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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]

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]

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]

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]

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute 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.)

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]

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]

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]

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]

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]

In order to prepare low-cost and heat-resistant poly(lactic acid) (PLA) composites, in this study, bamboo fiber (BF) was added to stereo-complex crystal PLA (SC-PLA) to prepare heat-resistant composites. Poly[(phenyl isocyanate)-co-formaldehyde] [a polyaryl polymethylene isocyanate (PAPI)] was used to form cross-linked structures between SC-PLA and BF, and the effects of PAPI-cross-linked structures on the crystallization properties, mechanical properties, and heat resistance of BF/SC-PLA composites with different BF contents were systematically investigated. When 15% BF was added, the mechanical properties of the composite were significantly improved. The tensile strength increased by 85.5% compared to the unmodified composite, reaching 34.7 MPa, which was even higher than that of the SC-PLA composite (33.1 MPa). In addition, in order to explore the impact of the PAPI-modified BF/SC-PLA composite on the environment and carbon emissions, a life cycle assessment (LCA) of the composites was conducted. The addition of BF effectively reduced the impact of the composite on the environment. Notably, the emissions of CO2 decreased by approximately 11.7%, and the freshwater, marine, and land ecotoxicity were also significantly reduced. This work provided a reference for the preparation of low-cost and heat-resistant PLA composites for heat-resistant food packaging and disposable tableware and expanded the application of PLA products in the field of heat-resistant materials.

Abstract This article details the development of hybrid composites with a PLA matrix filled with coffee husks, potassium feldspar, and Bahia Beige marble. Comprehensive analysis included FTIR, hardness, contact angle, density tests, SEM for microstructural insights, and XRF for optimizing raw material compositions. Also, variance analysis was applied in all results. The study revealed that these biodegradable composites hold promise for sustainable applications. Density variations were noted due to particle compaction, and hardness slightly decreased with coffee husks, attributed to uneven component distribution. Increased hydrophilicity was observed with filler addition. SEM confirmed strong interfacial adhesion, and color consistency was maintained. Notably, coffee husks significantly enhanced the degradation rate of PLA, achieving a 100% higher rate compared to pure PLA. The presence of calcium and potassium minerals offers additional benefits for soil health. The study suggests that thermoformed, multi-layered composite capsules can be fully biodegradable, promoting environmental sustainability in coffee capsule production.

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.

In order to improve the inherent flammability of polylactic acid (PLA) and make this new biodegradable material more widely used, B-modified ZSM-5 (B/Z5) was designed as synergistic agent of intumescent flame retardant (IFR), composed of ammonium polyphosphate (APP) and pentaerythritol (PER), and introduced into PLA/IFR (PLAs) to fabricate PLAs/B/Z5 composites by melt extrusion. The flame retardancy, surface morphology, and thermal stability of the composites were investigated by TG, LOI, UL-94, CCT, and SEM. The addition of B/Z5 makes the decomposition temperature of T5% as well as T10% of PLAs reduction in nitrogen atmosphere and carbon layer form in advance. UL-94 test shows the composites reach V-0 rating. LOI value also steadily increases, and the maximum value is 36.0% with B actual loading of 5.26% (recoded as 14B/Z5) in B/Z5. The PHRR decreases by 75% from 417.77 kW/m2 for pure PLA to 103.19 kW/m2 for PLAs/14B/Z5, and THR reduces from 92.78 to 19.26 MJ/m2, which decreases by about 80% and the char yield reaches 50%. This study provides a simple and green method for the preparation of high flame-retardant PLA, which has a broad practical application prospect.

The rates of in vivo bioresorption of composite monofilaments based on polylactide (PLA) containing chitin nanofibrils of two types (pure chitin (CN) or chitin modified with poly(ethylene glycol) (CN-PEG)) or silver nanoparticles stabilized with poly(N-vinylpyrrolidone) (Poviargol) were studied. The in vivo bioresorption rate and its dependence on the degree of orientational drawing of the samples (which varied from 1 in non-oriented samples to 4 in oriented samples) were investigated up to 12 months after implantation. Bioresorption of the samples was monitored using differential scanning calorimetry, scanning electron microscopy, and mechanical tests. Using the differential scanning calorimetry (DSC) method, it was shown that there is a gradual decrease in molecular weight due to a decrease in the temperatures of phase transitions and changes in peak shapes. It has also been shown that the addition of fillers containing water-soluble polymers accelerates the bioresorption of composite sutures. A thread made from pure PLA lost half its strength by the 9th month of implantation, whereas for threads with the addition of CNPEG or Poviargol, this happened after 3.5 months. This causes leaching of water-soluble agents and changes in the supramolecular structure of the filament. This study shows the promise of using these composite threads as a suture material.

editorial

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]

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.)

