Poly Lactic Acid Research Articles

Optimization and prediction of additively manufactured PLA-PHA biodegradable polymer blend using TOPSIS and GA-ANN

Recent years have seen the proliferation of fused deposition modeling (FDM) as a means of manufacturing biodegradable products, for different applications such as rigid packaging, agricultural and biomedical. Blends of Polyhydroxyalkanoates (PHA) and polylactic acid (PLA) have been investigated to ascertain their prospective applications through FDM. This paper includes three parameters that affect the build process: layer height, nozzle temperature, and flow rate. 3D printed PLA/PHA can be characterized mechanically, and process parameters can be optimized to maximize design functionality. The experimental setup utilized a Taguchi L9 design, and TOSPIS was employed to optimize the output results. Using TOPSIS analysis, 0.2 mm layer thickness, 195 °C nozzle temperature, and 100 % flow rate were found to be the most optimal initiation parameters. The Taguchi analysis was used to analyze the output responses, and it was found that layer height had the greatest influence on mechanical properties, followed by flow rate and nozzle temperature. The percentage elongation at break has been improved significantly by adding PHA i.e., 170 % compared to PLA (5–10 %). This paper presents a framework for in-depth mechanical characterization of PLA-PHA 3D-printed parts, along with methods for optimizing process parameters to achieve optimal performance, as well as tools for modeling output responses using GA-ANN with an accuracy of 95 %.

Preparation and Characterization of Waste Cotton Fabric Reinforced Polylactic Acid Green Composites with Multifunctional Properties in a Low-Carbon Process

The development and design of eco-friendly materials prove crucial for promoting the recycling of waste cotton textiles and reducing environmental pollution. In this study, waste cotton fabric (WCF) and polylactic acid (PLA) serve to produce cotton fabric-reinforced PLA composite material (CF/P). The CF/P is then integrated with traditional porous sound-absorbing materials to create a novel composite plate. This research highlights the potential of WCF reinforced plates for sound absorption and thermal insulation applications in the construction field of construction and reports the effects of variables such as hot pressing temperature, WCF mass fraction, and WCF layer alignment angle on the material properties. The optimum tensile strength, water absorption, and thermal conductivity of the prepared CF/P are 64.2 ± 1.8MPa, 1.98% ± 0.04%, and 0.03W/(m·K), respectively. By combining with porous sound-absorbing materials and modifying the layering structure of composite plates, its acoustic performance can be adjusted. The highest Sound Absorption Average (SAA) of plates with a multilayer composite structure is 0.67. Direct shaping through hot pressing diminishes the use of adhesives, thereby reducing costs and health hazards. This approach offers a practical and efficient solution for the recycling and repurposing of natural fibers.

Enhanced Phase Change Heat Transfer with Fused Deposition Modeling (FDM) Printed Pit and Pillar (Pi2) Arrays

Phase change heat transfer, crucial in thermal management systems, can be significantly enhanced through optimized surface structures. This study investigates pool boiling heat transfer enhancement using 3D printed structures with carefully designed pillar and pit geometries. We present a novel approach combining the Dual Rise model with separate liquid–vapor pathways to improve Critical Heat Flux (CHF) and Heat Transfer Coefficients (HTC). Using copper-infused Polylactic Acid (PLA) filaments, we created and sintered structured surfaces featuring pit-assisted nucleation sites, interpillar spacing for vapor escape, and pillar roughness for enhanced liquid supply. Experiments with deionized water and ethanol under atmospheric pressure demonstrated substantial improvements over plain surfaces: water showed an 87% increase in CHF and 39% in maximum HTC, while ethanol exhibited even greater enhancements of 122% in CHF and 61% in HTC. These improvements are attributed to the synergistic effects of optimized surface geometry and separated liquid–vapor pathways, reducing counterflow resistance and improving hydrodynamic stability. A theoretical framework based on the Dual Rise model explains these enhancements, providing insights into coupled capillary action and hemiwicking effects in boiling heat transfer. The study introduces predictive models for CHF and HTC enhancement, offering valuable tools for future design optimization in applications ranging from electronics cooling to power plant thermal management and advanced heat exchangers.

Multifunctional Microneedle Patch with Diphlorethohydroxycarmalol for Potential Wound Dressing.

