Pure Polylactic Acid Research Articles

Full bio-based flame retardant towards multifunctional polylactic acid: Crystallization, flame retardant, antibacterial and enhanced mechanical properties

The preparation of flame-retardant high-performance polylactic acid (PLA) composites by adding green flame retardants have always been a challenge. In this work, an intumescent flame-retardant PCR based on phytic acid, chitosan, and resveratrol was successfully designed. Adding 4 wt% of PCR, the PLA-PCR composite was classified as UL-94 V-0 grade, with a LOI value increasing from 19.7 % (pure PLA) to 26.0 %, a peak heat release rate decreasing from 433 to 344 kW/m2. Owing to excellent compatibility of PCR, the mechanical strength and toughness of PLA-PCR composites have been improved, as reflected by a ~ 16 % increase in tensile strength, a ~ 73 % increase in impact strength and a ~ 57 % increase in toughness. In addition, PCR also presented plasticization effect on PLA, making it easier to process. This work provided a highly efficient and environmental-friendly modification approach for the development of multifunctional polymers.

A new strategy to prepare bio-based polylactic acid modifier for multi-functionality: Dopamine-grafted modified lignin

Currently, to address the performance deficiencies associated with high brittleness, inadequate thermal stability, and susceptibility to hydrolysis in polylactic acid (PLA), it is common practice to incorporate multiple or high proportions of additives. However, this approach raises concerns regarding interface compatibility, energy consumption, and environmental impact. In this context, we introduce an environmentally friendly, bio-based PLA modifier that is facile to prepare and facilitates multi-functional applications at a minimal dosage. The presence of a benzene ring structure in lignin endows the material with ultraviolet (UV) resistance, thermal stability, and hydrophobic characteristics, while the exceptional adhesion properties of polydopamine (PDA) enhance interfacial compatibility. A novel biomass polylactic acid modifier, designated as OL@PDA, has been synthesized by modifying low-molecular-weight lignin (OL) with PDA. Comparative analysis of OL@PDA/PLA composite materials reveals a 14.08 % increase in tensile strength and a 42.00 % enhancement in elongation at break relative to pure PLA. The incorporation of the lignin-derived benzene ring structure effectively transforms PLA from a hydrophilic to a hydrophobic material. Furthermore, the UV transmittance at 400 nm (T400 nm%) is recorded at 65.8 % for pure PLA, which significantly decreases to below 5 % for OL@PDA/PLA composites. The integration of OL@PDA as a modifier in PLA materials yields comprehensively performance enhancements while maintaining a low additive concentration.

Furan-based renewable elastomers as effective tougheners for PLA: Enhanced mechanical properties and water vapor barrier properties

There is a great need for versatile biomass additives sourced from renewable materials to enhance the performance of polylactic acid (PLA) composites. This study introduces a furan-based polyester elastomer called PNF-PBC that is designed to improve the mechanical and water vapor barrier characteristics of PLA. By incorporating PNF-PBC into PLA, the toughness of the PLA/PNF-PBC biocomposites was considerably enhanced through various intermolecular interactions. A 15 wt% PNF-PBC blend with PLA exhibited a 13.6-fold increase in elongation at break, while having a negligible impact on tensile strength. Furthermore, the water vapor barrier performance of PLA/PNF-PBC biocomposites was greatly boosted by a factor of 10 compared to pure PLA, making them highly suitable for food packaging materials. With its versatile properties, we anticipate that this bio-based PLA/PNF-PBC material will significantly expand the range of applications for PLA composites.

Preparation of environmentally friendly ionic liquids-toughened polylactic acid/nanofibrillated cellulose composites with high strength and precipitation resistance

