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The performance of incompatible blends is strongly depended on their morphology and interfacial properties that can be controlled by proper compatibilizers. This research systematically investigates the interfacial properties of the binary and the ternary blends based on low-density polyethylene (LDPE), poly(lactic acid) (PLA) and maleic anhydride-grafted polyethylene (PE-g-MAH) through the melt linear viscoelastic rheological behavior of the blends and neat components analyzed by proper rheological models. Moreover, the relationship between rheology, phase morphology and mechanical properties of LDPE/PLA ternary blends with different amounts of PE-g-MAH was studied. In the rheological analyses via the additive rule indicated in the molten state, no consistent interfacial interaction between LDPE and PLA phases is made due to the presence of PE-g-MAH at the interface of the blend. However, the analyses based on the Palierne's model implied that the interfacial tension of compatibilized blends decreases. This not only resulted in improving PLA dispersed phase morphology in the compatibilized blends, but also forming in situ fibrillar composites where the compatibilizer amount was relatively high (5 and 7.5 wt.%). Unlike the molten state, because of the strong interactions between PE and PLA phases of compatibilized blends in the solid state, the tensile mechanical properties, including Young's modulus, strength and elongation-at break, could be reinforced up to 24%, 25% and 90%, respectively. Overall, findings make a profound realization of the amount depended performance of PE-g-MAH as the most common compatibilizer for PE/PLA blends, very helpful not only from scientific viewpoints but also in terms of the blend industry applications. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAP) is a well-established material in biomedical applications, especially for bone tissue regeneration, dental implants, and drug delivery systems. Recent research emphasizes enhancing the biocompatibility and osteoconductivity of orthopedic implants using HAP. This study explores the potential of combining HAP with a lipid matrix to improve the surface properties and biocompatibility of poly(lactic acid) (PLA)-based, 3D-printed, resorbable bone implants. We utilized the Langmuir–Blodgett method to deposit HAP within a dihexadecyl phosphate (DHP) matrix onto PLA substrates. This study demonstrates that DHP and HAP form stable monolayers at the air/water interface with HAP particles distributed within a homogeneous lipid matrix. The presence of HAP and the resulting changes in surface free energy (SFE) are hypothesized to enhance the biocompatibility of PLA implants. Our findings indicate that films composed of DHP + HAP 5:1 are particularly effective in altering PLA surface characteristics, potentially improving osteointegration, and reducing microbial adherence. Overall, this work highlights that surface modification of PLA with HAP and lipid matrices is the first step towards new, promising, and cost-effective strategies for developing advanced biomaterials for bone regeneration. [ABSTRACT FROM AUTHOR]

This study investigates the crystallization, microstructure, and performance of poly(lactic acid)/poly(butylene succinate) (PLA/PBS) thin films processed through blown film extrusion and biaxial orientation (BO) at various blend ratios. Succinic anhydride (SA) was used to enhance interfacial adhesion in PLA-rich blends, while blends near 50/50 formed co-continuous phases without SA. Biaxial stretching and annealing, adjusted according to the crystallization behavior of PLA and PBS, significantly influenced crystallinity, crystallite size, and molecular orientation. Biaxial stretching induced crystallization and ordered chain alignment, particularly at the cold crystallization temperature (Tcc), leading to a 70–80-fold increase in impact resistance compared to blown films. Annealing further enhanced crystallinity, especially at the Tcc of PLA, resulting in larger crystallite sizes. BO films demonstrated reduced thermal shrinkage due to improved PLA crystalline structure, whereas PLA-rich blown films showed higher shrinkage due to PLA's lower thermal resistance. The SA-miscibilized phase reduced oxygen transmission in blown films, while BO films exhibited higher permeability due to anisotropic crystal orientation. However, the annealing of BO films, especially at high temperature (Tcc of PLA), further lowered oxygen permeability by promoting the crystallization of both PLA and PBS phases. Overall, the combination of SA compatibilization, biaxial stretching, and annealing resulted in substantial improvements in mechanical strength, dimensional stability, and oxygen barrier properties, highlighting the potential of these films for packaging applications. [ABSTRACT FROM AUTHOR]