Treatment of skin wounds with diverse pathological characteristics presents significant challenges due to the limited specific and efficacy of current wound healing approaches. Microneedle (MN) patches incorporating bioactive and stimulus materials have emerged as a promising strategy to overcome these limitations and integrating bioactive materials with anti-bacterial and anti-inflammatory properties for advanced wound dressing. We isolated diphlorethohydroxycarmalol (DPHC) from Ishige okamurae and assessed its anti-inflammatory and anti-bacterial effects on macrophages and its antibacterial activity against Cutibacterium acnes. Subsequently, we fabricated polylactic acid (PLA) MN patches containing DPHC at various concentrations (0-0.3%) (PDPHC MN patches) and evaluated their mechanical properties and biological effects using in vitro and in vivo models. Our findings demonstrated that DPHC effectively inhibited nitric oxide production in macrophages and exhibited rapid bactericidal activity against C. acnes. The PDPHC MN patches displayed potent antibacterial effects without cytotoxicity. Moreover, in 2,4-Dinitrochlorobenzene-stimulated mouse model, the PDPHC MN patches significantly suppressed inflammatory response and cutaneous lichenification. The results suggest that the PDPHC MN patches holds promise as a multifunctional wound dressing for skin tissue engineering, offering antibacterial properties and anti-inflammatory properties to promote wound healing process.

Effects of Ultrasonic Vibration on 3D Printing of Polylactic Acid/Akermanite Nanocomposite Scaffolds

The mechanical properties of 3D-printed scaffolds for load-bearing implantation are crucial. Although the addition of nanoparticles to polymeric matrix scaffolds can improve their mechanical and biological properties, due to certain limitations in printability, high amounts of reinforcement cannot be used. Therefore, in this study, an attempt was made to use ultrasonic (UT) vibration to inhibit nozzle clogging during fused filament fabrication (FFF) of polylactic acid (PLA) scaffolds including 0, 20, and 40 wt.% Akermanite (Ak). Nozzle clogging happened during the conventional 3D printing of PLA-40wt.%Ak, while that did not occur during UT-assisted 3D printing of PLA-40wt.%Ak. Results of X-ray Diffraction (XRD) analysis and Scanning Electron Microscopy (SEM) indicated that applying ultrasonic (UT) vibration had no negative effect on the phases and morphology of the scaffolds. The results obtained by the compression test indicated that applying UT during 3D-printing resulted in almost 27% increment of elastic modulus and almost 25% increase of the compressive strength of the scaffolds. As the conclusion, this study highlights the effectiveness of ultrasonic-assisted 3D printing in producing nanocomposite scaffolds with significantly higher nanoparticle loadings, as compared to conventional printing methods. By utilizing ultrasonic vibration during the printing process, the study showcases the possibility of overcoming viscosity limitations and optimizing the mechanical performance of scaffolds for various biomedical applications, including bone tissue engineering.

Investigating the mechanical properties and crashworthiness of hybrid PLA/GFRP composites fabricated using FDM-filament winding

The failure and crashworthiness performance of hybrid Polylactide (PLA)/Glass Fiber Reinforced Polymer (GFRP) composite tubes subjected to axial and radial quasistatic compression loads were investigated in the present study. The composite tubes are fabricated using hand lay-up and Fused Deposition Modeling (FDM)-filament winding processes. The crashworthiness performance was studied using parameters such as the peak load, energy absorption, crush load, crushing load efficiency, and specific energy absorption. The highest peak loads from the compression test results in the axial and radial directions are calculated using variations in the filament winding PLA/GFRP (FPG) specimen, whose values were 16130.50 N and 12077.33 N, respectively. The highest mean crush load is found in the material variation with the FPG specimen, which is 5734.43 J/mm for axial loading and 4886.75 J/mm for radial loading. The highest energy absorption (EA) value is found in the material variation with the FPG specimen, which is 262.18 J for axial direction loading and 94.02 J for radial direction loading. The highest specific energy absorption (SEA) value is found in the material variation with the specimen Filament Winding PLA/GFRP, which is 16.92 J/g for axial loading and 10.98 J/g for radial loading. There are three main types of failure of the composite: matrix cracking, fiber damage, and folding. The study showed that by combining Additive Manufacturing and composite lamination, the hybrid PLA/GFRP specimen outperformed the existing structures.