Polylactic acid (PLA) is one of the most promising biodegradable materials, but poor toughness severely limits its application. Ionic liquids (ILs) have excellent plasticizing effects on PLA, but strength reduction and plasticizer precipitation remain worrisome. Herein, nanofibrillated cellulose (NFC), with excellent morphology, high modulus and strength, was prepared to reinforce PLA plasticization systems. Moreover, its numerous surface hydroxyl groups were tailored to bond with ILs, reducing plasticizer precipitation. The different sulfonation degrees of NFCs (low LSNFC, medium MSNFC, high HSNFC) and the influence of NFC amounts (0–7 wt%) on the mechanical, thermal and plasticizer precipitation properties of PLA composites were investigated. The results indicate that network-like C2/C3-sulfonated NFCs were successfully prepared through simple processing steps. Noteworthy, the tensile elongations of PLA composites increased with the addition of IL-XSNFC (all three degrees), with no significant reduction in tensile strength and modulus. The addition of 7 wt% IL-HSNFC resulted in an elongation of 25.01 % for PLA composites, which is 3.6 times that of pure PLA. Adding 3 wt% IL-MSNFC achieved ultra-high impact toughness of 3.19 kJ/m2, nearly double that of pure PLA. Interestingly, with increasing sulfonation degree, the amount of ILs precipitation in PLA composites significantly decreased. The precipitation rate of the PLA composite with IL-HSNFC is only 24 % of the counterparts with IL-NFC. This work presents an innovative method to improve interface compatibility, providing a new strategy to reduce plasticizer precipitation and broaden the application scope of PLA.

Contact Antibacterial and Biocompatible Polymeric, Composite with Copper Zeolite Filler and Copper Oxide, Nanoparticles: A Step Towards New Raw Materials for the Biomedical Industry

This paper introduces a simple procedure for developing composite materials with antibacterial and biocompatible properties using polylactic acid (PLA) and polypropylene (PP). These composites incorporate three variants of zeolites in different percentages as filler agents: pure zeolite (PZ), copper ion-saturated zeolite (LZ), and copper-ion-saturated zeolite with copper oxide nanoparticles (LZ-nCu). The composites were prepared by the extrusion method and manufactured by injection molding. The impact of these zeolites on various material properties was evaluated, including morphology, thermal stability, mechanical properties, antibacterial capacity, biocompatibility, water absorption, and chemical resistance. The results demonstrated that (i) the incorporation of zeolite into the PP matrix improved thermal stability and increased the tensile modulus of the composites. For PLA-based composites, although there was a slight decrease in these values compared to pure PLA, they remained within acceptable ranges; (ii) zeolite LZ and LZnCu composites at 5 and 10% by weight effectively inhibited the growth of Gram-positive and Gram-negative bacteria within a maximum of 2 hours of contact; and (iii) composites containing 10% by weight of PZ, LZ, or LZ-nCu showed reduced mechanical properties due to a tendency to form agglomerates. Additionally, LZ and LZ-nCu composites with the same percentage proved highly toxic to human gingival fibroblast cells (HGFs). PLA/LZ-nCu at 5% and PP/LZ at 5% composites exhibited antibacterial properties with bactericidal effects upon contact, high biocompatibility, and lower water absorption compared to the pure polymeric matrix. These results highlight the operational effectiveness of the procedure and suggest the potential of these composites in biomedical applications, such as in vitro dentistry, without contamination risks.

3D‐printing continuous plant fiber/polylactic acid composites with lightweight and high strength

AbstractContinuous plant yarn‐reinforced polylactic acid (PLA) composites were produced through in situ 3D printing, focusing on how plant fiber attributes influence the crystallization, mechanical, and rheological properties of the printed composites. The aim of this study was to assess the viability of plant fibers as substitutes for synthetic ones in engineering additive manufacturing. Plant fibers promoted the crystallization of PLA due to their shear induction and nucleation agent induction effects. The inherent triangular void defect during printing decreased with increasing plant fiber‐volume fraction. Rheological analysis revealed a transition to more elastic behavior post‐fiber addition, indicating solid‐like properties. The tensile strength of flax fiber‐yarn/PLA composite (volume fraction of 50.79%) was 342.37% higher than that of pure PLA, with a 22.2% lower density than pure PLA. Flax fiber demonstrated a superior reinforcement effect than carbon fiber in compressive strength for 3D printed honeycomb sheets with lower energy consumption and footprint. Optimizing fiber characteristics holds promise for high‐performance 3D‐printed natural fiber composites, particularly in vehicle applications.Highlights Plant fiber/polylactic acid (PLA) composites were in situ printed with a volume fraction of 50.79%. Plant fibers promoted the crystallization of PLA during the printing process. The tensile strength of flax fiber/PLA increased by 342.3% with a 22.2% lower density than PLA. Flax fiber showed a better reinforcement than carbon fiber in a compressive test of printed honeycomb.