The effect of epoxidized soybean oil (ESO) on homocrystallization (HC) and stereocomplex (SC) formation behavior of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) bends was investigated utilizing differential scanning calorimetry (DSC). Isothermal crystallization was performed on ESO/PLLA/PDLA blends with varying ESO contents (0, 5, 8, and 10 wt%) and temperatures (90 °C, 120 °C, and 150 °C) for a different duration (12.5, 25, and 125 min). It was found that the ESO could effectively inhibit HC crystallization and promote SC crystallization. For the sample without ESO (ESO-0), the isothermal crystallization temperature and duration had little effect on the melting behavior, whereas sample with 5 wt% ESO (ESO-5), HC crystallization decreased while SC crystallization continued to increase with increasing duration. Additionally, at higher crystallization temperatures with constant ESO content, the melting temperature of SC crystals did not significantly change, suggesting that ESO did not degrade PLLA/PDLA blends. These findings imply that ESO modifies crystallization kinetics, suppressing HC formation and enhancing SC formation, which could benefit for specific material properties and applications. [ABSTRACT FROM AUTHOR]

This study explores the blending of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) with rice straw micro-particles (10 to 30 wt%, ≤ 250 μm) to create biocomposites using a kinetic mixer. It examines the effects of chain extender (J) and maleic anhydride (MA) as compatibilizers on material properties. Biocomposites underwent 500 h accelerated weathering to simulate environmental conditions, with analysis via Fourier-transform infrared spectroscopy (FTIR), mechanical testing, dynamic mechanical analyses (DMA), and rheological evaluations. Results indicate that the chain extender's superior performance over MA, generating 6% insoluble content compared to 1% with MA. Scanning electron microscopy (SEM) revealed reduced interfacial voids in biocomposites treated with compatibilizers. The addition of the rice straw was found to increase the tensile modulus from 2.3 to 3.4 indicating a 43% increase after 40 wt% rice particles; all the while reducing the tensile strength and ductility. Post-weathering, Joncryl® treated samples retained properties better than MA-treated ones, showing enhanced crosslinking and less decline in tensile strength (10–19% reduction for J vs. 27–30% for MA). Compatibilizers, especially the chain extender, play a crucial role in strengthening PLA and PBAT biocomposites, particularly under accelerated weathering. [ABSTRACT FROM AUTHOR]

Replacing traditional disposable, non-biodegradable plastic packaging with biodegradable plastic packaging is one of the key approaches to address the issue of "white pollution". PBAT/PLA/inorganic filler composites are widely utilized as a biodegradable material, commonly employed in the field of packaging films. However, the poor dispersion of inorganic fillers in the polymer matrix and the limited compatibility between PBAT and PLA have led to inferior mechanical properties and elevated costs. In this work, we propose a simple and effective strategy to improve the dispersion of nano-CaCO3 in a PBAT/PLA matrix through solid-state shear- milling (S3M) technology, combined with mechanochemical modification and in situ compatibilization to enhance the compatibility between PBAT and PLA. The impact of varying milling conditions on the structure and performance of the PBAT/PLA/CaCO3 composites was investigated. During the milling process, PBAT and PLA undergo partial molecular chain fragmentation, generating more active functional groups. In the presence of the chain extender ADR during melt blending, more branched PBAT-g-PLA is formed, thereby enhancing matrix compatibility. The results indicate that the choice of milling materials significantly affects the structure and properties of the composite. The film obtained by milling only PBAT and CaCO3 exhibited the best performance, with its longitudinal tensile strength and fracture elongation reaching 22 MPa and 437%, respectively. This film holds great potential for application in the field of green packaging. [ABSTRACT FROM AUTHOR]