PH-induced morphological reversible transition from microparticles to vesicles for effective bacteria entrapment

Polymer particles with stimuli-responsive properties offer promising applications in healthcare, chemical reactors, development of artificial cells and organelles, as well as in the entrapment of bacteria. In this study, a novel biocompatible, biodegradable, and pH-responsive diblock copolymer based on polylactide (PLA) and poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) was synthesized via a metal-free one-pot/simultaneous ring-opening polymerization (ROP) and reversible addition-fragmentation chain transfer (RAFT) approach (ROP/RAFT). This copolymer was then employed to produce highly monodisperse microparticles using microfluidics droplet generation technique. Utilizing confocal microscopy imaging, a reversible pH-induced morphological transition from microparticles to vesicle-like structures was observed at pH 5.1. The reversible shift in morphology from microparticles to giant vesicles (Vs) in acidic environments is triggered by the protonation of amino groups of the PDPA block, rendering vesicle surfaces positively charged − an advantageous feature for attracting and engulfing negatively charged bacteria. Initial validation involved electrostatic interactions with negatively charged latex resin beads followed by assessing interaction capabilities with gram-negative bacteria, Escherichia coli (E. coli). Additionally, the reversible morphological transition of microparticles-to-vesicles was employed to study drug release at different pHs. This approach proven to be a promising strategy for targeted drug delivery and bacteria entrapment using smart pH-responsive microparticles.

Process-structure–property study of 3D-printed continuous fiber reinforced composites

3D-printed fiber-reinforced composites hold many advantages compared to conventional composites in terms of individualization, mass customization, design freedom, and tailoring the composite geometry to load-bearing specifications. Among candidate continuous fibers for reinforcement, basalt fibers (BFs) serve as an eco-friendly alternative with excellent physical and thermal properties. However, the applicability of continuous BFs to be used for 3D-printed polymer composites was rarely addressed in existing literature. Especially, the effects of impregnation density during manufacturing and the influence of local fiber distribution on the fracture behavior of BF-reinforced composites remain unclear. In this study, a solution coating process was employed as a fiber pre-treatment to improve the packing density of BF in a polylactide (PLA) matrix. The effects of the resulting fiber volume fraction (8–31 %) and the local fiber distribution on the tensile fracture mechanisms of 3D printed BF/PLA samples are thoroughly analyzed using three-dimensional X-ray tomography. It was found that at a concentration of 3 wt-%, the coating solution uniformly dispersed optimally between the fibers, resulting in improved impregnation densities of the BF in the PLA matrix. Thus, the resulting composite exhibited a tensile strength of 175 MPa and a Young’s modulus of 6.2 GPa, respectively. A viscoelastic constitutive model incorporating damage is used for property prediction within a composite design framework to be applied to 3D-printed BF/PLA structures. The model is validated with experimental data from tensile tests. The obtained results demonstrate the applicability of eco-friendly BF/PLA composites for 3D printing of industrial high-performance applications with an individualized property profile.

Fabrication of highly flame retardancy and impact strength polylactide foams with phosphorus-containing and agricultural waste-derived multifuctional additives

Research on green polymeric foams is crucial for sustainable development. A polylactide (PLA) foam with a bio-based multifunctional flame-retardant additive derived from agricultural waste was developed and evaluated. Various PLA-based foams were prepared using melt extrusion. A PLA foam with 10 phr of trioctyl phosphate (TOP) showed enhanced crystallization ability, desirable impact strength, and excellent flame retardancy. However, TOP presents concerns for health and the environment. Therefore, bio-based flame retardants (BFRs) derived from agricultural waste were used to partially replace TOP and support the environment friendly and sustainable practices of the bio-circular-green (BCG) economic model. The study used a combination of 2.5 phr of pumpkin shell powder (PK) and 7.5 phr of TOP to produce a PLA foam that achieved a UL-94 V-0 rating, indicating excellent flame retardancy. The impact strength of this foam was about 84 % greater than that of neat PLA foam. The successful incorporation of agricultural waste-derived additives in PLA foam could not only contribute to sustainability but also add value to agricultural waste by repurposing it for a useful application.

MOF Nanosheet-Functionalized Poly(lactic acid) Meta-membranes for Long-Term Air Purification and Intelligent Monitoring.

