PLA Fibers Research Articles

Yenilenebilir Kaynaklardan Elde Edilen Doğal Liflerin Biyodegradasyon Özellikleri

The interest in natural fibres in non – textile applications has increased as a result of the search for new renewable materials. Especially attractive for environmental safety demands are biodegradable and renewable fibres such as lignocellulose fibres and biopolymers such as PLA.
 The analysis of their biodegradation is often taken as a standard measure for environmentally friendly textile materials. Therefore, the aim of this paper is to investigate the biodegradation properties of Jute and PLA fibres by soil burial test. The fibres were exposed to the farmland soil for 11 days. The efficiency of the biodegradability was determined by comparison of mass loss, mechanical properties (finesses and tenacity) and morphological analysis by SEM microscope. With the purpose of a better understanding of biodegradation, the number of total fungi and bacteria in the soil is also determined.

Synergistic Combination of Antimicrobial Peptides and Cationic Polyitaconates in Multifunctional PLA Fibers.

Combining different antimicrobial agents has emerged as a promising strategy to enhance efficacy and address resistance evolution. In this study, we investigated the synergistic antimicrobial effect of a cationic biobased polymer and the antimicrobial peptide (AMP) temporin L, with the goal of developing multifunctional electrospun fibers for potential biomedical applications, particularly in wound dressing. A clickable polymer with pendent alkyne groups was synthesized by using a biobased itaconic acid building block. Subsequently, the polymer was functionalized through click chemistry with thiazolium groups derived from vitamin B1 (PTTIQ), as well as a combination of thiazolium and AMP temporin L, resulting in a conjugate polymer-peptide (PTTIQ-AMP). The individual and combined effects of the cationic PTTIQ, Temporin L, and PTTIQ-AMP were evaluated against Gram-positive and Gram-negative bacteria as well as Candida species. The results demonstrated that most combinations exhibited an indifferent effect, whereas the covalently conjugated PTTIQ-AMP displayed an antagonistic effect, potentially attributed to the aggregation process. Both antimicrobial compounds, PTTIQ and temporin L, were incorporated into poly(lactic acid) electrospun fibers using the supercritical solvent impregnation method. This approach yielded fibers with improved antibacterial performance, as a result of the potent activity exerted by the AMP and the nonleaching nature of the cationic polymer, thereby enhancing long-term effectiveness.

Accelerating the Biodegradation of Poly(lactic acid) through the Inclusion of Plant Fibers: A Review of Recent Advances.

As the global demand for plastics continues to grow, plastic waste is accumulating at an alarming rate with negative effects on the natural environment. The industrially compostable biopolymer poly(lactic acid) (PLA) is therefore being adopted for use in many applications, but the degradation of this material is slow under many end-of-life conditions. This Perspective explores the feasibility of accelerating the degradation of PLA through the formation of PLA-plant fiber composites. Topics include: (a) key properties of PLA, plant-based fibers, and biocomposites; (b) mechanisms of both hydrolytic degradation and biodegradation of PLA-fiber composites; (c) end-of-life degradation of PLA and PLA-plant fiber composites in aerobic and anaerobic conditions, relevant to compost, soil and seawater (aerobic), and landfills (anaerobic); and (d) sustainability and environmental impact of PLA and PLA-plant fiber composites, as evaluated using life cycle assessment. Additional degradation modes, including thermal and photodegradation, which are relevant during processing and use, have been omitted for clarity, as have other types of PLA biocomposites. Multiple studies have shown that the addition of some types of plant fibers to PLA (to form PLA biocomposites) accelerates both water transport in the material and hydrolysis, presenting a possible avenue for improving the end-of-life degradation of these materials. To facilitate the continued development of materials with enhanced biodegradability, we identify a need to implement testing protocols that can distinguish between different degradation mechanisms.

