Pure Polylactic Acid Research Articles

Development and characterization of MAO/PLA-nHA nanocomposite coatings on pure zinc for orthopedic applications

Zinc (Zn)-based medical alloys are considered to be a biodegradable material with great potential. Hydroxyapatite (HA) can improve the osteogenic properties of Zn alloys, but its adhesion strength needs improvement. In this study, a micro-arc oxidation (MAO) interlayer and polylactic acid (PLA) composite layers containing different contents of nano-HA (nHA) were successively prepared on the pure Zn surface by MAO and sol–gel impregnation methods. The adhesion results showed that PLA could enhance the adhesion of HA on the Zn surface, where the adhesion of the Zn/MAO/PLA-nHA (7:3) composite coating was close to that of the pure PLA layer. In addition, the degradation rate of the implant could be controlled by varying the content of nHA in the composite coating while significantly improving its bioactivity. Finally, the addition of nHA increased the roughness of the surface of the composite coating, which was favorable for cell adhesion and proliferation. The highest adhesion density of MC3T3-E1 osteoblasts was exhibited on the Zn/MAO/PLA-nHA (7:3) composite coating. The Zn/MAO/PLA-nHA (7:3) composite coatings showed good adhesion, wettability, corrosion resistance, and excellent cytocompatibility. Thus, this study provides a reasonable design guide for the modification of degradable Zn alloy surfaces in bone tissue engineering biomaterials.

Non-Woven Fibrous Polylactic Acid/Hydroxyapatite Nanocomposites Obtained via Solution Blow Spinning: Morphology, Thermal and Mechanical Behavior.

Polylactic acid (PLA) is widely used in tissue engineering and other biomedical applications. PLA can be modified with appropriate biocompatible ceramic materials since this would allow tailoring the mechanical properties of the tissues to be engineered. In this study, PLA-based non-woven fibrillar nanocomposites containing nanoparticles of hydroxyapatite (HA), a bioceramic commonly used in bone tissue engineering, were prepared via solution blow spinning (SBS). The compositions of the final materials were selected to study the influence of HA concentration on the structure, morphology, and thermal and mechanical properties. The resulting materials were highly porous and mainly constituted fibers. FTIR analysis did not reveal any specific interactions. The diameters of the fibers varied very little with the composition. For example, slightly thinner fibers were obtained for pure PLA and PLA + 10% HA, with fiber diameters of less than 400 nm, while the thicker fibers were found for PLA + 1% HA, with average diameters of 427 ± 170 nm. The crystallinity and stiffness of the PLA/HA composite increased with the HA content. Further, composites containing PLA fibers with slightly larger diameters were more ductile. Thus, with an appropriate balance between factors, such as the diameter of the solution-blow-spun PLA fibers, HA particle content, and degree of crystallinity, PLA/HA composites may be effectively used in tissue engineering applications.

Evaluation of stress-controlled high-cycle fatigue characteristics in PLA-wood fused deposition modeling 3D-printed parts under bending loads.

PLA (Poly-lactic acid)-wood provides more biodegradability through natural fibers, a significant advantage of pure PLA. Nevertheless, these bio-composites may have inferior mechanical properties compared to non-degradable polymer composites, considering the lower strength of natural particles compared to synthetic fibers. This research examines the fatigue behavior of additive-manufactured biopolymer PLA-wood and assesses its comparability with pure PLA. Therefore, solid fatigue test samples were printed using the FDM (fused deposition modeling) method. Afterward, fully reversed rotary bending fatigue experiments were performed at 4 different stress levels (7.5 to 15 MPa) to extract the S-N curve of PLA-wood. Moreover, the fatigue fracture surfaces of the PLA-wood were investigated and compared at the highest and lowest stress levels using an FE-SEM (Field Emission Scanning Electron Microscopy), indicating more ductile fracture marks at higher stress levels. The fatigue lifetime of the PLA-wood decreased by 87.48% at the highest stress level (15 MPa), rather than the result at the lowest stress level (7.5 MPa). Additionally, the results demonstrated that the fatigue characteristics of the printed pure PLA and PLA-wood were comparable, suggesting that the 3D-printed PLA-wood with the used printing parameters can be an alternative choice.

Copolyester toughened poly(lactic acid) biodegradable material prepared by in situ formation of polyethylene glycol and citric acid.