The Effect of the Surface Treatment on TiO2 Particles When Used as a Filler on Crystallization and Mechanical Properties of Polylactic Acid Composites. Case of Study: Silane Coupling Agents and Dicarboxylic Acids Were Used as Surface Modifiers

ABSTRACT This article analyzes the effect of the type of surface modification (using silane coupling agents and dicarboxylic acids) on titanium dioxide particles used as fillers in polylactic acid composites, which were exposed to a photodegradative process. The thermomechanical properties of the composites were analyzed; it was found that the silane coupling agent with Imidazole allowed the composites to have Young’s modulus values 60% lower than the composite without filler. On the other hand, the crystallization rate was 30% higher for composites with azelaic Acid attached to TiO2 particles than for composites without filler at a cooling rate of 5°C min−1. Once degraded composites containing azelaic acid were the least brittle, with a minor increment in Young’s Modulus compared to pure polylactic acid composites. When a mixture of modified titanium dioxide particles (with imidazole and either azelaic acid or pimelic acid) was used, there was a synergistic effect regarding photostability.

3D printing of biodegradable biocomposites based on forest industrial residues by fused deposition modeling

This study investigated the impact of industrial forest residues (IFR) type and proportion on 3D-printed biocomposites (BC). Fused deposition modeling (FDM) produced BC containing up to 20 % Jack pine sawdust, wood ashes, cellulose fibers, and polylactic acid (PLA). The BC thermal stability, surface chemistry, microstructure, and physical and mechanical were investigated. Thermal stability investigations revealed that adding IRF resulted in a decline in the PLA degradation temperature, an increase in the residual mass, a decrease in the glass transition temperature, and an improvement in crystallinity. Add IRF to PLA showed an important reduction in ductility, a consistent reduction of the tensile and flexural strengths with increasing proportion but only a slight or a non-significant reduction the modulus of elasticity. Adding forest waste filler to pure PLA increased the water absorption (WA) and dimensional accuracy (TA) of the biocomposites, which was expected due to the hydrophilic character of fillers. The microstructural analysis demonstrated that a higher filler level resulted in a greater porosity, roughness, and visible filler pull-out on the filament and printed parts surfaces. Surface chemistry analysis suggested poor interactions between the PLA and the fillers and consequently poor interfacial adhesion. Furthermore, the rheological investigations confirmed that the complex viscosity and storage modulus of PLA-Jack pine's sawdust and PLA-cellulose fibers increased with filler. In contrast, the PLA-wood ashes showed opposite results. Using 3D-printed biodegradable biocomposites provided a sustainable option for reducing dependence on non-renewable plastic, valorizing the value chain of forest products, and promoting the circular economy.

Physico-mechanical Properties of Nano Bio-films For Application in Food Packaging

Petroleum-based packaging has long dominated the packaging industry, raising environmental concerns. As a result, the packaging industry has started using nano bio-plastics. Incorporating nanoparticles, nano bio-plastic packaging helps in prolonging product shelf life. Additionally, packaging manufactured of nano bio-plastic is made of biodegradable polymers. Nano bio-films made from polylactic acid (PLA) and nanoclay were produced using a solvent casting process. 1.0%, 3.0% and 5.0% (wt.) of nanoclay were added to the PLA solution. The mechanical, chemical, morphological and transparency properties of nano bio-films were investigated. To improve their suitability for food packaging applications, tensile test, Fourier-transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM) and UV-barrier test were performed. With tensile strength (TS) of 30.36 MPa and elongation at break (EAB) of 7.05%, respectively, nano bio-films with 3.0 wt. % nanoclay demonstrated higher mechanical properties than pure PLA film with about 35% of increment. In aspects of FTIR analysis, no significant differences were found with both nano bio-films and pure PLA film. The SEM morphology shows that adding nanoclay at 3.0 wt. % improves the adhesion between the PLA matrix and the nanoclay. The addition of nanoclay had a minimal impact on the PLA film's transparency, and it was interesting to see that nanoclay concentration of 1.0 wt. % and 3.0 wt. % had roughly the same light transmission values of 84.86% and 83.95%, respectively. According to the findings of this study, the PLA nano bio-film with 3.0 wt% nanoclay exhibits the optimum physico-mechanical properties.

