structure, thereby scattering light and achieving the uniform and oriented white blend film. [ABSTRACT FROM AUTHOR]

In this study, we developed composites with a poly(lactic acid) matrix and reinforced with basalt fiber, carbon‐based nanoparticles (carbon nanotube [CNT] and expanded graphene [GNP]), and both basalt fiber and nanoparticles (hybrid composites). The composites were produced by extrusion, and then tensile specimens were injection molded from the composites. The hybrid composites exhibited enhanced mechanical properties. The reinforcing materials increased crystallinity; this was more pronounced for hybrid composites. We experienced significant increase in the glass transition temperature, which proves the better interaction between the reinforcing and the matrix phases. Dynamic mechanical thermal analysis showed that the nanoparticles increased the storage modulus both alone and in combination with basalt fibers. Furthermore, the basalt fiber‐reinforced composites and hybrids exhibited significant modulus above the glass transition temperature. Based on scanning electron microscopy images of the fracture surfaces, we concluded that adding basalt fibers during compounding resulted in better dispersion of the nanoparticles. Highlights: Poly(lactic acid) (PLA) reinforced with basalt fiber has good strength properties.Graphene hybrid exhibits notable tensile modulus improvement in hybrids.Graphene and carbon nanotubes are crystalline nucleating agents for PLA.Enhanced nanoparticle distribution was discovered for hybrid composites.The glass transition temperature of PLA increases with reinforcement. [ABSTRACT FROM AUTHOR]

Wearable pressure sensors have attracted significant attention owing to their potential applications in health monitoring and connectivity to internet‐based apps. Polymers such as poly(vinylidene fluoride) have been used in sensors. However, being petroleum‐derived materials, they do not decompose and remain in the soil when disposed. Poly(l‐lactic acid) (PLLA) is a promising material because of its biodegradable nature and its derivation from plant‐based materials. In addition, the electrospun PLLA fiber mat contains real charges and exhibits electromechanical properties. However, the detailed charging properties of the PLLA fiber mats remain unclear. Herein, the charge distribution of these fiber mat is presented, and a charging model of the fiber mat and a numerical model of the output charges from the fiber mats with electrodes are proposed. Additionally, the retention properties of the stored charges are determined using surface potential measurements at different temperatures. In addition, a self‐power‐generating touch sensor and mask‐type sensor are developed using biodegradable materials produced from biomass. These studies contribute to the improvement in the charge properties of PLLA fiber mats and the resulting wearable biodegradable sensors. [ABSTRACT FROM AUTHOR]

This study investigated the solubility of poly(lactic acid) (PLA) in various solvents (to achieve an 8 % (w/v) polymer solution) and its impact on the morphology of electrospun PLA nanofibers. Several solvents, such as dichloromethane (DCM), chloroform (CHL), tetrahydrofuran (THF), acetone (AC), acetonitrile (ACTNR), dimethylformamide (DMF), dimethylacetamide (DMAc), ethylene glycol (ETGLY), distilled water (WATER), methanol (MEOH), formic acid (FA), and n‐hexane (NHX) were used in their pure and binary forms at several ratios (4 : 1, 2 : 1, 1 : 1, 1 : 2, 1 : 3, and 1 : 4). The study aims to explore the correlation between PLA solubility and its electrospinnability using solvents mapped from the Teas graph across different parameter zones and chemical groups. Hansen solubility parameters, including dispersion cohesion fractional solubility parameter (fd), the polar cohesion fractional solubility parameter (fp) was employed to identify the most effective solvents for PLA dissolution. Teas graph analysis highlighted a correlation between PLA solubility and solvent proximity to Hansen solubility parameters. Additionally, the solubility time varied between 1 hour and 24 hours. Polar solvents such as DCM, CHL, THF, ACTNR, and FA were able to dissolve 8 % (w/v) of PLA at different times, but only very high and effective dissolution of PLA was achieved in pure DCM and CHL whereas FA dissolved PLA in 24 hours, which resulted in the slowest solubility rate. Several structures of nanofibers, such as smooth, heterogenous, porous, fibrous, and beaded, were observed and discussed accordingly in terms of solvent type and ratio. The average nanofiber diameter ranged between 0.18 μm and 3.81 μm. Moreover, physical tests, including surface tension, density, viscosity, and conductivity, were conducted on solvent systems and CHL displayed higher viscosity, while ACTNR had the lowest viscosity and highest conductivity among pure solvents. According to the results of our study, it is possible to design further studies with the aim of deciding which solvents or binary forms should be applied to dissolve PLA within a certain time. The desired structure can be easily arranged to be used as a filter, biomimicking tissue environment, drug delivery system, or extra. [ABSTRACT FROM AUTHOR]