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]

This research investigated and developed a laminate packaging film of poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVA) containing modified chitosan nanoparticles (MCSNPs) treated with 3-(trimethoxysilyl)propyl methacrylate silane (TMSPM) which functioned both as a reinforcement and as an antimicrobial filler. Electron beam irradiation caused crosslink between the PVA and MCSNP molecules via the free radical of carbonyl in the methacrylate group of TMSPM-grafted chitosan nanoparticles and the free radical of hydroxyl group in poly(vinyl alcohol). This improved the PVA hydrophobicity. In addition, the laminate with PVA-g-MCSNPs film irradiated with a 30 kGy electron beam showed the best performance properties due to improved interfacial adhesion between PLA and PVA-g-MCSNPs. As a consequence, the mechanical and thermal properties improved. The 30 kGy irradiated film also had better antibacterial activity against both Escherichia coli and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Essential oils have been identified as effective natural compounds to prevent bacterial infections and thus are widely proposed as bioactive agents for biomedical applications. Across the literature, various essential oils have been incorporated into electrospun fibres to produce materials with, among others, antibacterial, anti-inflammatory and antioxidant activity. However, limited research has been conducted so far on the effect of these chemical products on the physical characteristics of the resulting composite fibres for extended periods of time. Within this work, electrospun fibres of poly(lactic acid) (PLA) were loaded with the essential oil limonene, and the impact of storage conditions and duration (up to 12 weeks) on the thermal degradation, glass transition temperature and mechanical response of the fibrous mats were investigated. It was found that the concentration of the encapsulated limonene changed over time and thus the properties of the PLA–limonene fibres evolved, particularly in the first two weeks of storage (independently from storage conditions). The amount of limonene retained within the fibres, even 4 weeks after fibre generation, was effective to successfully inhibit the growth of model microorganisms Escherichia coli, Staphylococcus aureus and Bacillus subtilis. The results of this work demonstrate the importance of evaluating physical properties during the ageing of electrospun fibres encapsulating essential oils, in order to predict performance modification when the composite fibres are used as constituents of medical devices. [ABSTRACT FROM AUTHOR]

This study investigates the use of low molecular weight poly(ethylene glycol) (PEG) as a plasticizer for poly(lactic acid) (PLA). PLA/PEG blend films were prepared using the solvent casting method with varying mixing ratios. The films were analyzed using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and dynamic rheological analysis. The results indicate that the addition of PEG as a plasticizer affects the thermal and mechanical properties of the PLA/PEG blend films. The study found that the glass transition and cold crystallization temperatures decreased with increasing PEG content up to 20 wt%, while the crystallinity and crystallization rate increased. The blends with up to 20 wt% PEG were miscible, but phase separation occurred when the plasticizer content was increased to 30 wt%. Subsequently, amorphous samples of neat PLA and PLA plasticized with 10 wt% of PEG underwent annealing at various temperatures (Ta = 80–120 °C) for durations ta of 1 and 24 h. The samples were then analyzed using DSC and DMA. The addition of PEG to PLA altered the content of α′ and α crystalline forms compared to neat PLA at a given (Ta; ta) and favored the formation of a mixture of α′ and α crystals. The crystallinity achieved upon annealing increased with increasing Ta or ta and with the incorporation of PEG. [ABSTRACT FROM AUTHOR]

Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) shows promise for use in bioplastic applications due to its greater flexibility over PLLA. However, further research is needed to improve PLLA-PEG-PLLA's properties with appropriate fillers. This study employed zinc phenylphosphate (PPZn) as a multi-functional filler for PLLA-PEG-PLLA. The effects of PPZn addition on PLLA-PEG-PLLA characteristics, such as crystallization and thermal and mechanical properties, were investigated. There was good phase compatibility between the PPZn and PLLA-PEG-PLLA. The addition of PPZn improved PLLA-PEG-PLLA's crystallization properties, as evidenced by the disappearance of the cold crystallization temperature, an increase in the crystallinity, an increase in the crystallization temperature, and a decrease in the crystallization half-time. The PLLA-PEG-PLLA's thermal stability and heat resistance were enhanced by the addition of PPZn. The PPZn addition also enhanced the mechanical properties of the PLLA-PEG-PLLA, as demonstrated by the rise in ultimate tensile stress and Young's modulus. We can conclude that the PPZn has potential for use as a multi-functional filler for the PLLA-PEG-PLLA composite due to its nucleating-enhancing, thermal-stabilizing, and reinforcing ability. [ABSTRACT FROM AUTHOR]