Polylactic acid (PLA) is a high-modulus, high-strength bio-based thermoplastic polyester with good biodegradability, which is currently a promising environmentally friendly material. However, its inherent brittleness has hindered its widespread use. In this study, we reported a simple and non-toxic strategy for toughening PLA, using biodegradable materials such as polyethylene glycol (PEG) and citric acid (CA) as precursors. Through reactive melt blending with PLA, PEG and CA form PEGCA copolyesters in situ during blending. At the same time, CA can react with PLA and PEG, forming a copolyester structure at the interface of the two phases, improving the interfacial compatibility between PEG and PEGCA with PLA. Fourier transform infrared spectroscopy confirms this. Experimental results show that when the content of PEG/CA reaches 15% (PLA/PEG/CA-15%) in the blends, the impact strength of the blend was 4.47 kJ m-2, and the maximum elongation at break was as high as 360.1%, which were about 2 and 44 times higher than those of pure PLA, respectively. Moreover, the tensile strength was still maintained at the level of 70%. This work can expand the application of PLA in food packaging and medical supplies.

Hollow porous PLA/PBAT composite microfibers with enhanced toughness and prolonged drug release for wound healing

An appropriate wound dressing is necessary to enhance the recovery of wounds and the restoration of tissue after the skin gets injured. In this study, a hollow porous microfiber (HPMF) scaffold composed of a combination of polylactic acid (PLA)/polybutylene adipate/butylene terephthalate (PBAT)/polyvinyl alcohol (PVA) was developed using coaxial electrospinning for wound healing. The porous structure of PLA/PBAT HPMFs was formed by dissolving PVA in water. The results showed that when maintaining a PLA: PBAT weight ratio of 7:3, high-quality porous PLA/PBAT composites were achieved, leading to a 36.25% increase in toughness and a 4.9% increase in biodegradability compared to pure PLA. Furthermore, in vivo wound healing assays suggest that composites successfully loaded can effectively promote wound healing on the 13th day. Therefore, this work underscores the significant potential of PLA/PBAT HPMF dressing for wound repair.

Influence of bio-coupling agent on interfacial interlocking compatibility and toughness of ultrafine bamboo charcoal/polylactic acid composite film

Applications for polylactic acid (PLA) are significantly impacted by its poor mechanical properties and lack of thermal stability. The goal of this work is to bridge the gap of poor compatibility among the components and enhance their interface interlocking capability to improve the toughness and thermal stability. Ultrafine bamboo charcoal (UFBC) was treated through deep eutectic solvent (DES) method to deposit sodium lignosulfonate (LS) on its surface. LS was used with PLA as a bio-coupling agent to create an eco-friendly PLA composite film with a wide range of characteristics. Benefiting from the penetration of PLA to the internal pores in UFBC, the resultant L-UFBC/PLA film has a good mechanical interlocking structure. Ls can increase the compatibility and strengthen the interface interlocking capability through DES method, which greatly improves the mechanical properties of the system. In comparison to pure PLA one, the elongation at break was 136.24 % greater, and the crystallinity (Xc) increased from 1.09 % to 3.33 %. Furthermore, the thermal stability of the system was also improved, and the residual at 600 °C rose by 4.83 %. These characteristics offer the prepared L-UFBC/PLA film a wide range of potential applications in the packaging, medical, agricultural, and other sectors.

Brewing sustainability and strength: Biocomposite development through tea waste incorporation in polylactic acid

This study aims to enhance the mechanical properties of polylactic acid by incorporating black tea waste as an economical and sustainable additive capable of being recycled. The black tea waste, after the hot water color removal process, is milled to a fine and uniform powder size. The combination of these particles with polylactic acid is carried out using a twin-screw extruder. Specimens of pure polylactic acid and biocomposites containing 3 and 5 wt% black tea waste are manufactured using a hot press machine at a temperature of 200 °C. The filaments are also successfully extruded for three-dimensional printing purposes. Scanning electron microscopy images reveal that in the polylactic acid–3% tea biocomposite, the tea particles are appropriately dispersed within the polylactic acid matrix. The tensile test results indicate that biocomposite polylactic acid-3% tea has the highest mechanical properties, with a tensile strength of 67 MPa, demonstrating a 34% increase compared to polylactic acid. Furthermore, the biocomposite of polylactic acid–3% tea waste exhibits the best performance with a fracture energy of 2.5 kJ/m2 in the impact test. Hence, polylactic acid–3% tea biocomposite can be recommended as a suitable sustainable substitute. Finally, numerical simulations are performed on biocomposites containing double keyhole notches. This analysis is conducted to observe the behavior of biocomposite models with double keyhole notch under mixed-mode loading. The critical fracture load of the models is calculated using the strain energy density criterion. It is observed that an increase in the notch inclination angle and notch radius leads to a decrease in the fracture load in the models.

