Poly Lactic Acid Research Articles

Development and characterization of PLA nanocomposites reinforced with bio-ceramic particles for orthognathic implants: Enhanced mechanical and biological properties

The clinical application of osteofixation materials is crucial for maxillofacial reconstruction and orthognathic surgeries. To overcome the limitations of traditional metallic implants, bioabsorbable materials are gaining popularity due to their ability to avoid secondary removal surgeries and reduce stress shielding. This study investigates third-generation biomaterials, focusing on polylactic acid (PLA) for its biocompatibility and biodegradability, and hydroxyapatite (HAP) for its bioactive osteoconductive and bioresorbable properties. Eggshell nanoparticles (ES-NP), HAP, and bioinert alumina particles coated with titanium dioxide (TiO2@Al2O3) were prepared using ball milling, co-precipitation, and sol-gel methods, respectively. PLA-based nanocomposites PLA/ESNP/Al2O3 (PEA), PLA/HAP/Al2O3 (PHA), PLA/ESNP/TiO2@Al2O3 (PEAT), and PLA/HAP/TiO2@Al2O3 (PHAT) were fabricated via solvent casting. Characterization techniques including X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Field-Emission Scanning Electron Microscopy (FE-SEM) were used to analyze the developed nanoparticles and composites. Results indicated PEAT and PHAT composites exhibited tensile strengths of 33.59 ± 0.38 MPa and 32.46 ± 0.46 MPa, tensile moduli of 1756.17 ± 95.43 MPa and 2367.21 ± 158.84 MPa, and shore d hardness values of 84.10 ± 1.45 SHN and 78.00 ± 2.25 SHN, respectively. Both composites achieved a wettability angle of ∼65° and surface roughness below 2.19 μm, enhancing osteoblast adhesion. Additionally, MG63 cell viability was approximately 80 %, and hemolysis rates were below 2.17 %, demonstrating their potential for maxillofacial implant applications.

Investigation of mechanical properties in FFF- produced PLA samples using the Erichsen test: application of definitive screening and RSM

Purpose This study aims to investigate how printing parameters affect the mechanical properties of specimens produced through fused filament fabrication, using the Erichsen test to assess deformation characteristics and material durability under stress. Design/methodology/approach Polylactic acid (PLA) specimens were printed and tested in accordance with the ISO 20482 standard. Definitive screening was conducted to identify the most influential process parameters. This study examined the effects of four key process parameters – number of layers, layer height, crossing angle and nozzle diameter – on force, distension, peak energy and energy to break. Each parameter was assessed at three levels and a large number of required experiments was managed by using response surface methodology (RSM). Findings This study revealed that the number of layers, layer height and crossing angle are the most significant factors that influence the mechanical properties of 3D-printed materials. The number of layers had the greatest impact on the peak force, contributing 44.25%, with thicker layers typically enhancing material strength. The layer height has a significant effect on energy absorption and deformation, with greater layer heights generally improving these properties. Nozzle diameter contributed only 1.10%, making it the least influential factor; however, its impact became more pronounced in interactions with other parameters. Originality/value This paper presents a comprehensive experimental investigation into the effects of process parameters on the crack strength and behavior of 3D-printed PLA specimens using the RSM method. The documented results can be used to develop optimization models aimed at achieving desired mechanical properties with reduced variation and uncertainty in the final product.

Characterisation of Miswak (Salvadora persica) Fibre-reinforced Polylactic Acid Composites Prepared by Twin Screw Extrusion

Processing of polymer composites employing fibres from sustainable sources as reinforcement has drastically grown in recent years. This research used Miswak fibres (MF) and polylactic acid (PLA) as the main materials for composite processing. Natural fibres typically include a hydroxyl group (-OH), which makes them hydrophilic. In contrast, the hydrophobic nature of polymer matrices causes them to naturally repel water. This problem was resolved by chemically altering the surface of natural fibres using a 2 wt% sodium hydroxide (NaOH) solution. In this paper, the effect of alkaline treatment has been proven by performing chemical analysis, tensile properties, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to analyse the influence of treated MF content on composite characteristics. The results revealed that biocomposites with modified miswak fibres exhibited better properties than untreated miswak fibres-reinforced polymer biocomposites. Treated MF/PLA composites showed an increase in tensile strength of 52.9% and tensile modulus of 8.16%. From the chemical composition test, lignin composition was reduced from 5.09% to 3.06% and hemicellulose from 28.12 to 10.62% after MF was treated. Meanwhile, thermal properties for both TGA and DSC revealed the elimination of hemicellulose and lignin characteristic peaks, improving the thermal stability of the treated MF/PLA composite. Thus, compared to a pristine sample, the resultant composites' higher mechanical strength and thermal stability demonstrated the significance of chemically treated natural fibres. The novelty of this research is the data on miswak fibre treatment, as no research has been found for this selected treated fibre.

Potassium Carbonate as a Low-Cost and Highly Active Solid Base Catalyst for Low-Temperature Methanolysis of Polycarbonate.