In the current contribution, bacterial nanocellulose obtained from a by-product of Kombucha tea production and vegetal nanocellulose isolated from milled rice husks were employed as fillers of PLA-based composites prepared by intensive mixing followed by compression molding. Given the challenges associated with the incorporation of nanocelluloses—initially obtained as aqueous suspensions—into melt compounding processes, and also with achieving a proper dispersion of the hydrophilic nanofillers within PLA, three different nanofibrils incorporation strategies were studied: i.e., direct mixing of dried milled nanocelluloses and PLA; masterbatching by solvent casting of native nanocelluloses followed by melt compounding; and masterbatching by solvent casting of acetylated nanocelluloses followed by melt compounding. Composites with varying filler content (from 0.5 wt.% to 7 wt.%) were characterized in terms of morphology, optical properties, and mechanical performance. Results revealed the relative suitability of each strategy employed to promote nanocelluloses dispersion within the PLA matrix. PLA/nanocellulose masterbatches prepared by solvent casting proved to be particularly useful for feeding the nanocelluloses into the processing equipment in a dry state with limited hornification. Acetylation also contributed to a better dispersion of both nanocelluloses within the PLA matrix, although no clear positive impact on the mechanical properties of the films was observed. Finally, filler loading played an important role in the films' properties by increasing their stiffness while reducing their translucency. [ABSTRACT FROM AUTHOR]

The development of high-performance filtration materials is essential for the effective removal of airborne particles, and metal–organic frameworks (MOFs) anchored to organic polymer matrices are considered to be one of the most promising porous adsorbents for air pollutants. Nowadays, most air filters are generally based on synthetic fiber polymers derived from petroleum residues and have limited functionality, so the use of MOFs in combination with nanofiber air filters has received a lot of attention. Here, a conjugated electrostatic spinning method is demonstrated for the one-step preparation of poly(lactic acid) (PLA) nanofibrous membranes with a bimodal diameter distribution and the anchoring of Zeolitic Imidazolate Framework-8 (ZIF-8) by the introduction of TiO2 and in situ generation to construct favorable multiscale fibers and rough structures. The prepared PLA/TZ maintained a good PM2.5 capture efficiency of 99.97%, a filtration efficiency of 96.43% for PM0.3, and a pressure drop of 96.0 Pa, with the highest quality factor being 0.08449 Pa−1. Additionally, ZIF-8 was uniformly generated on the surface of PLA and TiO2 nanofibers, obtaining a roughened structure and a larger specific surface area. An enhanced filtration retention effect and electrostatic interactions, as well as active free radicals, can be generated for the deep inactivation of bacteria. Compared with the unmodified membrane, PLA/TZ prepared antibacterial characteristics induced by photocatalysis and Zn2+ release, with excellent bactericidal effects against S. aureus and E. coli. Overall, this work may provide a promising approach for the development of efficient biomass-based filtration materials with antimicrobial properties. [ABSTRACT FROM AUTHOR]

The design and synthesis of catalysts loaded with active components has attracted considerable attention in current research owing to their exceptional catalytic performance. In this study, the focus was on the utilization of tin‐loaded ZA molecular sieves, possessing remarkable adsorption properties, alongside the catalytic activity of tin. These catalysts were successfully prepared and employed for the synthesis of poly(lactic acid) (PLA) from lactic acid derived from non‐food biomass. By modifying the treatment of ZA molecular sieves, the properties of tin‐loaded ZA molecular sieves were adjusted. The resulting catalysts exhibited a high tin capacity ranging from 2.29% to 2.81% and featured abundant mesoporous structures, providing a surface area of up to 341.2 m2 g−1. Regarding the preparation of PLA, our findings demonstrated that ZA‐III‐Sn2+ as a catalyst yielded PLA with a higher weight‐average molecular weight (Mw) up to 2.57 × 104 g mol−1 and a higher yield of 65.3% compared to other catalysts. Moreover, the most optimal catalytic effect was achieved by adding the catalyst in three separate stages. Moreover, the amount of catalyst, reaction temperature and reaction time were found to influence both the molecular weight and yield of PLA. This study not only provides a valuable strategy for the preparation of loaded catalysts for PLA production but also offers new insights into the overall preparation process of PLA. © 2023 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Traditional polyethylene (PE) agricultural mulching film is difficult to degrade, which is harmful to the environment and irreversible. Poly(lactic acid) (PLA) and poly(adipic acid-butylene terephthalate) (PBAT) can be blended to prepare high strength and high flexibility degradable composites, which can effectively improve environmental pollution when used as agricultural mulching film. In this paper, the preparation technology of PLA/PBAT mulching film was summarized, and the modification of materials by inorganic fillers and organic fillers was summarized. Finally, the application and development prospect of PLA/PBAT mulching film in current agricultural production were introduced. The research shows that the preparation technology of PLA/PBAT mulching film has entered a new development stage from excellent to excellent. The addition of organic fillers or inorganic fillers can reduce the cost of PLA/PBAT mulching film, improve the compatibility of materials, and enhance many key indexes such as mechanical properties, crystallization properties and barrier properties. In practical application, PLA/PBAT plastic film can promote crop growth and increase crop yield, but its uncontrollable degradation cycle affects its development. In the future, PLA/PBAT degradable plastic film with adjustable degradation cycle can be developed according to different crop growth factors. [ABSTRACT FROM AUTHOR]