Nano-adjuvant vaccines could induce immune responses and enhance immunogenicity. However, the application and manufacturing of nano-adjuvant is hampered by its challenging scale-up, poor reproducibility, and low security. Therefore, the present study aimed to optimize the preparation nanoparticles (NPs) using FDA-approved biopolymer materials poly(lactic acid) (PLA) and cationic lipid didodecyl-dimethyl-ammonium bromide (DDAB), develop the scale-up process, and evaluate the stability and biosafety of it. The optimum preparation conditions of DDAB/PLA NPs on a small scale were as follows: DDAB amount of 30 mg, aqueous phase volume of 90 mL, stirring rate at 550 rpm, and solidifying time of 12 h. Under the optimum conditions, the size of the NPs was about 170 nm. In scale-up preparation experiments, the vacuum rotary evaporation of 6 h and the Tangential flow ultrafiltration (TFU) method were the optimum conditions. The results suggested that DDAB/PLA NPs exhibited a uniform particle size distribution, with an average size of 150.3 ± 10.4 nm and a narrow polydispersity index (PDI) of 0.090 ± 0.13, coupled with a high antigen loading capacity of 85.4 ± 4.0%. In addition, the DDAB/PLA NPs can be stored stably for 30 days and do not have side effects caused by residual solvents. For biosafety, the acute toxicity experiments showed good tolerance of the vaccine formulation even at a high adjuvant dose. The local irritation experiment demonstrated the reversibility of muscular irritation, and the repeated toxicity experiment revealed no significant necrosis or severe lesions in mice injected with the high-dose vaccine formulation. Overall, the DDAB/PLA NPs exhibit potential for clinical translation as a safe candidate vaccine adjuvant. [ABSTRACT FROM AUTHOR]

This research aimed to produce thermochromic composite filaments by utilizing poly(lactic acid) (PLA) as a matrix and two distinct thermochromic additives (red and yellow colors). To produce thermochromic composite filaments with ratios ranging from 10 to 40 phr, different quantities of a thermochromic masterbatch were integrated into the PLA matrix through an extrusion process. The physical, mechanical, thermal properties, and thermochromic behavior of the composite filaments were further examined. The results indicated that the thermochromic additives had minimal impact on thermal and mechanical properties, while also revealing a two‐phase separation between the smooth matrix and the spherical particle additives in the thermochromic composite filaments. Moreover, the analysis of thermochromic behavior revealed that an increase in the ratio of thermochromic masterbatches led to more pronounced coloration and clearer color changes, especially with red and yellow thermochromics indicating temperature variations below 22°C and over 65°C, respectively. The sample containing 40 phr exhibited the most intense color and noticeable color change. Furthermore, these thermochromic composite filaments can be utilized to 3D print various prototype products. Highlights: Thermochromic bioplastic composite filaments for 3D printing were successfully prepared.The thermochromic behavior analysis unveiled vivid coloration with distinct and more pronounced color changes. [ABSTRACT FROM AUTHOR]

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Biodegradable polylactic acid (PLA) has been widely used in fused deposition modeling (FDM) 3D printing. In order to improve its comprehensive properties in 3D printing, in this study, 0-40% content of polybutylene adipate terephthalate(PBAT) was selected to be blended with PLA in a twin-screw extruder; the resulting pellets were drawn into a homogeneous filament; then, PBAT/PLA samples were prepared by FDM 3D printing, and the effects of the dosage of PBAT on the mechanical properties, thermal behavior, surface wettability and melt flowability of the samples were investigated. The results showed that all the samples could be printed smoothly, and the ductility was slightly improved by the increase in the PBAT dosage; the thermal stability of PLA was enhanced by blending with PBAT, and the crystallinity increased monotonically with the increase in PBAT. After blending with PBAT, the surfaces of the samples were more hydrophilic and flowable. The important conclusion achieved in this work was that the PBAT/PLA blends, especially those containing 30%PBAT, showed great potential to replace petroleum-based plastics and are suitable for use in FDM 3D printing technologies for different applications. [ABSTRACT FROM AUTHOR]

Polymeric materials, renowned for their lightweight attributes and design adaptability, play a pivotal role in augmenting fuel efficiency and cost-effectiveness in railway vehicle development. The tailored formulation of compounds, specifically designed for additive manufacturing, holds significant promise in expanding the use of these materials. This study centers on poly(lactic acid) (PLA), a natural-based biodegradable polymeric material incorporating diverse halogen-free flame retardants (FRs). Our investigation scrutinizes the printability and fire performance of these formulations, aligning with the European railway standard EN 45545-2. The findings underscore that FR in the condensed phase, including ammonium polyphosphate (APP), expandable graphite (EG), and intumescent systems, exhibit superior fire performance. Notably, FR-inducing hydrolytic degradation, such as aluminum hydroxide (ATH) or EG, reduces polymer molecular weight, significantly impacting PLA's mechanical performance. Achieving a delicate balance between fire resistance and mechanical properties, formulations with APP as the flame retardant emerge as optimal. This research contributes to understanding the fire performance and printability of 3D-printed PLA compounds, offering vital insights for the rail industry's adoption of polymeric materials. [ABSTRACT FROM AUTHOR]

In this study, all‐green biocomposites based on poly(lactic acid) (PLA)/rice straw (RS) as an agricultural waste were prepared, and the physical, structural, and mechanical properties of these biocomposites were enhanced by alkali‐pulping of RS and chemical grafting of PLA onto the lignocellulosic fiber. The reactive compatibilizers of maleic anhydride grafted PLA (PLA‐g‐MA) were obtained through a reactive extrusion process at different processing conditions. The probable chemical reactions between the functional groups of PLA‐g‐MA with hydroxyl groups of RS pulp as well as the end groups of PLA chains can effectively improve the interfacial adhesion between the filler and matrix. However, the findings confirm the great importance of PLA‐g‐MA chemical structure in controlling the biocomposite performance. By choosing proper processing conditions for preparing PLA‐g‐MA and incorporating this compatibilizer into the PLA/treated RS biocomposite, Young modulus, tensile strength, impact strength, and tensile toughness of the PLA/RS biocomposite increased by 101%, 156%, 96%, and 327%, respectively. [ABSTRACT FROM AUTHOR]