Poly Lactic Acid Research Articles

Composite PLA films incorporated with micro/nano boron nitride for sustainable food packaging

This study aims to develop polylactic acid (PLA) based composite films with improved mechanical and barrier properties through incorporation of micro boron nitride (BN) and nano boron nitride (NBN). PLA-based films were produced using BN and NBN at varying concentrations (1 – 10% (w/w)), and characterized in terms of physical (color and thickness), mechanical (tensile strength, elongation at break, and heat seal strength), barrier (water vapor transmission rate (WVTR)), antimicrobial, and morphological properties. ΔE and whiteness of the composite PLA films increased, while transparency decreased with increased BN and NBN concentrations. Compared to the control PLA films, the tensile strength of the 1% BN or NBN added films increased by 28% or 40%, respectively. Adding BN and NBN to the PLA matrix significantly reduced the WVTR (p ≤ 0.05). Antimicrobial activity against S. aureus and E. coli was not detected. Multivariate data analysis enabled discrimination of composite PLA films based on simultaneous evaluation of their specific film characteristics. This study reveals the ideal film formulation to produce boron nitride incorporated composite PLA films with proper properties, holding potential to be used as an alternative biodegradable material for sustainable packaging of foods to replace petroleum-based materials.

Improvement of Thermo-Stability and Solvent Tolerant Property of Streptomyces sp. A3301 Lipase by Immobilization Techniques with Application in Poly (lactic acid) Polymerization by Using Biological Process

The thermo-solvent-tolerant lipase-producing actinomycete, Streptomyces sp. A3301, was utilized as a biocatalyst for poly (lactic acid) or PLA polymerization. The study aimed to optimize lipase immobilization conditions, characterize the immobilized lipase and apply it for PLA polymerization. The results showed using a sponge as the immobilizing matrix was the most effective method, achieving a maximum activity of 277 U/g of sponge. The optimal sponge size was determined to be 0.125 cm³ and pre-soaking the sponge in 0.1 M phosphate buffer at pH 7.0 for 24 h before use proved advantageous. Immobilization significantly enhanced the thermo-stability of the enzyme, with a relative activity ranging from 140 to 190 % within the temperature range of 30 to 60 °C. In contrast, the crude lipase exhibited thermo-stability only within the 30 - 50 °C range. The immobilized lipase demonstrated stability under PLA polymerization conditions, which involved a reaction mixture containing toluene and lactic acid and performed at 60 °C for 8 h. The immobilized lipase maintained its activity under this condition for 5 h, retaining a relative activity of 230 %, which was 1.2 times higher than the activity of the crude lipase. When the immobilized lipase was used in PLA polymerization, the resulting PLA product exhibited a molecular weight of 5,333 ± 0.02 Da, and the degree of polymerization was approximately 72. These findings underscore the potential of the immobilization technique to enhance lipase activity for PLA polymerization. HIGHLIGHTS PLA polymerization via a biological process is demonstrated. PLA can be polymerized by enzyme lipase produced by Streptomyces sp. A3301. Improving PLA polymerization with enzyme immobilization techniques. Sponge is the best immobilizer for PLA polymerization. PLA can be synthesized under mild conditions. GRAPHICAL ABSTRACT

A nonlinear and asymmetric monostable compliant ortho-planar spring piezoelectric vibrational energy harvester using a H-I structure

This paper proposes a compliant ortho-planar spring piezoelectric vibrational energy harvester (COPS-PVEH) using a H-I structure that exploits a nonlinearity and an asymmetric mono-stability to enhance the bandwidth of the device. The main structure is based on a double clamped beam (I-structure) coupled with four cantilever beams (H-structure) and an ortho-planar spring in the centre of the I-structure. Finite element analysis (FEA), analytical modelling, and experimentation were performed to analyse the dynamical and electrical behaviour of the harvester. The device was fabricated using polylactide (PLA). Six bimorph PZT-5H piezoelectric materials, electrically connected in parallel, were used as piezoelectric generators. The device was tested using an optimum load resistor of 90 kΩ under sinusoidal and sine sweep excitation in the gravity (vertical) direction. The pre-load (due to gravitation) causes a softening nonlinearity and an asymmetric mono-stability in the potential energy function. The results show that multiple peaks are observed in the output voltage of the harvester in the FEA, analytical modelling, and experimentation under harmonic excitation in the sub 15 Hz frequency range. Furthermore, analytical modelling and experimentation exhibit softening nonlinearity and chaotic behaviour, reaching a maximum amplitude power of 1.01 mW (at 8.3 Hz) and 1.07 mW (at 9.5 Hz) respectively under sine sweep excitation (amplitude of 0.6 g (g = 9.81 m/s2)). Experimentally, the harvester also generates an average power greater than 46 µW with a 6.8 Hz bandwidth under the same excitation. The softening nonlinearity and asymmetric mono-stability enhance the bandwidth of the harvester in the low frequency region where most broadband ambient vibrations are available in practical environments.