Effective removal of arsenite from water using polylactic acid ZIF-8 biocomposite nanofiber

Water purification from As(III)-contaminated groundwater is difficult but highly needed. Herein, a new polylactic acid ZIF-8 biocomposite nanofiber mat (ZIF-8@PLA/NFM) was fabricated using an electrospinning technique for As(III) decontamination. The active component, ZIF-8 nanoparticles, are uniformly embedded in sustainable PLA fibers and can be rapidly contacted by As(III), achieving fast kinetics and high utilization of nanoparticles. The removal experiments show that the ZIF-8@PLA/NFM can effectively remove As(III), especially in combination with H2O2. The 50%-ZIF-8@PLA/NFM with 1 mM H2O2 reduced 1000 μg/L As(III) to less than 10 μg/L in just 5 min through the synergy of oxidation and adsorption. The maximum sorption capacity for As(III) on 50-ZIF-8@PLA/NFM was 11.61 ± 0.99 mg/g, which increased to 39.25 ± 3.84 mg/g with the addition of H2O2. It performed well in the pH range of 4–9. The combination of H2O2 broadened its effective pH operating range (3–10) as well as enhanced interference resistance, enabling deep removal of As(III) across a wide range of water environments. The As(III)-spiked natural water (100 μg/L) could be purified to drinking standard level by ZIF-8@PLA/NFM within 60 min. In combination with H2O2, the removal efficiency was reduced by only 1.5% at the fifth reuse. Macroscopic experiments and microscopic characterization suggest that the adsorption follows the inner-sphere complexes mechanism. The study provides a novel approach for the fabrication of efficient, easy-to-use, and sustainable MOFs-based biocomposite for As(III) decontamination.

Selüloz ve PLA Biyopolimer Nonwoven Malçların Toprak Sağlığına Etkisi

The nonwoven mulches produced from regenerated viscose and PLA fibres as well as conventional agro foil were placed on the soil by randomly arranged blocks of four replication plots. After 50 days, the soil samples beneath each mulch and on the control field were collected, where the bacteria and fungi population as well as the physio-chemical properties of the soil were measured. The severe reduction in bacterial population in soil under the agro foil and mulches made of PLA fibres occurs due to the prevalence of high soil temperature. The bacterial population of soil beneath the mulches made of viscose fibre significantly increased due to favourable anaerobic conditions, respectively soil temperature and moisture. Under all mulches, compared to the control field, a higher fungal population was observed. The fungal population under the nonwoven mulch produced by viscose fibres was 161% higher in comparison to the control field. The available nutrient contents of soils under the nonwoven mulches were higher compared to the control field. The control field showed higher available nutrient contents of soil than the field covered by conventional agro foil.
 The results of the study reveal that usage of nonwoven mulches made of viscose fibres is most appropriate for short-term mulching application since successfully increases microbial population and improves the physio-chemical properties of soil.

Effect of Post-Drawing Thermal Treatment on the Mechanical Behavior of Solid-State Drawn Poly(lactic acid) (PLA) Filaments

In this work, two commercial extruded filaments for 3D printing obtained from different NatureWorks PLA resins (Ingeo™ Biopolymer 3D850 and Ingeo™ Biopolymer 4043D) were solid-state drawn at varying temperatures and subsequently heat treated by annealing. The aim was to analyze the effect of post-processing of industrial fibers (solid-state drawing and annealing treatment) with varied composition (PLA grades with different contents of D-isomer) on the mechanical performance and thermal stability of the obtained PLA fibers. Morphological, thermal, and mechanical characterizations were performed for the undrawn filaments and drawn fibers, both before and after heat treatment. Drawn fibers presented a fibrillar core–shell structure, and their mechanical properties were greatly improved with respect to undrawn filaments in accordance with their higher crystallinity. The resin with the higher content of D-isomer (4043D) resulted in lower crystallinities with a subsequent decrease in mechanical properties. After heat treatment, drawn fibers exhibited completely different behaviors depending on the PLA resin, with 3D850 fibers being much more stable than 4043D fibers, which underwent molecular orientation upon drawing rather than crystallization. The solid-state drawn fibers obtained herein are comparable to commercial fibers in terms of mechanical properties.