Degradation behaviors and crystallization of rapidly degradable polylactic acid prepared by melting through coordination complexation reaction

The nondegradability of petroleum-based non-degradable plastics leads to accumulation of a large amount of waste. The waste disposal method seriously pollutes the environment. The development and application of biodegradable polymers are considered as a green solution to the problem of environmental pollution. However, as the market for degradable materials continues to expand, the rate of production largely exceeds the rate of natural degradation, and the waste accumulation problem cannot be effectively addressed. In this study, PLA-modified materials were prepared by a melt blending method with polylactic acid (PLA) as a matrix material and stannous octoate (Sn(Oct)2) as an accelerator to increase the degradation rate of PLA. The Sn atom in Sn(Oct)2 complexed with the ester group of the PLA molecular chain, leading to destruction of the PLA molecular chain. When the content of the accelerator reached 2 phr, the degradation rate of the modified samples in an alkali solution was more than two times higher than that of the pure PLA, and the biodegradation rate was increased by 73.97% compared to the pure PLA. In addition, the crystallization behavior of PLA can be regulated by Sn(Oct)2. The mechanisms of the acceleration of the degradation and effect on the crystallization behavior were investigated.

In vitro degradation analysis and mechanical characterization of PLA-CF composites prepared by fused filament fabrication technique for bio-medical applications

The objective of this research work is to study the in vitro degradation behavior of as-fabricated and annealed Poly Lactic Acid (PLA) composites reinforced with varying volume fractions of carbon fiber (CF).The composites are prepared by fused filament fabrication technique (FFF). Specimens are immersed in simulated body fluid (SBF) for 8 weeks to study the degradation behavior of the composites by examining the change in weight, change in pH and degradation in mechanical properties. The obtained results show that the addition of carbon fiber reinforcement reduces the tensile strength, flexural strength, impact strength and compressive strength of the composites. Further, CF addition enhances the tensile modulus of the composite. The mechanical properties of annealed composites are enhanced when compared to as-fabricated composites. Differential Scanning Calorimeter (DSC) is employed to study the thermal characteristics of the composites and % crystallinity of the composites. CF addition reduces the crystallinity of the composites. Fractographs of the tensile fractured specimens are studied using a scanning electron microscope (SEM). The addition of the carbon fiber reinforcement is found to accelerate the degradation behavior of the composites. There is significant change in weight and pH as well as degradation in mechanical properties of PLA-CF composites immersed in SBF than pure PLA composites. Annealed composites show better degradation resistance than as-fabricated composites. SEM is employed to study the surface morphology of the composites immersed in SBF.

Mirror assembly of spherical chitosan-based additives: Towards a circular revolution of PLA from high-value applications to soil degradation

Polylactic acid (PLA) is recognized as a promising alternative to traditional petroleum-based plastics due to its excellent biodegradability and well-balanced mechanical properties. Nevertheless, the disadvantages of PLA such as flammability in fire, susceptibility to UV light attack, and slow natural degradation rate limit its application and recovery in high-security areas. In this work, a spherical chitosan-based additive DMPC-Al with mirror-symmetric internal structure was assembled by layer-by-layer electrostatic reactions, resulting in PLA characterized excellent comprehensive performances. When 7 wt% DMPC-Al was added into PLA, the LOI value of the composite PLA/7DMPC-Al was increased to 29.6%, and UL-94 reached V-0 grade without any molten droplets. The peak heat release rate and total heat release rate were reduced by 13.5% and 16.2%, respectively, and the carbon layer was highly self-expanding. In addition, the UPF of PLA/7DMPC-Al was increased to 34.45 from 0.45 of pure PLA, blocking most of the UV light attacks and extending the service life of PLA. Surprisingly, DMPC-Al actually improved the impact toughness of PLA by 38.5% and facilitated PLA to work continuously when drawing large curved shapes by 3D printing. More importantly, the introduction of DMPC-Al changed the sensitivity of PLA to water and provided sufficient energy for microbial growth, thus accelerating the degradation rate of PLA in the soil under abandoned buildings. This work provides a practical and feasible strategy to achieve multifunctionality of degradable plastics.