Simultaneous strengthening and toughening of PLA with full recyclability enabled by resin-microsphere-modified L-lactide oligomers

Various strategies have been developed to improve the brittleness of poly (lactic acid) (PLA), most of which still suffer from the toughness-strength trade-off dilemma. Herein, we prepared phenol–formaldehyde-resin microspheres (PFM) with aliphatic hydroxyl groups to initiate L-lactide polymerization and synthesized a series of PFM-modified L-lactide oligomers (PFM-OLLA) bearing different arm lengths. PFM-OLLA were then physically blended with commercial PLA in different weight ratios to prepare synchronously strengthened and toughened PFM-OLLA/PLA composites. After blending with 4 % PFM2.5-OLLA (PFM content: 2.5 %), the mechanical properties of the PFM2.5-OLLA/PLA composites were best. PFM2.5-OLLA efficiently improved the crystallization behaviors of the PFM2.5-OLLA/PLA composites, thereby significantly enhancing their strength and toughness. The maximum tensile yield strength (40.2 MPa), elongation at break (85.7 %), and impact strength (20.8 kJ/m2) of PFM2.5-OLLA/PLA composites could respectively increase by 44.2 %, 465.7 %, and 100 %, compared to the values of neat PLA. The microscopic strengthening and toughening mechanisms were attributed to the rigidity of PFM, and the heterogeneous nucleating ability as well as larger free volume of PFM2.5-OLLA, whereas the visual toughening effects were attributed to multiple crazing and shear yielding phenomena. After simple alcoholysis and filtration, the polymer components were completely converted into methyl lactate. The recycled PFM, exhibiting excellent chemical stability, were reused to synthesize a new PFM-OLLA for strengthening and toughening PLA. This study provides a sustainable strategy for the development of high-performance PLA engineering materials showing great application potentials in the automotive, electronics and housing fields.

Assessment of the carcinogenic potential of particulate matter generated from 3D printing devices in Balb/c 3T3-1-1 cells

Recently, there have been reports of sarcoma occurring in a Korean science teachers who used a 3D printer with acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) filaments for educational purposes. However, limited toxicological research data on 3D printing make it challenging to confirm a causal relationship between 3D printing and cancer. Therefore, occupational accidents involving teachers who have developed sarcoma have not been officially recognized. To address this gap, we aimed to evaluate the carcinogenic potential of particulate matter produced from ABS and PLA filaments commonly used in 3D printing. We created a generator mimicking 3D printing to generate particulate matter, which was used as an experimental material. The collected particulate matter was exposed to an in vitro system to investigate genetic damage, effects on cell transformation, and changes in carcinogenesis-related genes. Various assays, such as the comet assay, cell transformation assays, microarray analysis, and glucose consumption measurement, were employed. Cytotoxicity tests performed to determine the exposure concentration for the comet assay showed that cell viability was 83.6, 62.6, 42.0, and 10.2% for ABS at exposure concentrations of 50, 100, 200, and 400 µg/mL, respectively. PLA showed 91.7, 80.3, 65.1, and 60.8% viability at exposure concentrations of 50, 100, 200, and 400 µg/mL, respectively. Therefore, 50 µg/mL was set as the highest concentration for both ABS and PLA, and 25 and 12.5 µg/mL were set as the medium and low concentrations, respectively. The comet assay showed no changes in genetic damage caused by the particulate matter. Cytotoxicity results performed to establish exposure concentrations in the transformation assay showed that ABS showed cell viability of 88.0, 77.4, 84.7, and 85.5% at concentrations of 1.25, 2.5, 5, and 10 µg/mL, respectively, but few cells survived at concentrations above 20 µg/mL. PLA showed minimal cytotoxicity up to a concentration of 20 µg/ml. Therefore, in the cell transformation assay, a concentration of 10 µg/mL for ABS and 20 µg/mL for PLA was set as the highest exposure concentration, followed by medium and low exposure concentrations with a common ratio of 2. In cell transformation assays, only one transformed focus each was observed for both ABS and PLA particulate matter-exposed cells. The microarray assay revealed changes in gene expression, with a 41.7% change at 10 µg/mL for ABS and an 18.6% change at 20 µg/mL for PLA compared to the positive control group. Analysis of carcinogenesis-related gene expression changes on days 1, 7, and 25 of the promotion phase revealed that in cells exposed to 5 µg/mL of ABS, RBM3 gene expression increased by 3.66, 3.26, and 3.74 times, respectively, while MPP6 gene expression decreased by 0.33, 0.28, and 0.38 times, respectively, compared to the negative control group. Additionally, the measurement of glucose consumption showed that it increased in cells exposed to ABS and PLA particulate matter. Our findings suggest that the carcinogenic potential of ABS- and PLA-derived particulate matter in 3D printing cannot be completely ruled out. Therefore, further research in other test systems and analysis of additional parameters related to carcinogenesis, are deemed necessary to evaluate the carcinogenic risk of 3D printers using these materials.