The development of biomaterials with gradient surface modification capable of spatially controlled cell adhesion and migration is of great importance for tissue engineering and regeneration. In this study, we proposed a method for the covalent modification of PLA-based materials with a cationic polypeptide (polylysine, PLys) via a thiol-ene click reaction carried out under a light gradient. With this aim, PLA-based films were fabricated and modified with 2–aminoethyl methacrylate (AEMA) as a double bond source. The latter was introduced by reacting pre-formed and activated surface carboxyl groups with the amino group of AEMA. The success of the modification was confirmed by 1H NMR, Raman and X-ray photoelectron spectroscopy data. A further photoinduced thiol-ene click reaction in the presence of a photosensitive initiator as a radical source was further optimized using cysteine. For grafting of PLys via the thiol-ene click reaction, PLys with a terminal thiol group was synthesized by ring-opening polymerization using Cys(Acm) as an amine initiator. Deprotection of the polypeptide resulted in the formation of free thiol groups of Cys-PLys. Successful gradient grafting of Cys-PLys was evidenced by covalent staining with the fluorescent dye Cy3-NHS. In addition, PLys gradient-dependent adhesion and migration of HEK 293 cells on PLys-PLA-based surfaces was confirmed. [ABSTRACT FROM AUTHOR]

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]

Cellulose acetate (CA), synthesized by solid–liquid acetylation of low crystalline cellulose (LCCell) obtained by cold shearing in a short time under environmentally benign conditions, effectively enhanced the crystallization of poly(lactic acid) (PLA). The composite of PLA compounded with CA from LCCell exhibited higher crystallinity of PLA and flexural modulus than those from pristine PLA. CAs obtained from crystalline and recrystallized cellulose also improved the mechanical strength of PLA by compounding, but their effects were weaker than that of CA from LCCell. The factor of the effectiveness of CA obtained from LCCell is the higher miscibility with PLA originating from the sufficiently released interchain hydrogen bonds in the cellulose fibrils by cold shearing, which allows the dissolution of macroscopic aggregation of the CA chains in the composite. [ABSTRACT FROM AUTHOR]

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. Highlights: 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]

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]

Poly(L-lactic acid) (PLLA) and poly(ε-caprolactone) (PCL), two biodegradable and biocompatible polymers that are commonly used for biomedical applications, are, respectively, the result of the ring-opening polymerization of LA and ε-CL, cyclic esters, which can be produced according to several mechanisms (cationic, monomer-activated cationic, anionic, and coordination-insertion), except for L-lactide, which is polymerized only by anionic, cationic, or coordination-insertion polymerization. A series of well-defined PLLA-b-PCL block copolymers have been obtained starting from the same PLLA homopolymer, having a molar mass of 2500 g·mol−1, and being synthesized by coordination-insertion in the presence of tin octoate. PCL blocks were obtained via a cationic-activated monomer mechanism to limit transesterification reactions, and their molar masses varied from 1800 to 18,500 g·mol−1. The physicochemical properties of the copolymers were determined by 1H NMR, SEC, and DSC. Moreover, a series of nanoparticles (NPs) were prepared starting from these polyester-based copolymers by an emulsification/evaporation method. The sizes of the obtained NPs varied between 140 and 150 nm, as a function of the molar mass of the copolymers. Monomodal distribution curves with PDI values under 0.1 were obtained by Dynamic Light Scattering (DLS) and their spherical shape was confirmed by TEM. The increase in the temperature from 25 to 37 °C induced only a very slight decrease in the NP sizes. The results obtained in this preliminary study indicate that NPs have a temperature stability, allowing us to consider their use as drug-loaded nanocarriers for biomedical applications. [ABSTRACT FROM AUTHOR]