Exfoliation and physico-chemical characterization of novel bioplasticizers from Nelumbo nucifera leaf for biofilm application

Due to the extreme threats as environmental and health issues caused by the petroleum-based leachable plasticizers, researchers among different domains are more interested in finding unique biodegradable plasticizers from natural sources. The present study used Nelumbo nucifera leaf to extract novel biopolymers as viable substitutes for chemical plasticizers. The biopolymers extraction was carried out through chemical means and its physico-chemical and morphological characterization were carried out to confirm its plastic nature. The polymers extracted possess a low glass transition temperature (77.17 °C), good thermal stability (230 °C), low density (0.94 g/cc), good surface roughness (34.154 μm), low crystallinity index (25.1%) and moderate crystallite size (16.36 nm). The presence of an organic polymer with specific chemical groups as olefinic alkenes, epoxide, imino/azo groups, and hydrophobic organic siloxane groups, signify that the material is a condensed phenolic derivative. Furthermore, bio-film was formulated using NLP and poly lactic acid (PLA) matrix to evaluate its plasticizing effect and film-forming ability. Variation in specific properties of film was noted after bio-plasticizer addition, where tensile strength (20.94 ± 1.5 MPa to 19.22 ± 1.3 MPa) and Young's modulus (1.462 ± 0.43 GPa to 1.025 ± 0.52 GPa) was found to be decreased whereas increased the percentage of elongation at break (26.30 ± 1.1% to 39.64 ± 1.6%). In addition, decreased glass transition temperature (Tg) (59.17 °C), good surface compatibility, and increased flexibility of NLP-PLA film in contrast to pure PLA film authorizes the plasticizing effect of bio-plasticizers on PLA. Since the extracted bio-plasticizers could be a suitable replacement to harmful synthetic plasticizers for lightweight packaging applications in bioplastics sector.

The flexural and compressive properties of sandwich composites with different 3D-printed core structures

In this study, different core structures are produced with polylactic acid (PLA) and carbon fiber reinforced PLA (CFR-PLA) filaments using a 3D printer with fused deposition modeling (FDM) technique. An alternative new core structure is proposed to the honeycomb and square core structures commonly used in the literature. Then, sandwich composites are produced by bonding carbon fiber-epoxy plates to the lower and upper surfaces of these core structures. The effect of carbon fiber reinforcement and core types on the mechanical properties of sandwich composites was investigated. The core structures produced with carbon fiber-reinforced PLA showed lower compressive strength but higher compressive modulus than those produced with pure PLA. Among the core structures, the designed structure showed the highest compressive strength with a value of 9.867 MPa, which is 32.18% and 54.36% higher than the honeycomb and square structure. While the flexural strength and flexural stiffness of the sandwich composites increased with carbon fiber reinforcement, the designed sandwich composite showed approximately 1.40 and 3.15 times the flexural strength of the honeycomb and square sandwich composites, respectively.

Microwave absorption and compression performance design of continuous carbon fiber reinforced 3D printing pyramidal array sandwich structure

In this study, continuous carbon fiber reinforced 3D printing technology was used to create a novel pyramidal array sandwich structure (PASS), which contains microwave absorption and enhanced compression performances. By utilizing the electromagnetic and mechanical properties of continuous carbon fiber (CF), a spoof surface plasmon polaritons (SSPPs) microwave absorbing core was formed by winding continuous carbon fiber into a pyramidal array. Simulated and experimental results demonstrated that the proposed PASS efficiently absorbs a wide band (4–18 GHz) microwaves at large incident angles (0–60°), with an average absorptivity exceeding 90 %. Additionally, compression tests revealed that present continuous carbon fiber reinforced PASS has a compressive strength of 9.60 MPa and a modulus of 123 MPa, respectively. Furthermore, it exhibits 34.3 % and 24.8 % higher energy absorption per unit volume and mass compared to the pure polylactic acid (PLA) PASS. The advantages of microwave absorption, compression, and economical manufacturing performances make it highly promising for the engineering applications.

Fabrication of novel macromolecular P–S synergistic flame retardants and its applications in biodegradable poly (lactic acid): Combustibility, anti-melt dripping behavior, crystallization, and mechanical properties