Production of PLA fibers with surface modifications and silver nanoparticle coating to impart antibacterial activity

Production of PLA fibers with surface modifications and silver nanoparticle coating to impart antibacterial activity

Effect of Melt Jet Spinning Process on PLA/PBS Blend Nonwoven Fabric Production

The melt jet spinning process has been used for production of consistently fine nonwoven fibers. The process was applied to produce the biodegradable nonwoven fabric such as poly (lactic acid) (PLA). However, the rigid nonwoven PLA fibers limited the application of nonwoven. To improve the nonwoven fiber flexibility, the fabrication of PLA/PBS blend nonwoven fabric using melt jet spinning process under various process conditions was studied. In the melt jet spinning process, the nozzle temperature is varied between 250 to 280 °C. The performance metric evaluation is comprised of fiber diameter, fiber crystallinity, mechanical property and contact angle. The fiber diameter, crystallinity and tensile strength of PLA/PBS blend nonwoven fabric decreased with increasing nozzle temperature. The optimum process condition of the PLA/PBS nonwoven fabric production was found at nozzle temperature of 280 °C to produce the nonwoven fiber with average diameter of 5.1 μm. The forming temperature has no effect on the hydrophilic properties of PLA/PBS nonwoven fabric. The melt jet spinning process was successfully applied for the biodegradable polymer to produce the environmentally friendly products.

Enzymatic Degradation of Polylactic Acid Fibers Supported on a Hydrogel for Sustained Release of Lactate.

The incorporation of exogenous lactate into cardiac tissues is a regenerative strategy that is rapidly gaining attention. In this work, two polymeric platforms were designed to achieve a sustained release of lactate, combining immediate and prolonged release profiles. Both platforms contained electrospun poly(lactic acid) (PLA) fibers and an alginate (Alg) hydrogel. In the first platform, named L/K(x)/Alg-PLA, lactate and proteinase K (x mg of enzyme per 1 g of PLA) were directly loaded into the Alg hydrogel, into which PLA fibers were assembled. In the second platform, L/Alg-K(x)/PLA, fibers were produced by electrospinning a proteinase K:PLA solution and, subsequently, assembled within the lactate-loaded hydrogel. After characterizing the chemical, morphological, and mechanical properties of the systems, as well as their cytotoxicity, the release profiles of the two platforms were determined considering different amounts of proteinase K (x = 5.2, 26, and 52 mg of proteinase K per 1 g of PLA), which is known to exhibit a broad cleavage activity. The profiles obtained using L/Alg-K(x)/PLA platforms with x = 26 and 52 were the closest to the criteria that must be met for cardiac tissue regeneration. Finally, the amount of lactate directly loaded in the Alg hydrogel for immediate release and the amount of protein in the electrospinning solution were adapted to achieve a constant lactate release of around 6 mM per day over 1 or 2 weeks. In the optimized bioplatform, in which 6 mM lactate was loaded in the hydrogel, the amount of fibers was increased by a factor of ×3, the amount of enzyme was adjusted to 40 mg per 1 g of PLA, and a daily lactate release of 5.9 ± 2.7 mM over a period of 11 days was achieved. Accordingly, the engineered device fully satisfied the characteristics and requirements for heart tissue regeneration.

Preparation and characterization of novel poly (lactic acid)/calcium oxide nanocomposites by electrospinning as a potential bone tissue scaffold

Calcium oxide nanoparticles (n-CaO) ca. 22 nm were obtained from eggshell waste. The n-CaO was incorporated into the PLA matrix in 10 and 20 wt% of filler content by electrospinning process to get PLA/n-CaO fibers with homogenous morphology and diameter as a potential use in scaffold for bone tissue regeneration. The incorporation of n-CaO into PLA modifies the mechanical properties, having a reinforcement effect on the matrix. The Young modulus for PLA/n-CaO nanocomposites increased between 122 and 138 % concerning neat PLA fibers, showing a more rigid behavior. The PLA/n-CaO nanocomposite fibers showed in vitro bioactivity, capable of inducing the precipitation of hydroxyapatite (HA) layer in the fiber surface after seven days in SBF solution. The biocidal and biological properties of PLA/n-Cao with 20 wt% showed a 30 % reduction in bacterial viability against S. aureus and 11 % against E. coli after 6 h of bacterial exposure. Furthermore, the fibers did not show a cytotoxic effect on the bone marrow ST-2 cell line, allowing cell adhesion and proliferation in the RPMI medium. The PLA/n-CaO with 20 wt% of nanoparticles showed a higher capacity to promote osteogenic differentiation, significantly increasing the alkaline phosphatase (ALP) expression after seven days compared to PLA and cell control. The in vivo analysis corroborated the biocompatibility of the prepared scaffolds; the presence of n-CaO in PLA reduced the formation of fibrous encapsulation of the material, improving the healing process. These results validated using n-CaO to enhance the functionality of polymer matrices as a PLA, bringing bioactive, biocide, and biocompatible properties, opening a new and interesting route to develop new biomaterials as a scaffold for bone tissue engineering.