"Latxa" sheep wool is rough, and it is not used in the textile industry because the fiber diameter is high compared with other wool fibers. Nowadays, this wool is considered as disposal and, with the aim to give it value, new uses must be explored. In the current work, the "Latxa" sheep wool fiber was evaluated as poly(lactic acid) (PLA) polymer reinforcement. With the objective to optimize fiber/matrix adhesion, fibers were surface modified with peroxide. Oxidation treatment with peroxide led to chemical modifications of the wool fibers that improved the fiber/PLA adhesion, but the strength values achieved for the composites were lower compared to the neat PLA ones. The mechanical properties obtained in the current work were compared with the literature data of the PLA composites reinforced with vegetable fibers. The wool fibers showed inferior mechanical properties compared to the vegetable fiber counterparts. However, the preliminary results indicated that the incorporation of wool fibers to PLA reduced the flammability of composites. [ABSTRACT FROM AUTHOR]

In recent years, numerous researchers have incorporated plant fibers into polymers to alter the thermal and mechanical properties of materials. Grapevines, considered agricultural waste, have led to burdens for farmers and environmental challenges due to their mass production. This study aims to reduce the brittleness of polylactic acid (PLA) by adding polybutylene succinate (PBS) as a toughening agent and employing grapevine fiber (GVF) as a biomass filler. Additionally, the influence of GVF, toughening agents, compatibilizers, and lubrication agents on the tensile strength, heat deflection temperature (HDT), and impact strength of the composites was examined. The findings revealed that the addition of 10% GVF and 5% PBS increased the impact and tensile strengths of PLA from 17.47 J/m and 49.74 MPa to 29.7 J/m and 54.46 MPa, respectively. Moreover, the HDT of the composites exceeded 120 °C when the GVF content was more than 40 wt%. Additionally, the inclusion of a compatibilizer and a lubrication agent enabled the composite containing 30% GVF to achieve tensile and impact strengths of 45.30 MPa and 25.52 J/m, respectively. Consequently, these GVF/PLA green bio-composites not only improve the mechanical and thermal properties of PLA but also promote the reuse of waste grapevines. [ABSTRACT FROM AUTHOR]

This study explores the use of cellulose nanofiber (CNF)-stabilized Pickering emulsions for paper coatings, focusing on their rheological properties and effects on hydrophilicity and water vapor transmission rate (WVTR). Two types of Pickering emulsions, oil-in-water (O/W), were stabilized with 1 wt% CNF extracted from fique by-products. The oily phases of the emulsions were composed of poly(lactic acid) (PLA) and cocoa butter (CB). The physical stability, viscosity, and viscoelasticity of the emulsions were characterized. The emulsions were applied to the surfaces of Bond and Kraft papers using the rod-coating method. The coating process involved first applying a layer of the PLA emulsion followed by a layer of the CB emulsion. The coated papers were then evaluated by FE-SEM, contact angle, adhesion work, and water vapor transmission rate (WVTR). The results indicated that the coatings effectively produced a slightly hydrophobic surface on the papers, with contact angles approaching 90°. Initially, Kraft paper exhibited a WVTR value of 29.20 ± 1.13 g/m2·h, which significantly decreased to 7.06 ± 2.80 g/m2·h after coating, representing a reduction of 75.82%. Similarly, natural Bond paper showed a WVTR value of 30.56 ± 0.34 g/m2·h, which decreased to 14.37 ± 5.91 g/m2·h after coating, indicating a reduction of 47.02%. These findings demonstrate the potential of CNF-stabilized Pickering emulsions for enhancing the performance of paper coatings in terms of hydrophobicity and moisture barrier properties. The approach of this study aligns with global sustainability goals in packaging materials combining the use of PLA and CB to develop a waterborne coating to enhance the moisture barrier properties, demonstrated by a substantial reduction in water vapor transmission rates, and an improved hydrophobicity of coated papers. [ABSTRACT FROM AUTHOR]

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

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]