In order to reduce the environmental hazard of waste oil water, the composite nanofibrous membranes were fabricated by electrospinning technique. The membranes were prepared by blending poly(lactic acid)/reduced graphene oxide (PLA/rGO) and hydroxyl-capped polydimethylsiloxane (HTPDMS) in varying ratios. The nanofibrous membranes were subjected to characterization by a scanning electron microscopy, an infrared spectroscopy, and a contact angle instrument to assess their micro-morphology, surface composition, and hydrophobicity. The results show that the addition of HTPDMS into PLA/rGO results in the formation of membranes consisting of nano-scaled fibres with HTPDMS. The hydrophobicity of PLA/rGO membrane is greatly improved by the addition of HTPDMS. The separation of oil-water mixtures has high oil fluxes, the fluxes are higher than 18 400 L/(m²µh), and the separation efficiency is greater than 98.2%. After 10 cycles of separation, the separation efficiency of fiber membrane can still reach more than 97%, with good cycle stability. PLA/rGO/HTPDMS fiber membrane has a broad application prospect in oily wastewater treatment. [ABSTRACT FROM AUTHOR]

Human bone is a composite material of hydroxyapatite (HA) and collagen. HA (Ca10(PO4)6(OH)2) is a biomaterial with the calcium to phosphorus ratio being similar to the natural bone composition. In this study, composite materials were prepared by using poly(lactic acid) (PLA) as a polymer matrix, maleic anhydride (MAH) as a compatibilizer, and natural HA extracted from cow bone (BHA) as a suitable mechanical support filler with positive surface properties. Composites with varying HA (10-30 wt. %), PLA, and with or without MAH (0.5-8 wt. %) were prepared by a thermal decomposition method at 900 °C. In comparison to commercial HA (CHA), the effect of the PLA and MAH contribution on morphological, thermal, and mechanical properties of BHA were analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile strength measurements. As per the results, the HA30/PLA/4MAH composite with 30 wt. % HA, 66 wt. % PLA and 4 wt. % MAH offer the maximum mean tensile strength of 307.71 MPa. The overall results confirm the contribution of MAH compatibilizer in HA/PLA/MAH composite materials for bone tissue engineering from a mechanical point of view. [ABSTRACT FROM AUTHOR]

Biopolymeric nanoparticles (NPs) have gained significant attention in several areas as an alternative to synthetic polymeric NPs due to growing environmental and immunological concerns. Among the most promising biopolymers is poly(lactic acid) (PLA), with a reported high degree of biocompatibility and biodegradability. In this work, PLA NPs were synthesized according to a controlled gelation process using a combination of single-emulsion and nanoprecipitation methods. This study evaluated the influence of several experimental parameters for accurate control of the PLA NPs' size distribution and aggregation. Tip sonication (as the stirring method), a PLA concentration of 10 mg/mL, a PVA concentration of 2.5 mg/mL, and low-molecular-weight PLA (Mw = 5000) were established as the best experimental conditions to obtain monodisperse PLA NPs. After gelification process optimization, flutamide (FLU) was used as a model drug to evaluate the encapsulation capability of the PLA NPs. The results showed an encapsulation efficiency of 44% for this cytostatic compound. Furthermore, preliminary cell viability tests showed that the FLU@PLA NPs allowed cell viabilities above 90% up to a concentration of 20 mg/L. The comprehensive findings showcase that the PLA NPs fabricated using this straightforward gelification method hold promise for encapsulating cytostatic compounds, offering a novel avenue for precise drug delivery in cancer therapy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The effect of the addition of cellulose acetate propionate (CAP) on the rheological properties of poly(lactic acid) (PLA) was studied. Although the blends of CAP and PLA had phase-separated structures, a small amount of CAP did dissolve in the PLA. Therefore, the oscillatory shear moduli in the low-frequency region were greatly increased by the addition of CAP. Neat CAP exhibited marked strain hardening in transient elongational viscosity. This was attributed to the presence of CAP crystals at the processing temperature. The CAP chains that dissolved in the PLA also provided strain hardening in elongational viscosity for the blends, demonstrating that CAP, as a biomass-based plastic, is a good processing modifier for PLA. [ABSTRACT FROM AUTHOR]