The wide use of conventional polymeric air filters is causing a dramatically increasing accumulation of plastic and microplastic pollution. The development of poly(lactic acid) (PLA) fibrous membranes for efficient air purification is of important significance but frequently challenged by the rapid decay of filtration performance due to the intrinsically poor electret properties of PLA. Here, we propose an electroactivity promotion methodology, involving the one-step synthesis and homogeneous incorporation of high-dielectric ZIF-8 nanosheets (ZIFNSs), to facilitate interfacial polarization and fiber refinement during electrospinning of PLA nanofibers. The preparative electrospun PLA/ZIFNS meta-membranes exhibited an unusual combination of significantly reduced nanofiber diameter (∼462 nm), enhanced surface potential (approaching 10 kV), and increased surface activity and facilitated the formation of electroactive phases. With well-controlled morphological features, the highly electroactive PLA/ZIFNS meta-membranes exhibited exceptional filtration efficiencies for PM2.5 and PM0.3 (99.2 and 96.0%, respectively) even at the highest airflow rate of 85 L/min, in clear contrast to that of its pure PLA counterpart (only 79.3 and 74.6%). Arising from the increased electroactivity and active contact sites, remarkable triboelectric performance and self-charging mechanisms were demonstrated for the PLA/ZIFNS meta-membranes, contributing to long-term efficient PM0.3 filtration (97.5% for over 360 min). Moreover, as triggered by physiological activities like respiration and speaking, the electroactive PLA/ZIFNS meta-membranes enabled real-time monitoring with high sensitivity and specificity. The proposed strategy affords significant promotion of electroactivity and triboelectric performance for PLA nanofibers, which may motivate the development of ecofriendly protective membranes for respiratory healthcare and real-time monitoring.

Dependence of the crystal structure on the d-units amount in semi-crystalline poly(lactic acid)

The study investigates the impact of the d-lactic acid units content on the crystallinity and crystal structure of commercial poly(lactic acid) (PLA) grades, which are copolymers of poly(l-lactic acid) (PLLA) containing a minor amount of d-units. As the d-units content increases, a detectable decrease in crystallinity was observed along with a simultaneous rise in mobile amorphous fraction (MAF) and a reduction in rigid amorphous fraction (RAF). The percentage of d-units was found not to significantly affect RAF thickness, suggesting that the d-units are not completely excluded from the crystals. The inclusion of d-units as defects in the PLA crystal lattice was confirmed by XRD analysis, which disclosed that the crystal phase gets gradually richer of d-units as the crystallization time evolves. FT-IR analysis proved that the incorporation of d-units in the crystal phase is promoted by the formation of local CH3···O=C interactions, similar to those massively active between PLLA and poly(d-lactic acid) (PDLA) in the stereocomplex. The establishment of these interactions leads to a contraction of the interplanar distances and a decrease in the crystal cell volume with increasing the crystallization time and the d-units percentage. In summary, the study proves that for PLA copolymers containing a d-units percentage at least up to about 8 %, d-units are included in the crystal lattice.

Preparation and characterization of Santa Barbara Amorphous-15 particles functionalized with mercaptopropyl groups and of their composites with poly(lactic acid)

Santa Barbara Amorphous-15 (SBA-15) particles functionalized with mercaptopropyl groups (named as SBASH) have been prepared by a synthetic one-pot approach, and then have been incorporated into poly(lactic acid) (PLA), comparing their characteristics with those shown by composites attained with neat SBA-15 (PLASBA). The silica including the mercaptopropyl groups exhibits a certain loss of regularity because of its functionalization, although displays a better interaction with PLA than the pristine SBA-15 particles in the resulting materials. These composites (PLASBASH and PLASBA) also show a thermal stability slightly higher than neat PLA. An important nucleation effect of SBASH silica in the crystallization of PLA has been deduced from cooling experiments as well as from the cold crystallization in heating runs and from the degree of crystallinity reached. Small Angle X-ray Scattering (SAXS) profiles show that the PLA long spacings are rather similar for the different composites and the neat PLA. Thus, crystal size is rather similar in all samples. Microhardness values show an evident effect of reinforcement in all the composites compared with that shown by neat PLA. Nevertheless, the increase in rigidity is smaller in the biobased PLASBASH composites, those containing the modified silica, than in the PLASBA materials with the pristine SBA-15 particles.