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To enhance the properties of poly(lactic acid) (PLA) composite films, unmodified (MWCNT) and modified multiwall carbon nanotubes (MWCNT-COOH, MWCNT-OH, and MA-g-MWCNT) were incorporated into the polymer matrix followed by the solvent casting method. The success of the modification of MWCNT with maleic anhydride (MA) was verified by absorption transmission reflectance spectroscopy (ATR). The fabricated nanocomposite films were analyzed by Fourier transform infrared (FT-IR) spectroscopy, thermal analyses, atomic force microscopy (AFM), contact angle measurements, dynamic mechanical analysis (DMA), and electrical conductivity tests. ATR spectra showed that MA was covalently grafted to the surface of the MWCNT, which was well dispersed and homogenously incorporated in the PLA matrix. The results of the thermal degradation demonstrated that the degradation value of the film increased from 328.91℃ to 347℃ with the addition of 0.5 wt% MA-g-MWCNT. Additionally, the MWCNT-OH/PLA films illustrated strongly hydrophilic nature due to the -OH groups. The surface resistance of 3 wt% of the MWCNT-COOH/PLA nanocomposite film decreased from 2.56x109 to 2.42x10³ Ω (by 106 order). Therefore, the properties of PLA were increased with the addition of functionalized MWCNTs, which can be used for different applications such as biomedical, food packaging, and electronics. [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]

Additive manufacturing is favored for its capacity to create intricate geometries and enhance component functionality more efficiently than traditional methods. Applying texture to materials is one of the processes used to add functionality to products, wherein it can improve adhesion and tribological behavior in biomedical applications while also controlling mechanical properties and providing perceptual and aesthetic improvements. In this study, custom black-white images containing vertical lines were prepared and added as textures to the design of tensile test specimens during slicing. Custom textured and untextured tensile test specimens were fabricated using the Fused Deposition Method with polylactic Acid filament to evaluate the effect of texture parameters, such as protrusion offset (0.25, 0.50, 0.75 mm), number of protrusions (3, 6) and infill pattern (rectilinear, line, concentric), on the tensile strength of the specimens. Through the analysis of tensile test results and examination of microscopic and slicing software images, it was found that texturing resulted in a reduction in ultimate tensile strength due to nozzle trajectory deviations and stress concentration. The least detrimental texturing parameters observed in this study were 0.5 mm protrusion offset and 3 protrusions with concentric and line infill patterns, resulting in a reduction in tensile strength of 2.36 and 5.79%, respectively when compared to untextured specimens.

Biomaterial-based implantable scaffolds capable of promoting physical and functional reconnection of injured spinal cord and nerves represent the latest frontier in neural tissue engineering. Here, we report the fabrication and characterization of self-standing, biocompatible and bioresorbable substrates endowed with both controlled nanotopography and electroactivity, intended for the design of transient implantable scaffolds for neural tissue engineering. In particular, we obtain conductive and nano-modulated poly(D,L-lactic acid) (PLA) and poly(lactic- co -glycolic acid) free-standing films by simply iterating a replica moulding process and coating the polymer with a thin layer of poly(3,4-ethylendioxythiophene) polystyrene sulfonate. The capability of the substrates to retain both surface patterning and electrical properties when exposed to a liquid environment has been evaluated by atomic force microscopy, electrochemical impedance spectroscopy and thermal characterizations. In particular, we show that PLA-based films maintain their surface nano-modulation for up to three weeks of exposure to a liquid environment, a time sufficient for promoting axonal anisotropic sprouting and growth during neuronal cell differentiation. In conclusion, the developed substrates represent a novel and easily-tunable platform to design bioresorbable implantable devices featuring both topographic and electrical cues. [ABSTRACT FROM AUTHOR]