Comparative study of blending techniques in polylactic acid/cellulose nanofibrils green composites for benchtop 3D printing filaments

AbstractAdditive manufacturing for polylactic acid (PLA) reinforced with cellulose nanofibrils (CNF) could unlock fabrication of specialized and user‐specific biomedical devices. However, the process of combining PLA and CNF is challenging and proves complicated with possible irreversible CNF agglomeration and organic solvents leftover, particularly when involving solvent‐casting technique. Direct melt‐blending can mitigate these issues, but there are few reports of a single‐step melting and extrusion process to produce ready‐to‐use 3D printing filaments. This study compares the distribution of CNF fillers within the PLA matrix in PLA/CNF composites made by direct melt‐blending into filaments using a benchtop filament maker, and by solvent‐casting followed by extrusion into filaments. The filaments were 3D‐printed via fused deposition modeling (FDM), followed by tensile testing, morphology, and other characterizations. Uneven filament diameters were observed for the composite filaments prepared via solvent‐casting because of severe agglomeration, resulted in poor printability and tensile properties of filaments and 3D‐printed samples. Direct melt‐blended filament diameters were consistent, resulted in only slight decrease of tensile properties compared to pure PLA, contributing to the highest maximum tensile strength of 3D‐printed sample of 51.47 ± 1.73 MPa at 5% CNF loading. Morphology revealed good integration of CNF into PLA matrix starting at 3% CNF loading. Direct melt‐blending was comparable to the conventional methods, which enables simpler PLA/CNF composite preparation especially for 3D printing.Highlights Better dispersibility achieved by direct melt‐blending than by solvent‐casting. PLA/CNF filaments produced via solvent‐casting suffered severe agglomeration. Direct melt‐blended PLA/CNF5% yielded the highest maximum tensile strength. Morphology reveals good CNF‐PLA integration starting at 3% of CNF loading. Worsened agglomeration causing increased number of voids observed at 10% CNF.

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.

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.

Study on the laser sintering process of veined red snail/polylactic acid composite powder

Drawing on the composition of shells and the microstructure of cross-laminated sheets, laser sintering technology was used to prepare laser-sintered fabrications of veined red snail powder as an inorganic material and polylactic acid (PLA) as an organic material. The process was optimized using the response surface method based on one-way experiments by adding veined red snail powder. At a 13.27 W laser power, 1.2 m/s scanning rate, 0.17 mm scanning spacing, and 0.23 mm delamination thickness, the bending strength of the veined red conch powder/PLA composite powder parts reached 8.53 ± 0.15 MPa, with an error of only 1.7% from the model’s predicted value. Under these process conditions, the characterization of laser-sintered parts with 0, 5, 10, 15, 20, and 25 wt% veined red snail powder revealed that parts with 15 wt% exhibited optimal mechanical properties, showing a 155.9% improvement over pure PLA parts.

Synchronously enhanced flame retardancy and mechanical properties of polylactic acid via in-situ assembly of polyphosphazene nanoparticles on ammonium polyphosphate

Polylactic acid (PLA) exhibits wide potential applications in many fields ranging from textile, packaging material to biomedical devices. However, the relatively low mechanical properties and inflammability are obstacles to the expansion of its application. Here, a kind of polyphosphazene nanoparticles with tannic acid (TA) as template, hexachlorocyclotriphosphazene (HCCP) and 4,4′-Sulfonyldiphenol (BPS) as comonomers were prepared (named as HTB), and then combined with ammonium polyphosphate (APP) to enhance the comprehensive properties of PLA composites. The introduction of HTB strengthened the interfacial adhesion of composites via constructing the hydrogen bond interaction between PLA and APP, promoting the homogenous dispersion of APP in the composite and the formation of APP network. The flame retardant measurements presented that incorporating 10 wt% APP and 5 wt% HTB in PLA increased the limit oxygen index (LOI) value to 31.0% and endowed the composite with the V-0 rating of UL-94 test and simultaneously, the peak of heat release rate (PHRR) and total heat release (THR) of the composite decreased by 14.2% and 13.2% compared with pure PLA. Specially, there was almost no melt drip appeared during the combustion process, which was distinctly different from the combustion behavior of the composite containing only 20 wt% APP with the V-2 rating of UL-94 test. The uniform dispersion of APP in the PLA matrix and the strong interfacial adhesion between APP and the PLA matrix contribute to the enhancement of the mechanical properties of composites, and the elongation at break, Young’s modulus and impact strength of the composite were increased by 52.9%, 7.6% and 24.2%, respectively. The present study offers novel insights for the trade-off between flame retardancy and mechanical properties with PLA composites.