Pyrolysis kinetic analysis of molten bioplastics based on the combination of real-time characterization and Guassian deconvolution: Case study of poly(lactic acid) materials.

Pyrolysis remains a promising method for the utilization of biogradable plastics. However, the kinetics and mechanisms of molten polymer pyrolysis are not well understood, and the effect of additives (mainly inorganic nucleating agents) on the reaction pathway has not been widely explored. In this work, we conducted a method using the thermogravimetric analysis-Fourier transform infrared spectrometry (TG-FTIR) combined with a model-fitting method, instead of a traditional method subjectively selecting a reaction model. The FTIR curves provided information for sub-reaction determination, and the detailed parameters were determined using Gaussian deconvolution. The calculation results revealed that the whole process of poly(latic acid) (PLA) pyrolysis is the random nucleation and nuclei growth model. The introduction of inorganic nucleating agents provided nuclei for PLA decomposition, decreasing the initial activation energy (E) from approximately 136 kJ·mol-1 to 88 and 79 kJ·mol-1 at a conversion rate of 0.01. However, the nucleating agent could hinder the generation of nuclei from PLA ontology, which led to the increase of E value after the nucleating agents were occupied.

High-pressure liquid impregnation of barbatimão bark extract into biopolymeric membrane composed of PBS/PLA and Cloisite 20 A blend

Renowned for its medicinal properties, barbatimão bark extract contains bioactive compounds susceptible to degradation, necessitating their safeguarding within a stable matrix for diverse biomedical applications. This study investigates using high-pressure liquid impregnation (HPLI) to load barbatimão extract into biopolymeric membranes at 30, 45, and 60 °C, and 11MPa. HPLI combines the simplicity of direct immersion with improved mass transfer rates under high pressure. Biopolymeric membranes made from poly(butylene succinate) (PBS), poly(lactic acid) (PLA), and Cloisite 20A (C20A) in a 50/45/5 (v/v) composition were created using electrospinning. Comparative analysis with conventional methods, along with evaluation of impregnated membrane properties using SEM, FTIR, and thermogravimetric analysis, demonstrated the effectiveness of HPLI. HPLI yielded markedly higher phenolic compound loadings, peaking at 43.79mg ETA/g membrane at 11MPa and 45 °C over 6h, compared to 25.44mg ETA/g membrane with conventional impregnation at ambient pressure and 45 °C over the same duration.

A new nano approach to prevent tumor growth in the local treatment of glioblastoma: Temozolomide and rutin-loaded hybrid layered composite nanofiber

Total resection of glioblastoma (GB) tumors is nearly impossible, and systemic administration of temozolomide (TMZ) is often inadequate. This study presents a hybrid layered composite nanofiber mesh (LHN) designed for localized treatment in GB tumor bed. The LHN, consisting of polyvinyl alcohol and core-shell polylactic acid layers, was loaded with TMZ and rutin. In vitro analysis revealed that LHN™Z and LHNrutin decelerated epithelial-mesenchymal transition and growth of stem-like cells, while the combination, LHN™Z+rutin, significantly reduced sphere size compared to untreated and LHN™Z-treated cells (P < 0.0001). In an orthotopic C6-induced GB rat model, LHN™Z+rutin therapy demonstrated a more pronounced tumor-reducing effect than LHN™Z alone. Tumor volume, assessed by magnetic resonance imaging, was significantly reduced in LHN™Z+rutin-treated rats compared to untreated controls. Structural changes in tumor mitochondria, reduced membrane potential, and decreased PARP expression indicated the activation of apoptotic pathways in tumor cells, which was further confirmed by a reduction in PHH3, indicating decreased mitotic activity of tumor cells. Additionally, the local application of LHNs in the GB model mitigated aggressive tumor features without causing local tissue inflammation or adverse systemic effects. This was evidenced by a decrease in the angiogenesis marker CD31, the absence of inflammation or necrosis in H&E staining of the cerebellum, increased production of IFN-γ, decreased levels of interleukin (IL)-4 in splenic T cells, and lower serum AST levels. Our findings collectively indicate that LHN™Z+rutin is a promising biocompatible model for the local treatment of GB.