At the present, the spent Pleurotus substrate (SPS), which is a lignocellulosic waste from the industrial production of mushrooms, is poorly valorized and mostly landfilled. Considering the large amount of SPS that is required to produce one kilo of mushrooms and its hazard to the environment if not properly disposed of, finding means to valorize this waste is of utmost importance. This work proposes the valorization of SPS through the extraction of cellulose nanofibers (NC-SPS), by applying several bleaching and alkaline hydrolysis treatments followed by microfluidization. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA) of NC-SPS showed that most of the lignin, hemicelluloses, and other impurities were removed after the treatments of SPS. The transmission electron microscopy analysis of NC-SPS showed the presence of nanofibers with an average width of 24.5 ± 14.9 nm, XRD indicated an increase in crystallinity from 60% for SPS to 71% for NC-SPS, while TGA showed that the onset degradation temperature increased with about 43 °C after the treatments. The new NC-SPS are similar to the nanocellulose extracted from wood and can replace it in various applications. In this work, NC-SPS were tested as modifiers for poly(lactic acid) (PLA) leading to an increase in its crystallinity, Young's modulus (of up to 57%), and storage modulus, while preserving its thermal stability and transparency. These results showed that NC-SPS acted as good reinforcing agents for PLA, and more applications are foreseen. [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.

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.

In this study, the effects of two environmentally-friendly pulping methods along with two different reactive compatibilization methods on the foamability of poly (lactic acid) (PLA)/rice straw (RS) biocomposites have been investigated. RS as an annually renewable agricultural waste is low-cost and available. Melt-compounding and melt-foaming processes were performed through a twin-screw extrusion processing. The correlations between processing and microstructure were studied. The findings show that the RS pulping with sodium bicarbonate (SB) solution leads to the lignocellulosic particles with a porous structure. The structure causes the filler/matrix mechanical engagement and improves the interfacial adhesion and rheological properties, hence forming smaller cells with the narrowest cell size distribution. In contrast, applying ultrasound waves on the RS pulp brings the particles to very smooth surfaces. These surfaces have the highest activity at the cell nucleation stage and considerably increase the foam's cell density. The reactive compatibilizers based on epoxy and maleic anhydride groups show opposing effects on the biocomposite microstructure, depending on the RS pulp type. The use of the reactive compatibilizers in the PLA/RS pulp treated with SB led to lighter foams with larger cells and higher cell densities and void fractions. Whereas the incorporation of the compatibilizers into the biocomposites containing RS pulp treated with SB and ultrasonic waves resulted in noticeably lower cell density and larger foam density. The extruded biocomposite foams with closed-cell microstructure can be used in insulation and packaging applications. [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]

Active biodegradable food packaging with antimicrobial properties is desirable for prolonging the shelf life of food products while minimising waste streams originating from the food supply chain. In the present work, a novel antifungal nanocomposite was prepared by a two-step melt-blending process using poly(lactic acid) (PLA) incorporated with 5 and 8 php of modified clay. The modified clay consisted of sodium montmorillonite (Na+-Mt) modified with silver (Ag) and benzyl dodecyl dimethylammonium chloride (BDAC) at different Ag and BDAC ratios. X-ray diffraction spectra and photomicrographs revealed the distribution of Ag particles and modified Mt layers in the PLA matrix, resulting in an intercalated structure. The antifungal activity of the PLA-based nanocomposites was tested against some foodborne pathogenic fungi Penicillium roqueforti and Fusarium moniliforme. The tensile strength and elongation at break of the nanocomposites decreased, whereas Young’s modulus increased compared with neat PLA. Incorporating 5 php of Ag20/BDAC80-Mt into the nanocomposite resulted in the highest impact strength. The water vapour permeability of the nanocomposite was comparable to that of neat PLA. Differential scanning calorimetry (DSC) showed a decrease in the Tg and Tcc of the nanocomposites, although the Tm did not change. For the PLA/Ag20/BDAC80-Mt-5 nanocomposite, the overall migration in distilled water, acetic acid (3%, w/v), and ethanol (10%, v/v) was below 10 mg/dm². Overall, the present work demonstrated the potential of the modified clay for developing antifungal active bionanocomposites for food packaging applications. [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.)

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]

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]