Preparation and Characterization of PLA-Based Films Fabricated with Different Citrus Species Peel Powder

The present study aimed to investigate whether different citrus peel powders (orange, mandarin, and lemon) could be incorporated into polylactic acid (PLA), for the preparation and characterization of biodegradable films made of this fruit waste. In particular, films were prepared by the solvent casting method and tested in terms of physicochemical and biochemical parameters, along with mechanical properties. Furthermore, the citrus peel powders were tested for their physicochemical and biochemical properties after ethanolic extraction. The results showed that the addition of citrus powders into PLA proved to be efficient compared to the control films (PLA). The citrus peel-based films showed high antioxidant capacity (38.37%–32.54%), a considerable total phenolic content (17.2–12.58 mg GAE/L), good lightness (L*: 42.83–41.93), elastic Young’s modulus (257.95–175.38 MPa), oxygen transmission rate (976.5 mL m−2 day−1–1218 mL m−2 day−1), elongation at break (183.06%–135.95%), and tensile strength (6.15–4.56 MPa), which were affected significantly (p < 0.05) by the botanical origin of citrus peel. Concerning the citrus peel extracts, the highest values in antioxidant capacity (52.56%), total phenolic content (724.8 mg GAE/L), and titratable acidity (714.67 mg of citric acid/L) were recorded in the extract of lemon peel powders. The corresponding values for orange peel powder extracts were 39.43%, 563.8 mg GAE/L, and 576 mg of citric acid/L, while those for mandarin were 33.01%, 558.46 mg GAE/L, and 54.67 mg of citric acid/L. The application of multivariate analysis of variance and linear discriminant analysis on the mechanical properties, physicochemical, and biochemical data resulted in the differentiation of pure PLA and PLA-based films fabricated with citrus peel powder. From the above findings, it is concluded that citrus peel powders are sources of phytochemicals and can be used for the preparation of PLA-based films for potential applications in food preservation.

Microstructure-mechanical property relationships of polymer nanocomposite reinforced with lyophilized montmorillonite/carbon nanotubes hybrid particles