Antibacterial performance of biodegradable polymer and hazelnut husk flour antibacterial biofilm with silver nanoparticles

The antibacterial performance of biocomposite films prepared from lignocellulosic waste (hazelnut husk or hazelnut leafy green cover) modified with silver nanoparticles and polylactic acid (PLA) was determined. The amount of hazelnut husk in the PLA matrix ranged from 10 to 40% by weight in 10% increments. The composite pellets were produced using a twin-screw extruder. Biocomposite films of 0.6 mm x 40 mm x 200 mm were produced from the pellets in a laboratory hydraulic hot press. The surfaces of the modified hazelnut husk and biocomposite specimens were analyzed by scanning electron microscopy (SEM) and inductively coupled plasma optical emission spectrometry (ICP-OES). The antibacterial activity of the biocomposite films against Staphylococcus aureus bacteria was determined using the ASTM E 2149 (2020) method. The antibacterial activity of the biocomposite films increased noticeably with the addition of hazelnut husk modified with the silver nanoparticles. Compared to the pure PLA film, the biocomposite films with 10 wt% modified husk flour showed the lowest antibacterial activity (31.3%) against S. aureus over 24-h while the films with 40 wt% showed the highest antibacterial activity (99.9%). The biocomposite films made of hazelnut husk flour with silver nanoparticles and PLA matrix could be considered for food packaging applications.

Inclusion of modified nano-magnesium hydroxide as an adjuvant flame retardant in the development of PLA/hydroxyapatite nanocomposites

For the preparation of thermal stable and flame-retardant polylactic acid (PLA) nanocomposites two new modified nano-structures including imide-carboxylated chitosan modified Mg(OH)2 (ICMH) and imide-silane functionalized hydroxyapatite nanoparticles (ISHA) were prepared. The structure, morphology, and properties of ICMH and ISHA were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA). The PLA nanocomposites were prepared via solution casting method. The results of Transmission electron microscopy (TEM) and SEM indicated a homogeneous structure for the PLA nanocomposites. The TGA results revealed that the presence of hydroxyapatite nanoparticles (HA) led to increase the thermal resistance of the PLA nanocomposites containing Mg(OH)2 (MDH). Compared to pure PLA, the Tmax value of the PLA sample containing 3 wt% of each filler (the PMH6 sample) enhanced from 364°C to 372°C. The results from the microscale combustion calorimeter (MCC) test illustrated that the key parameter values of the PLA nanocomposites were reduced, as compared to the pure PLA. The peak heat release rate (pHRR) and heat release capacity (HRC) values of PMH6 decreased 27% and 35%, respectively, as compared to the pure PLA. Also, flammability of PMH6 was reduced, as compared to the pure PLA, with UL-94 V-1 rating and LOI value 26.8%. Furthermore, the tensile strength of the mentioned sample increased from 36.04 MPa to 38.58 MPa.

Novel thermal-regulation and temperature-responsive controlled-release fibermats with porous sheath-core structures

Active regulation of the wound microenvironment as well as on-demand drug delivery have proven to be effective ways to accelerate wound healing, and the development of advanced textiles offers feasibility. A novel fibermat with thermal-regulation and temperature-responsive controlled-release properties was fabricated by using coaxial electrospinning, consisting of porous sheath-core polylactic acid (PLA)/ polyethylene glycol (PEG) fibers. The pore generation in the PLA shell of the PLA/PEG fiber was achieved through a phase separation method. The fiber diameter and pore size of the obtained fiber could be controlled by adjusting the flow rate of shell solution during electrospinning. Increasing the flow rate of shell solution form 0.8 mm·min-1 to 1.4 mm·min-1 resulted in an increase in fiber diameter from 4.8 μm to 15.3 μm, and an increase in pore size from 59.4 nm to 305.6 nm. Due to the high enthalpy and coverage of the PEG core, the PLA/PEG fibermats exhibited excellent thermal-regulation performance, with a surface temperature that was 2.5 °C- 5.6 °C lower than that of pure PLA fibermat during heating process. On-demand release was achieved by directly controlling the core layer of the coaxial PLA/PEG fiber through temperature. The hydrophobicity of the PLA shell initially reduced burst release, followed by increased release as the temperature reached the phase transition temperature of PEG. Furthermore, this advanced fibermat demonstrated desirable moisture permeability, appropriate mechanical properties and good thermal stability, indicating broad potential applications in medical and health fields.