Biodegradable 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. [ABSTRACT FROM AUTHOR]

The use of wheat middlings (WM) and rice husks (RH) as biofillers for mixing with poly(lactic acid) (PLA) matrix to produce new 3D-printable biocomposites was assessed. Filaments containing 10 and 20 wt.% agro-waste-derived biofillers were manufactured and, for the sake of comparison, filaments of neat PLA were also produced. The obtained filaments were characterized via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), showing potential for further application in additive manufacturing processing. Three-dimensionally printed specimens were thus produced and characterized via: DSC, also evaluating the specific heat capacity (CP) of specific 3D-printed specimens; dynamic mechanical analysis (DMA), also applied for determining the coefficient of linear thermal expansion (CLTE) measured on 3D-printed specimens in two different directions (X and Y); and tensile tests. The latter testing campaign was carried out along three printing directions (X, Y, and Z axes) to test the intrinsic biocomposite features (X-printed samples) as well as interbead and interlayer adhesion (Y- and Z-printed specimens, respectively). All samples demonstrated acceptable properties. The inclusion of a cost-free natural material leads to a strong reduction of the whole material cost. Implementing this new class of composite material to an additive manufacturing technique can significantly reduce the environmental impact of 3D-printed products. [ABSTRACT FROM AUTHOR]

The brittle behavior of poly(lactic acid) (PLA) and PLA composites with inorganic filler limits their applications; the addition of a toughening agent, such as a rubbery phase, was selected to transform the brittle to ductile behavior for versatility in various applications. This work aims to study the properties of PLA and PLA composite with filled nanosized hydroxyapatite (nHA) after adding modified natural rubber (MoNR), which acts as a toughening agent. MoNR refers to poly(acrylic acid-co-acrylamide)-grafted deproteinized natural rubber. nHA was prepared from fish scales. Its characteristics were investigated and was confirmed to be comparable to those of commercial grade. PLA-MoNR at various MoNR contents and PLA/nHA composites with/without MoNR were prepared by melt mixing. Their morphology, mechanical, and thermal properties were observed and investigated. Samples with MoNR added showed the dispersion of spherical particles, indicating incompatibility. However, the mechanical properties of PLA-MoNR, which had MoNR added at 10 phr, showed toughening behavior (increased impact strength by more than two times compared to that of neat PLA). The PLA/nHA composite with MoNR showed the same result. The addition of MoNR in the composite increased its impact strength by 1.27 times compared to the composite without MoNR. MoNR can be a stress concentrator, resulting in toughened PLA and PLA/nHA composite. [ABSTRACT FROM AUTHOR]

In the last decade, among the emerging technologies in the area of bioplastics, additive manufacturing (AM), commonly referred to as 3D printing, stands out. This technology has gained great interest in the development of new products, mainly due to its capability to easily produce customized and low-cost plastic products. This work aims to evaluate the effect of supercritical foaming of 3D-printed parts based on a commercial PLA matrix loaded with calcium carbonate, for single-use sustainable food contact materials. 3D-printed PLA/CaCO3 parts were obtained by 3D printing with a 20% and 80% infill, and two infill patterns, rectilinear and triangular, were set for each of the infill percentages selected. Supercritical fluid foaming of PLA/CaCO3 composite printed parts was performed using a pressure of 25 MPa, a temperature of 130 °C for 23 min, with a fast depressurization rate (1 s). Closed-cell foams were achieved and the presence of CaCO3 did not influence the surface of the foams or the cell walls, and no agglomerations were observed. Foam samples with 80% infill showed subtle temperature fluctuations, and thermogravimetric analysis showed that samples were thermally stable up to ~300 °C, while the maximum degradation temperature was around 365 °C. Finally, tensile test analysis showed that for lower infill contents, the foams showed lower mechanical performance, while the 80% infill and triangular pattern produced foams with good mechanical performance. These results emphasize the interest in using the supercritical CO2 process to easily produce foams from 3D-printed parts. These materials represent a sustainable alternative for replacing non-biodegradable materials such as Expanded Polystyrene, and they are a promising option for use in many industrial applications, such as contact materials. [ABSTRACT FROM AUTHOR]