Abstract Introducing multi-walled carbon nanotubes (MWCNT) and montmorillonite (MMT) simultaneously into a polymer can significantly enhance its properties. Meanwhile, choosing the best technique to homogeneously disperse these nanohybrid particles in polymers, without agglomerates, is still a challenge. In this study, a hybrid MMT/MWCNT, prepared by lyophilization process, is introduced in polylactide (PLA). Morphology of the resulting nanocomposites displays synergistic relationships of the MMT/MWCNT, facilitating dispersion in PLA. The analysis of transmission electron microscopy (TEM) specific particle densities of PLA0.5hyb, PLA1.0hyb, and PLA2.0hyb shows values of 77, 64, and 35 µm⁻2, respectively. This suggests that MMT platelets are significantly more exfoliated in PLA0.5hyb compared to the other nanocomposites. It also indicates that filler aggregation increases as the MMT/MWCNT concentration increases. Compared to neat PLA, elastic modulus of nanocomposites increased by up to 46 %, demonstrating the reinforcing effect of MMT/MWCNT hybrid nanofillers. The nanocomposites exhibit viscosity, plasticity and damage phenomena, which are significantly decreased because of the MMT/MWCNT incorporation, compared to neat PLA. Furthermore, the viscoelastic properties, analyzed by dynamic thermal-mechanical analysis, record about 27 % increase in the storage modulus of the nanocomposites compared to PLA, indicating the effectiveness of the hybrid MMT/MWCNT in increasing the resistance of PLA/MMT/MWCNT nanocomposite against thermomechanical aggression.

Gradient Functionalization of Poly(lactic acid)-Based Materials with Polylysine for Spatially Controlled Cell Adhesion.

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.

4D Printing of Multifunctional and Biodegradable PLA-PBAT-Fe3O4 Nanocomposites with Supreme Mechanical and Shape Memory Properties.

4D printing magneto-responsive shape memory polymers (SMPs) using biodegradable nanocomposites can overcome their low toughness and thermal resistance, and produce smart materials that can be controlled remotely without contact. This study presented the development of 3D/4D printable nanocomposites based on poly (lactic acid) (PLA)-poly (butylene adipate-co-terephthalate) (PBAT) blends and magnetite (Fe3O4) nanoparticles. The nanocomposites are prepared by melt mixing PLA-PBAT blends with different Fe3O4 contents (10, 15, and 20 wt%) and extruded into granules for material extrusion 3D printing. The morphology, dynamic mechanical thermal analysis (DMTA), mechanical properties, and shape memory behavior of the nanocomposites are investigated. The results indicated that the Fe3O4 nanoparticles are preferentially distributed in the PBAT phases, enhancing the storage modulus, thermal stability, strength, elongation, toughness, shape fixity, and recovery of the nanocomposites. The optimal Fe3O4 loading is found to be 10 wt%, as higher loadings led to nanoparticle agglomeration and reduced performance. The nanocomposites also exhibited fast shape memory response under thermal and magnetic activation due to the presence of Fe3O4 nanoparticles. The 3D/4D printable nanocomposites demonstrated multifunctional multi-trigger shape-memory capabilities and potential applications in contactless and safe actuation.

Complete genome sequence of polylactic acid degrading Rhodopseudomonas palustris strain R1 isolated from rice field soil.

Rhodopseudomonas palustris R1 is a phototrophic, purple, non-sulfur Gram-negative bacterium first isolated from the soils of rice fields, known for its polylactic acid degradability. Here, we present the complete circular genome sequence of this bacterium, spanning 5.32 Mbp and 4,949 protein-coding sequences.

Compatibilization of Poly(lactic acid)/Poly(propylene carbonate) blends by star-shaped multi-arm polymer with low molecular weight

Compatibilizing polymer blends via a facile and efficient manner is of great significance since polymer blends are practical in industrial applications but limit severely by poor compatibility. Herein, we propose a novel compatibilization strategy that star-shaped multi-arm polymer with low molecular weight can be an excellent compatibilizer for polymer blends. As an example of the concept, a modified tannic acid (mTA) with a star-shaped multi-arm structure is fabricated to compatibilize biodegradable poly(lactic acid)/poly(propylene carbonate) (PLA/PPC) blend. Compared to traditional compatibilization methods, mTA shows higher compatibilization efficiency and lower limitation in distribution as mTA can exert compatibilization at the interface and in PLA and PPC phases. Consequently, mTA compatibilizes the PLA/PPC blend efficiently, leading to strikingly reduced size of PPC dispersed phase and optimized interface. The mechanism is revealed to stem from the reduced interfacial tension and regulated viscosity ratio. With the improved compatibility, PLA70/PPC30/mTA4 shows an elongation at break of 307.5 ± 15.4 % and a toughness of 85.2 ± 4.5 MJ/m3, which is 680 % and 800 % of that of PLA70/PPC30 respectively. We envision that this work provides a novel and facile compatibilization strategy and will promote the fabrication of high-performance polymer blends.