The Influence of Processing Temperature on the Tensile Properties of Melt-Spun PLA Fibres and their Self-Reinforced Composites

The temperature during the consolidation of self-reinforced PLA composites has a significant effect on their mechanical properties. In the present work, the effect of the consolidation or processing temperature on the properties of melt-spun, highly oriented PLA fibres is experimentally studied through single fibre tests. It is shown that the Young’s modulus and strain to failure of PLA fibres increases with exposure to consolidation / processing temperature, and the strength decreases more drastically. Using these data and findings from earlier studies, it is demonstrated that the dependence of the tensile properties of self-reinforced PLA composites on the processing temperature can be directly predicted from the single PLA fiber properties as a function of the processing temperature. This prediction holds true provided that the tensile properties of both the PLA fibers and self-reinforced PLA composites are measured using the same cross-head speed or strain rate.

Preparation of modified polylactic acid fiber containing anti‐hydrolysis agents

AbstractPolylactic acid (PLA) is a promising alternative to petroleum‐based polymers due to its biodegradability. However, its low mechanical properties in the presence of moisture are a challenge for textile applications. In this study, we investigated the effects of two anti‐hydrolysis agents, an epoxy‐based agent (ADR) and an aromatic carbodiimide‐based agent (ZIKA), on the mechanical properties and hydrolysis resistance of PLA fibers. A melt‐spinning process was used to prepare anti‐hydrolysis fibers by adding 0.3 and 0.5 wt% of ADR and ZIKA to PLA. The topology of ADR/PLA and ZIKA/PLA was determined by Fourier transform infrared spectroscopy (FT‐IR). Analysis of the compound chip revealed that ADR formed a branched chain in PLA, while ZIKA produced a linear molecular structure. The hydrolysis resistance of the fibers was evaluated by analyzing their crystallinity, hydrothermal shrinkage behavior, morphology, and tensile strength. ZIKA/PLA fibers showed higher orientation and crystallinity than ADR/PLA fibers. After hydrolysis, the tensile strength of ADR 0.5%/PLA fibers decreased by 31%, while that of ZIKA 0.5%/PLA fibers decreased by only 5% due to the linear molecular structure of ZIKA/PLA. Our findings indicate that ZIKA is more effective than ADR in producing hydrolysis‐resistant PLA fibers with high crystallinity, orientation, and mechanical durability.

Stereocomplex formation of a poly(D-lactide)/poly(L-lactide) blend on a technical scale

Abstract Poly(D-lactide) (PDLA) and poly(L-lactide) (PLLA), both available on the market, are blended on a technical scale. Using a special process control, the two materials are blended in a twin-screw extruder at a mass throughput rate of 2 kg/h, resulting in a stereocomplex Poly(-lactide) (PLA) blend. Thermal analysis indicates only one melting point at 235 °C. Both the Raman spectra and X-ray powder diffraction patterns show characteristic features for the stereocomplex PLA. With the available amount of this blend PLA fibers with technical strengths can be developed by melt spinning. As such, the application of the biopolymer PLA can be expanded, leading to substitute the conventional plastics for conserving both the resources and the environment.

Dyeing properties of polylactic acid fabric with disperse dyes of different structures using decamethylcyclopentasiloxane as non‐aqueous media

AbstractPolylactic acid (PLA) fibre, as a renewable and biodegradable synthetic polymer, is attracting increasing attention in the field of textiles. However, there are still some problems associated with PLA fibre dyeing, with a traditional water bath using disperse dyes restricting its industrialisation. Waterless dyeing, as a green and environmentally friendly dyeing method for PLA fibre, is expected to replace the traditional water bath dyeing method. However, the disperse dyes suitable for PLA fibre are different from those that are suitable for traditional poly(ethylene terephthalate) fibre. In the current study, the waterless dyeability of PLA fibre using disperse dyes with different chemical structures, and decamethylcyclopentasiloxane (D5) as the media, was investigated. First, the optimal dyeing process conditions of dye concentration, dyeing temperature, dyeing time and liquor ratio for PLA waterless dyeing were determined. The results indicated that the most suitable dyeing process conditions were: a dye concentration of 5%, dyeing temperature and time of 120°C and 40 minutes, respectively, and a liquor ratio of 1:10. Next, PLA was dyed with 10 disperse dyes with different structures using the determined optimum dyeing process conditions to compare their dyeing properties. The results showed that there were obvious differences in the K/S values for PLA dyed with dyes of different structures. The K/S values for PLA dyed with monoazo structure dyes were significantly higher than those for anthraquinones and heterocyclic structure dyes. Disperse dyes with a monoazo structure are suitable for PLA waterless dyeing. This study provides a research basis to develop suitable dyes for waterless dyeing PLA using D5 as the media.