Mechanical Properties and Flammability Analysis of Wood Fiber Filled Polylactic Acid (PLA) Composites Using Additive Manufacturing

ABSTRACT Natural fibers, such as wood fibers, can substitute for synthetic fibers in various applications due to their low environmental impact, cost-effectiveness, and outstanding mechanical properties as rapid-growing materials and renewable resources. This paper aims to investigate the mechanical properties of 20% wood fiber as a reinforcement material in polylactic acid (PLA) using an additive manufacturing approach. The samples were fabricated using 3D printing techniques. The relevant parameters included the orientation of printing in X, Y, and Z directions, with the percentage of infill set to be 100%. The findings indicated that bio-composites and their adopted printing orientations confirmed the significant effects on the mechanical properties. Pure PLA possessed superior properties in all directions compared to wood/PLA. The highest values were 50.33 MPa for tensile strength and 94.36 MPa for flexural strength, both achieved in Y orientations. However, composites showed an improvement in tensile and flexural moduli in X orientation with 1395.40 MPa, and 2937.72 MPa for Young and flexural modulus, respectively. In the flammability test, wood/PLA bio-composites were ignited easily with reduced smoke production compared to the neat PLA. Wood/PLA bio-composites exhibited high stiffness, and their mechanical properties were influenced by many factors, such as percentage of weight fraction, wood type, and printing orientations.

Valorization of Cellulosic Waste from Artichoke for Incorporation into Biodegradable Polylactic Acid Matrices.

This study presents the development of ecological compounds using polylactic acid (PLA) and artichoke flour with the aim of obtaining materials with properties like commercial PLA. PLA biocomposites with different concentrations of green artichoke (HV) and boiled artichoke (HH) (1, 3, 5, 7, 10 and 20% by weight) were manufactured through an extrusion and injection process. Structural, mechanical, physical and color tests were carried out to analyze the effect of lignocellulosic particles on the biopolymeric matrix. The Shore D hardness, elongation at break and heat deflection temperature (HDT) of the PLA/HV and PLA/HH samples showed similar values to pure PLA, indicating that high concentrations of both fillers did not severely compromise these properties. However, reductions in the tensile strength, impact strength and Young's modulus were observed, and both flours had increased water absorption capacity. FTIR analysis identified the characteristic peaks of the biocomposites and the ratio of the groups regarding the amount of added filler. The SEM revealed low interfacial adhesion between the polymer matrix and the filler. This study represents a significant advance in the valorization and application of circular economy principles to agricultural waste, such as artichoke waste. PLA/HV biocomposites make a substantial contribution to sustainable materials technology, aligning with the goals of the 2030 agenda to reduce environmental impacts and promote sustainable development.

Assessing polylactic acid nanofibers with cellulose and chitosan nanocapsules loaded with chamomile extract for treating gram-negative infections.

This study presents the development and characterization of a novel nanocomposite wound dressing material based on polylactic acid (PLA) nanofibers incorporating chitosan nanocapsules loaded with chamomile extract and cellulose nanoparticles. The nanofibers were fabricated using a three-step synthesis and electrospinning techniques, resulting in uniform, bead-free fibers with an average diameter of 186 ± 56nm. Fourier-transform infrared spectroscopy confirmed the successful incorporation of all components, while tensile strength tests demonstrated improved mechanical properties by adding nanoparticles. Water contact angle measurements revealed enhanced surface wettability of the PLA-Cellulose-Chitosan complex compared to pure PLA nanofibers. In vitro biocompatibility assessments using MTT assays showed excellent cell viability and proliferation, with the optimized composite exhibiting the best performance. Scanning electron microscopy imaging confirmed robust cell adhesion and interaction with the nanofibers. The nanocomposite demonstrated significant antimicrobial activity against Escherichia coli, with a 20mm inhibition zone observed for chamomile extract-loaded samples. Additionally, the material showed superior hemostatic ability compared to commercial gauze and high hemocompatibility. These comprehensive results indicate that the developed nanocomposite is a promising candidate for advanced wound management applications, offering a multifunctional approach to wound healing by combining antimicrobial activity, cell compatibility, and hemostatic properties.