Effects of Grapevine Fiber and Additives on the Properties of Polylactic Acid Green Bio-Composites

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.

Improving Hydrophobicity and Water Vapor Barrier Properties in Paper Using Cellulose Nanofiber-Stabilized Cocoa Butter and PLA Emulsions

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.

Performance Analysis Associated with Experimental Verification of Innovative Poly Lactic Acid Material Developed by Fused Deposition Modeling with Quantitively Filling Strategies

Performance Analysis Associated with Experimental Verification of Innovative Poly Lactic Acid Material Developed by Fused Deposition Modeling with Quantitively Filling Strategies

Recyclable hemp hurd fibre-reinforced PLA composites for 3D printing

In this study, 3D printing filaments were produced from hemp hurd fibre-reinforced polylactide (PLA) composites. Hemp hurd microfibres were obtained through alkaline digestion followed by a bleaching treatment and were used to produce PLA-based composites with 20–40 wt% fibre content for fused deposition modelling. Tensile testing of 3D printed composites revealed a gradual increase of Young's modulus with the addition of fibres, reaching a maximum of 7.1 GPa for the 40 wt% composite - a two-fold increase to neat PLA. However, tensile strength was only improved for the 20 wt% formulation, with an increase of 8% in comparison with neat PLA. Nevertheless, the thermo-mechanical properties of the composites were significantly enhanced with the addition of fibres. In addition, physical objects were printed from the recycled filaments to assess their recyclability and printability. It was found that the recycled filaments maintained comparable mechanical properties and printability after three recycling cycles.

Pinewood biochar antistatic polymer composites: an investigation of electrical, mechanical, rheological and thermal properties

ABSTRACT This study investigates the practical applications of biochar as an innovative and sustainable conductive filler in composite materials. Utilizing the conventional melt-blending method, we prepared conductive pinewood biochar-filled poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) composites and systematically examined their electrical, mechanical, rheological and thermal properties. Our results reveal a significant enhancement of electrical and mechanical properties upon the inclusion of conductive pinewood biochar in the PLA/PBAT matrix. With the addition of 10 wt% of conductive pinewood biochar, the average surface resistivity of the composites decreased by three orders of magnitude, measuring 4.86 × 10 10 Ω / sq , which meets the antistatic requirements for polymer composites. Additionally, the average tensile strength of the biochar filler composites improved by 53% with an addition of just 1 wt% of biochar.

Metal–Polymer Joining by Additive Manufacturing: Effect of Printing Parameters and Interlocking Design

Additive manufacturing has a strong potential to produce sound metal–polymer joints using controlled polymer deposition on a metallic substrate. In this way, this study aimed to explore the morphological and mechanical properties of metal–polymer joints produced through material-extrusion-based AM using a pin-based macro-mechanical interlocking mechanism. Joints were fabricated with polylactic acid deposited onto a heated aluminium alloy substrate to form the connection. The optimisation process was focused on improving the printing parameters and pin geometries to reduce voids and enhance joint integrity. The results indicate that optimised samples exhibit superior mechanical resistance, achieving a maximum load improvement with an overall strength increase of 368.97% compared to non-optimised joints. A combined pin geometry (50% cylindrical, 50% conical) was found to be the most effective. Morphological analysis confirmed uniform polymer deposition, ensuring reliable joint performance. These findings underscore the critical role of geometric optimisation in enhancing the strength and durability of metal–polymer joints in AM applications.

Development of Fiber-Reinforced Polymer Composites for Additive Manufacturing and Multi-Material Structures in Sustainable Applications