As a biodegradable material, polylactic acid (PLA) has very bright application prospects, but its high flammability and poor crystallinity limit its use in electronics, automotive components, and other applications. In this paper, a macromolecular P–S synergistic multifunctional flame retardant (PTP) was obtained by an easy one-pot approach using polyethyleneimine, thiophene-2-formaldehyde and phytic acid. The addition of PTP to PLA improved the combustion resistance, anti-melt dripping and crystallization performance. The PLA compounds attained UL-94 V-0 grade at an ultra-low load (3 wt%) of the PTP, and the limiting oxygen index improved to 28.3 % when added at 9 wt%. The effective heat combustion and the total heat release value of PLA/9PTP composite were reduced from 24.4 and 93.1 to 18.9 MJ/kg and 86.0 MJ/m2, respectively. PLA/PTP composites provided a denser and more stable char layer during combustion than PLA and emitted significantly less-flammable gaseous volatiles. Meanwhile, PTP significantly facilitated the nucleation and crystallization of PLA, and the crystallinity elevated from 2.9 % to 35.5 % while the crystallization half-time reduced to 3.3 min about 10 % of pure PLA at 110 °C when added at 3 wt%. Besides, as PTP was a macromolecular flame retardant, PLA/PTP composites still maintained superior mechanical properties with the addition of PTP. This article gave an easy and effective way to fabricate PLA compounds with excellent flammability resistance, anti-dripping, crystallization and mechanical performance, which may be helpful for extending practical applications of PLA materials.

Accelerated ageing of 3D printed water purification filters based on PLA reinforced with green nanofibers

This study investigates the ageing behavior of polylactic acid (PLA) and PLA-based biocomposites reinforced with either 2,2,6,6-tetramethylpiperidine 1-oxyl radical (TEMPO) - oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) in water. Fused deposition modeling (FDM) was used to create water filters, which underwent aging tests at various temperatures over 19 weeks. Thermomechanical results show that while the addition of TCNF and ChNF improves the mechanical performance of PLA-based filters in dry conditions, it has the opposite effect after exposure to water. The impact of prolonged water exposure on Young's modulus and toughness was more significant in biocomposites than in unmodified PLA filters. The TCNF/PLA and ChNF/PLA filters saw a substantial ∼10 °C drop in glass transition temperature (Tg) after 3 weeks, while pure PLA remained nearly unaffected for up to 7 weeks. The mechanical tests allowed to estimate the service life of the 3D printed filters using the Arrhenius model. It was shown that the TCNF/PLA and ChNF/PLA filters can be utilized at room temperature water for up to 8 and 5 months, respectively, until they lose 50 % of their initial ability to resist deformation. In the same conditions, PLA filters can serve for up to 3.5 years. In conclusion, this study highlights the importance of considering the degradation behaviour of biocomposites when developing sustainable materials for water treatment applications.

Some studies on functional behavior of novel multi-layered material for integrated structural application

Fused deposition modeling (FDM) is a prominent technique in additive manufacturing (AM), widely employed for the construction of intricate prototypes through successive layer-by-layer deposition. Among the thermoplastic matrices used, polylactic acid (PLA) stands out as an environmentally friendly and hydrophobic polymer derived from organic sources. PLA boasts properties like biocompatibility, biodegradability, and high strength, making it a favored choice in diverse industries, including medical, food packaging, and textiles. The incorporation of wood flour into the thermoplastic matrix, referred to as Wood-PLA, has demonstrated increased material strength, leading to its adoption in sectors like automobile and aircraft interiors, fencing, flooring, musical equipment, and various other consumer goods. Additionally, the introduction of multi-material, an innovative material with varying multi-phase properties across different structural regions, has found application in a wide array of industries, including biomedical, energy storage, optoelectronics, aerospace, automobile, and defense. This study aims to investigate the impact of different build orientations (0˚, 45˚, and 90˚) on the mechanical properties of Wood-PLA, pure PLA, and multi-layered material (MLM) fabricated through FDM. Finite element analysis of tensile and compressive test has performed using ABAQUS software and compared with experimental outcomes. Additionally, fracture morphology are examined to gain insights into the modes of failure during fracture. Results reveal significant variations in the mechanical properties of Wood-PLA, PLA and MLM, depending on the build orientation. Furthermore, the examination of fracture morphology provides valuable insights into the failure mechanisms in these materials. Hence this study contributes to the growing body of research on advanced materials and additive manufacturing techniques, paving the way for improved material selection and design considerations.

Poly-lactic acid self-reinforcing composites with improved toughness utilising solid-state drawn oriented tape

With the increasing white pollution problem and the enhancement of people’s awareness of environmental protection, the bio-based and biodegradable polymers have received unprecedented attention. Poly-lactic acid (PLA) is considered as one of the most potential alternatives to petroleum-based polymer materials. However, Due to its inherent brittleness and the difficulties of post-disposal and recycling caused by traditional processing methods, PLA has not been fully accepted by the market. To overcome the issues, self-reinforcing PLA composites (SRPLA) were prepared with different PLA grades as the matrix and the reinforcement respectively. High toughness SRPLA were prepared by hot pressing using PLA3052 casting films as the matrix and PLA6202 oriented tapes fabricated by solid state drawing as the reinforcement. In addition, the toughening mechanism was analyzed. Mechanical tests showed that the strength, modulus and elongation at break were increased by 124.3%, 114% and 145.2% respectively compared with pure PLA hot pressed film. Particularly, the tensile toughness of SRPLA is more than 200% that of pure PLA. The interface debonding and tape pullout were the main toughening mechanisms.