Ultrasonic assisted electrospinning preparation the polylactic acid loading with perillaldehyde biopolymer film with excellent solvent resistance, water-oxygen barrierstability and preservation effect

Ultrasonic assisted electrospinning preparation the polylactic acid loading with perillaldehyde biopolymer film with excellent solvent resistance, water-oxygen barrierstability and preservation effect

Influence of Printing Parameters to optimize mechanical properties in additive manufacturing – A Review

Abstract Additive manufacturing (3D printing) is a revolutionary technology with widespread applications among various industries. It is a cost effective and fast prototyping technology of 20th century, the parts produced by 3D printing are not only used for pre-production samples but also for replacement of functional parts in various applications. Various methods of 3D printing technologies viz., Fused Deposition, Resin printing etc., are available, however Fused Deposition Modelling (FDM) technique is very popular since it is promising and cost effective. There are two major aspects needs to be considered in preparing a sample from 3D printing, i.e., selection of material and printing parameter. With the advancement of material technology from time to time, the efficient and quality products that are produced with this technology. The present study explores the impact of various parameters that affect mechanical properties of 3D printed Polylactic Acid (PLA) in horizontal orientation.

A novel bio-based ferric flame retardant effectively improving the flame retardancy and mechanical properties of polylactic acid

PTDF is prepared by a convenient ionic reaction of phytic acid, terephthalic dihydrazide and iron salts in water. PTDF has high phosphorus and nitrogen content and good thermal stability, which can effectively improve the flame retardancy of PLA. PTFE is an anti-drip agent and is often used to improve the flame retardancy of PLA together with flame retardants. The addition of 4 wt% PTDF and 0.1 wt% PTFE made PLA reach V-0 flame retardant grade from non-flame retardant, and the oxygen index increased from 19.5 % to 24.5 %. With the increase of PTDF content, the performance of PLA improved significantly. The peak heat release rate (PHRR) and THR of PLA/6PTDF composites decrease by 27.4 % and 16.2 %, respectively, and the flame retardant index FRI increase by 232 %, showing excellent flame retardant efficiency. 6 wt% PTDF can increase the crystallinity of PLA by 25.9 %, tensile strength, maximum force required for impact fracture and notch impact strength by 12 %, 37 % and 129 %, respectively, and effectively improve the mechanical properties and toughness of the composite. The bio-based flame-retardant PLA/PTDF composites reported in this paper can be applied to office equipment.

Bio-inspired e-skin with integrated antifouling and comfortable wearing for self-powered motion monitoring and ultra-long-range human-machine interaction

Electronic skin (e-skin) inspired by the sensory function of the skin demonstrates broad application prospects in health, medicine, and human–machine interaction. Herein, we developed a self-powered all-fiber bio-inspired e-skin (AFBI E-skin) that integrated functions of antifouling, antibacterial properties, biocompatibility and breathability. AFBI E-skin was composed of three layers of electrospun nanofibrous films. The superhydrophobic outer layer Poly(vinylidene fluoride)-silica nanofibrous films (PVDF-SiO2 NFs) possessed antifouling properties against common liquids in daily life and resisted bacterial adhesion. The polyaniline nanofibrous films (PANI NFs) were used as the electrode layer, and it had strong “static” antibacterial capability. Meanwhile, the inner layer Polylactic acid nanofibrous films (PLA NFs) served as a biocompatible substrate. Based on the triboelectric nanogenerator principle, AFBI E-skin not only enabled self-powered sensing but also utilized the generated electrical stimulation for “dynamic” antibacterial. The “dynamic-static” synergistic antibacterial strategy greatly enhanced the antibacterial effect. AFBI E-skin could be used for self-powered motion monitoring to obtain a stable signal output even when water was splashed on its surface. Finally, based on AFBI E-skin, we constructed an ultra-long-range human-machine interaction control system, enabling synchronized hand gestures between human hand and robotic hand in any internet-covered area worldwide theoretically. AFBI E-skin exhibited vast application potential in fields like smart wearable electronics and intelligent robotics.

Ultrasonic Surface Wave Transducers Made of Piezoelectric Polylactic Acid for Structural Health Monitoring

Ultrasonic Surface Wave Transducers Made of Piezoelectric Polylactic Acid for Structural Health Monitoring