This study investigates the mechanical properties of carbon and natural fiber-reinforced Polylactic Acid (PLA) and Polyethylene Terephthalate Glycol (PETG) composites produced via Additive Manufacturing (AM), focusing on Material Extrusion (MEX). The performance of filaments made from pre-consumer recycled PLA (rPLA) and PETG, with varying weight percentages of hemp and jute short fibers, was evaluated through tensile testing. Comparisons were made between the original filaments (PLA, carbon fiber-reinforced PLA [CF–PLA], and PETG) and their recycled versions. Multi-material compositions—neat PLA and PETG, single-graded (PLA + CF–PLA, PETG + CF–PETG), and multi-gradient (PLA + CF–PLA + PLA, PETG + CF–PETG + PETG)—were analyzed for mechanical properties. Optical microscope images of multi-material specimens were captured before and after fracture to assess failure mechanisms. The results indicate that the original CF–PETG filaments achieved a tensile strength of 50.14 MPa, which is higher than rPLA, PLA, and CF–PLA by 2%, 70%, and 6.7%, respectively. The re-manufactured PLA filaments reinforced with 7 wt% hemp fibers exhibited a tensile strength of 38.8 MPa, representing a 29% increase compared to the original PLA filaments and a 26% improvement over recycled PLA. Additionally, incorporating 7% jute fiber into PETG resulted in a tensile strength of 62.38 MPa, reflecting a 12% improvement over the original PETG filaments and a 15% increase compared to the recycled PETG filaments. Among specimens produced by AM, CF–PLA and rPLA demonstrated the highest tensile and compressive strengths. However, multi-material composites showed reduced mechanical performance compared to neat PLA and PETG, highlighting the need for improved interlayer adhesion. This study emphasizes the importance of optimizing material combinations and fiber reinforcement to enhance the mechanical properties of composites produced through AM.

PLA based biodegradable bionanocomposite filaments reinforced with nanocellulose: development and analysis of properties

The 3D printing technique has recently become more prevalent among researchers for the fabrication of nanocomposites. The low crystallinity of polylactic acid (PLA) leads to the poor mechanical and thermal properties of its 3D-printed products, which restrict their applications in many fields. To overcome the limitations of PLA, the present work aims to develop PLA-based bionanocomposite filaments with varying percentages (1, 3, and 5 wt%) of crystalline nanocellulose (CNC) through a single screw extruder. The filaments will be further utilized for the development of bionanocomposite samples to evaluate their properties. The effect of CNC reinforcement on the chemical structure of the filaments was analyzed by FTIR analysis. XRD analysis revealed that the crystallinity of the filaments was significantly improved due to the nucleating effect of CNC. The maximum crystallinity was observed in the filament containing 1 wt% CNC, which was 26% higher than the pure PLA filament. The thermal and mechanical performance of the filaments was also considerably improved after CNC reinforcement, which was confirmed by DSC-TGA and tensile test analysis. The maximum tensile strength and tensile modulus were observed to be 48.9 MPa and 1700 MPa, respectively, in the filament reinforced with 1 wt% CNC, which was 35.5% and 21.89%, respectively, higher than those of the pure PLA filament. Rheological analysis showed that the complex viscosity, storage modulus, and loss modulus of the filaments were significantly affected by the reinforcement of CNC.

Preparation and Characterization of Poly(lactic acid)-Based Poly(ethylene glycol) and Daphne Essential Oil-Loaded Smart Nanofibers for Thermal Protection.

Phase change material (PCM) stores latent heat energy, and poly(ethylene glycol) (Mw: 4000) (PEG 4000) is also a solid-liquid PCM. PEG and poly(lactic acid) (PLA) polymers are biodegradable. Essential oils are known as plant extracts with antimicrobial properties. In this study, daphne essential oil (DEO) obtained by the distillation method and PLA/PEG/DEO composite nanofibers were prepared by the electrospinning method with PLA, PEG 4000, and daphne (Laurus nobilis L.) essential oil in certain ratios (100/100/20, 100/120/20, and 100/150/20). DEO showed an antibacterial effect against Staphylococcus aureus and Escherichia coli bacteria. Thermal behaviors of the nanofibers were characterized by differential scanning calorimetry and thermogravimetric analysis. Morphological features were observed by scanning electronic microscopy (SEM), crystal behavior by X-ray diffraction analysis, and molecular structures were examined by Fourier transform infrared spectroscopy. Essential oil composition was determined by GC-MS. The thermal decomposition temperatures of the nanofibers were found between 250 and 276 °C, and the latent heat storage energies of nanofibers were 69.06, 86.76, and 96.39 J g-1 at temperatures 59.0 and 54.37 °C. High PCM added fiber was observed as 182 nm diameter with 3.264 μm diameter spheres. The produced nanofiber matrix has the potential to be used in applications such as medicine, textile, and hot food logistics.