Enhancing flame retardancy of poly(lactic acid) with a novel fully biobased flame retardant synthesized from phytic acid and cytosine

AbstractIn order to reduce environmental pollution and improve material safety, biobased flame‐retardant polymers are gradually becoming a new trend. We synthesized a fully biobased flame retardant called PACY by reacting phytic acid (PA) and cytosine (CY) in water, and then mixed the flame retardant with biodegradable poly(lactic acid) (PLA) to obtain composites, characterizing the performance of the composites by microscopic morphology, thermal properties, flame‐retardant performance and so on. The test results showed that the PLA composite with 2 wt% PACY (PLA/2PACY) achieved UL‐94V‐1 and the PLA composite with 4 wt% PACY (PLA/4PACY) had a limiting oxygen index of 23.6%. Compared to pure PLA, PLA/4PACY had good flame retardancy with 12% less peak heat release and 19% less total heat release. Analysis of the flame‐retardant mechanism showed that PACY could promote the formation of a graphitized carbon layer after burning PLA, therefore enhancing the flame‐retardant properties of PLA. Through a thermal stability study, it was found that the temperature required for PACY mass loss of 5% was 275 °C and the residual weight reached 38% at 750 °C, which indicated high thermal stability and residual carbon rate. The addition of PACY also improved the thermal conductivity of PLA, with that of PLA/4PACY being 3.84 times higher than that of pure PLA. In addition, the tensile strength, flexural modulus, maximum force during impact and maximum energy received during fracture of PLA/4PACY increased by 3.3%, 8.1%, 29.2% and 17.5% respectively over pure PLA, effectively improving the mechanical properties of PLA. Overall, a fully biobased flame retardant was synthesized for improving the fire resistance of PLA degradable polymers. © 2023 Society of Industrial Chemistry.

Effect of curcumin-modified nanodiamonds on properties of eco-friendly polylactic acid composite films

Polylactic acid (PLA) has attracted much attention as a biodegradable polymer material, but its inherent brittleness limits its application. In order to improve the overall performance of PLA, thermoplastic polyurethane (TPU) was first blended with PLA to improve the toughness, and then curcumin-functionalized nanodiamond (ND-Cur) was added to the polymer matrix to improve the strength and toughness of PLA. The effects of nanoparticles on the structure, thermal and mechanical properties of polymer matrix were investigated by scanning electron microscopy, thermogravimetric analysis and tensile testing. When the addition of ND-Cur is 1.5 wt%, the mechanical properties of the composite are the best, and the elongation at break is 124.8%, which is 119.9% higher than that of PLA. At this time, the improvement of thermal stability is also the most significant, and the T5% (temperature at 5% heat loss of sample) of the film is 47.9% higher than that of pure PLA. In addition, the modification also improved the hydrophobicity of the composite film.

Thermal and Mechanical Properties of Biocomposites Based on Polylactide and Tall Wheatgrass.

Biocomposites based on polylactic acid (PLA), tall wheatgrass (TWG), and hemp (H) were made by injection molding. The article discusses the impact of the agrofiller content on the composite properties, including thermal (DSC, DMA, and TG) and mechanical characteristics (tensile modulus, tensile strength, and impact strength). Generally, the introduction of a plant filler into the polylactide matrix reduced the thermal resistance of the resulting composites. Plant fillers influenced primarily the cold crystallization process, probably due to their nucleating properties. The addition of fillers to the PLA matrix resulted in an increased storage modulus across all tested temperatures compared to pure PLA. In the case of a composite with 50% of plant fillers, it was almost 118%. The mechanical properties of the tested composites depended significantly on the amount of plant filler used. It was observed that adding 50% of plant filler to PLA led to a twofold increase in tensile modulus and a decrease in tensile strength and impact strength by an average of 23 and 70%, respectively. It was determined that composites incorporating tall wheatgrass (TWG) particles exhibited a slightly elevated tensile modulus while showcasing a marginally reduced strength and impact resistance in comparison to composites containing hemp (H) components.