Usage of 3D printing technology in centrifugal pumps and material selection

The fused deposition modeling (FDM) technique which is one of the 3D printing technologies was used to produce a centrifugal pump impeller. The fabrication and investigation of the impeller were preferred because of its complex geometry and the difficulties encountered in its production. The most commonly used ABS, HIPS, PLA, and carbon fiber filaments were preferred to compare and determine the most suitable material for the production of the impellers. Firstly, mechanical test specimens from four different materials were printed in the 3D printer according to standards. Then the tensile tests and quasi-static punch shear tests (QS-PST) were applied to determine the mechanical properties of the 3D printed parts. Also, the mechanical tests were repeated to some specimen with the different fillings to define the optimum fill rates. Secondly, the impellers were fabricated from four materials by using the 3D printer in determined fill rates. Then, these impellers were mounted in the actual pump system, and pump performance tests were performed. In the pump performance tests, the head, pump efficiency, and electric power parameters were measured against the flow rate for each impeller. Finally, the mechanical properties and pump performance of the impellers compared with the GG25 cast iron impeller which is produced by traditional technique. As a result, PLA was selected as the most appropriate material for the production of the impellers. Furthermore, PLA showed superior performance compared to others when price, production time, and product weight parameters were considered.

In Vitro Bone Differentiation of 3D Microsphere from Dental Pulp-Mesenchymal Stem Cells.

Bone defects lead to the structural loss of normal architecture, and those in the field of bone tissue engineering are searching for new alternatives to aid bone regeneration. Dental pulp-mesenchymal stem cells (DP-MSC) could provide a promising alternative to repair bone defects, principally due to their multipotency and capacity to fabricate three-dimensional (3D) spheroids. The present study aimed to characterize the 3D DP-MSC microsphere and the osteogenic differentiation capacity potential cultured by a magnetic levitation system. To achieve this, the 3D DP-MSC microsphere was grown for 7, 14, and 21 days in an osteoinductive medium and compared to 3D human fetal osteoblast (hFOB) microspheres by examining the morphology, proliferation, osteogenesis, and colonization onto PLA fiber spun membrane. Our results showed good cell viability for both 3D microspheres with an average diameter of 350 μm. The osteogenesis examination of the 3D DP-MSC microsphere revealed the lineage commitment, such as the hFOB microsphere, as evidenced by ALP activity, the calcium content, and the expression of osteoblastic markers. Finally, the evaluation of the surface colonization exhibited similar patterns of cell-spreading over the fibrillar membrane. Our study demonstrated the feasibility of forming a 3D DP-MSC microsphere structure and the cell-behavior response as a strategy for the applications of bone tissue guiding.

Effect of electrospun stereocomplex PLA fibers and modified cellulose nanocrystals on crystallization of poly(L‐lactic acid)

AbstractPoly(L‐lactic acid) (PLLA) is a biodegradable polymer that has attracted increasing attention due to its fantastic properties. Nevertheless, the disadvantages of PLLA, such as low crystallization rate and brittleness, limit its wide commercial applications. In the present work, electrospun stereocomplex PLA fibers (Sc‐fibers) and PLLA grafted cellulose nanocrystals (g‐CNCs) are prepared as nano‐fillers and then blended with PLLA matrix to prepare different nanocomposites. Both of nano‐fillers would accelerate the crystallization rate of PLLA, and as expected, g‐CNCs have much stronger nucleation ability towards PLLA than Sc‐fibers. Nevertheless, the crystallization of PLLA will decrease to some extent in the presence of both nano‐fillers of g‐CNCs and Sc‐fibers due to the preferential formation of stereocomplex crystals on the surfaces of CNCs. Moreover, the presence of nano‐fillers would enhance the mechanical properties of PLLA, such as the elongation at break can increase by four times after incorporating both g‐CNCs and Sc‐fibers. This work provides a new consideration for designing different nano‐fillers, especially for polymer matrices with low crystallization ability and brittleness.

Centrifugal Force-Spinning to Obtain Multifunctional Fibers of PLA Reinforced with Functionalized Silver Nanoparticles.

The design and development of multifunctional fibers awakened great interest in biomaterials and food packaging materials. One way to achieve these materials is by incorporating functionalized nanoparticles into matrices obtained by spinning techniques. Here, a procedure for obtaining functionalized silver nanoparticles through a green protocol, using chitosan as a reducing agent, was implemented. These nanoparticles were incorporated into PLA solutions to study the production of multifunctional polymeric fibers by centrifugal force-spinning. Multifunctional PLA-based microfibers were obtained with nanoparticle concentrations varying from 0 to 3.5 wt%. The effect of the incorporation of nanoparticles and the method of preparation of the fibers on the morphology, thermomechanical properties, biodisintegration, and antimicrobial behavior, was investigated. The best balance in terms of thermomechanical behavior was obtained for the lowest amount of nanoparticles, that is 1 wt%. Furthermore, functionalized silver nanoparticles confer antibacterial activity to the PLA fibers, with a percentage of killing bacteria between 65 and 90%. All the samples turned out to be disintegrable under composting conditions. Additionally, the suitability of the centrifugal force-spinning technique for producing shape-memory fiber mats was tested. Results demonstrate that with 2 wt% of nanoparticles a good thermally activated shape-memory effect, with high values of fixity and recovery ratios, is obtained. The results obtained show interesting properties of the nanocomposites to be applied as biomaterials.

Eumelanin‐Coated Aligned PLA Electrospun Microfibers to Guide SH‐SY5YCells Spreading, Alignment, And Maturation

AbstractDuring the development of the nervous system, neurons sense and respond to topographical and biochemical cues found in the brain's native environment. Such niche‐specific cues are pivotal for neural tissue formation and development and have been now widely exploited in neural tissue engineering to develop biologically‐inspired scaffolds able to trigger a desired neuronal behavior. In particular, anisotropic aligned fibers, recapitulating the design of extending axonal tracts or aligned fibers found in the extracellular environment, have emerged as ideal candidates to guide cell alignment and elongation along the substrate main axis as well as promote neuronal differentiation. Among natural polymers used for coatings, melanins, including eumelanin, have been shown to possess antioxidant, anti‐inflammatory, immunomodulatory, and photo‐protective properties. Here, aligned poly(lactic acid) (PLA) fibers are fabricated via electrospinning and then coated with eumelanin via spin coating. Eumelanin‐coated aligned PLA fibers are highly biocompatible and greatly influenced the adhesion, morphology, and spreading of SH‐SY5Y neuroblastoma cells. Furthermore, the eumelanin coating is crucial in promoting cell alignment at the cell‐material interface and SH‐SY5Y cell maturation towards a more mature neuronal phenotype.

The Effect of Alkaline Treatment to Pseudo-Stem Banana Fibers on the Performance of Polylactic Acid/ Banana Fiber Composite

ABSTRACT Banana fiber (BF) is a renewable resource which can be a good reinforcer to polylactic acid, enhancing the polymers stiffness and accelerating biodegradability rates. However, due to the difference in nature between banana fibers (hydrophilic) and polylactic acid (hydrophobic), a good adhesion between the fiber and the matrix cannot be achieved. To tackle the problem, the fibers were chemically treated using sodium hydroxide under three factors (temperature, concentration, and treatment time). The factors interactions were given by response surface methodology and the statistical interactions were observed by ANOVA. Alkaline effect on fiber’s morphology, composition, mechanical, and morphological properties of composites produced were observed. Young’s modulus values have increased substantially compared to untreated fiber’s composites, with a slight increase in the tensile strength values. However, the elongation at break values have slightly dropped with the fiber’s alkaline treatment. Scanning electron microscope observations had shown a successful removal of impurities (e.g. hemicellulose, wax) and between the fiber’s strands, and an improvement of surface structure. Fourier-transform infrared spectroscopy analysis showed the successful removal of impurities, and interaction between PLA and banana fibers.