As the demand for polycarbonate (PC) plastic increases over the years, the development of a chemical recycling system to produce virgin-like-quality monomers is indispensable not only to attain completely sustainable cycles but also to contribute to the decrease in global plastic pollution. Herein, potassium carbonate (K2CO3) was used as a low-cost, readily available, and highly active solid base catalyst for low-temperature PC methanolysis in the presence of THF as a solvent, producing highly pure and crystalline bisphenol A (BPA) and with a catalytic performance higher than group IIA metal oxides (MgO, CaO, and SrO) and some group IA metal carbonates (NaHCO3, KHCO3, and Na2CO3). THF was the best solvent in aiding the reaction owing to it having a similar polar parameter (δp) to that of PC according to Hansen solubility parameters. By the reaction over the catalyst, 100% PC conversion, 97% BPA yield, and 86% dimethyl carbonate yield were achieved within just 20 min at 60 °C. The catalyst possessed an apparent activation energy (Ea) of 52.3 kJ mol-1, which is the lowest value so far for heterogeneous catalysts, while the mechanistic study revealed that the reaction proceeded via the methoxide pathway. The reusability test demonstrated that the catalyst was reusable at least four times. Furthermore, this catalytic system was successfully applied to actual post-consumerPC wastes and polyesters, including polyethylene terephthalate (PET) and polylactic acid (PLA).

Optimizing ironing parameters in material extrusion (MEX) technology: enhancing efficiency and performance

This study explores the optimization of ironing parameters in Material Extrusion (MEX) technology, specifically targeting improvements in the mechanical properties of polylactic acid (PLA) printed objects, with a focus on enhancing Ultimate Tensile Strength (UTS) and minimizing printing time. To achieve this, we employed a systematic experimental approach that varied flow rate, path speed, and spacing between passes, followed by a comprehensive statistical analysis using Analysis of Variance (ANOVA). Our findings indicate that path speed and spacing between passes significantly influence both UTS and printing time, while flow rate has a minor effect within the tested range. Optimal parameters were determined to be a flow rate of 14.34%, path speed of 30 mm/s, and spacing between passes of 0.3 mm, achieving a composite desirability of 0.970537. Validation using the response optimizer feature in Minitab software confirmed a strong correlation between predicted and experimental results. This research provides practical insights for optimizing MEX parameters, contributing to enhanced mechanical properties and efficiency in additive manufacturing processes.

Aluminate-activated nano-SiO2 for enhancing water vapor barrier properties in polymers films: A safe and effective strategy

In this work, a series of nanocomposite films composed of polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT), polybutylene succinate (PBS), nano-SiO2 activated by aluminate for different times were developed to enhance water vapor barrier properties. The physiochemical and thermal properties of the films were characterized. In addition, total and aluminum migration from the films was monitored, and non-targeted screening was performed to evaluate the potential safety of the composite films. Fourier Transform infrared spectroscopy analysis indicated that the nano-SiO2 was successfully activated by aluminate. Differential scanning calorimetry analysis indicated that incorporation of the activated nano-SiO2 slightly reduced the glass transition temperature (from 54 to 51 °C) and increased the crystallinity degree (from 6.9 % to 11.1 %) of PLA. Incorporation of 0.4 % nanofillers was found to give the highest crystallinity. Thermogravimetric analysis showed that the thermal stability of the PLA/PBAT/PBS films did not change significantly after adding the activated-nano-SiO2. However, the incorporation of these nanofillers did increase the interfacial roughness and crystallinity degree of the films, thereby reducing the water vapor permeability by around 30 %. Erucamide was detected in the composite films after exposure to food simulants, however, the films containing the nanofillers still met European Union safety standards. In summary, the nanofiller-loaded polymer films developed in this study were shown to be safe and have high water barrier properties, which means they may be suitable for application in the food, cosmetic, personal care, pharmaceutical, and agrochemical industries.

Long-short-term memory (LSTM)-based modeling of the stiffness of 3D-printed PLA parts

This study applied a computationally efficient Taguchi-based long-short-term memory (LSTM) algorithm to predict the elastic modulus of 3D-printed polylactic acid (PLA) specimens. 128 data points were collected from the literature, and 80% were allocated for training and the rest for the validation of the LSTM algorithm. The results suggested that the LSTM algorithm, configured with 25 units in the first memory cell, 100 units in the second memory cell, the “selu” activation function in the first memory cell, the “elu” activation function in the second memory cell, the RMSprop optimizer, and a learning rate of 0.01, was precisely able to predict the elastic modulus of 3D-printed PLA parts.

Mechanical Properties of 3D Printed PLA Scaffolds for Bone Regeneration

Abstract The growing interest in biodegradable scaffolds for bone regeneration created a need to investigate new materials suitable for scaffold formation. Poly(lactic acid) (PLA) is a polymer commonly used in biomedical engineering, e.g. in tissue engineering as a biodegradable material. However, the mechanical behavior of PLA along its degradation time is still not explored well. For this reason, the mechanical properties of PLA scaffolds affected by incubation in physiological medium needs to be investigated to show the potential of PLA to be used as a material for biodegradable scaffold formation. The purpose of this research is to determine the mechanical properties of PLA scaffolds before and after incubation, and to apply constitutive material models for further behavior prediction. Two sets of PLA scaffolds were printed by the 3D printer “Prusa i3 MK3S” and sterilized by ultraviolet light and ethanol solution. The first set of specimens was incubated in DMEM (Dulbecco’s Modified Eagle Medium) for 60, 120, and 180 days maintaining 36.5 °C temperature. The mechanical properties of the scaffolds were determined after performing the compression test in the “Mecmesin MultiTest 2.5-i” testing stand with a force applied at two different speed modes. The obtained data was curve fitted with the hyperelastic material models for a model suitability study. The second set of specimens was incubated in PBS (Phosphate Buffered Saline) for 20 weeks and used in a polymer degradation study. The obtained results show that the mechanical properties of PLA scaffolds do not decrease during incubation in physiological medium for a predicted new bone tissue formation period, though hydrolysis starts at the very beginning and increases with time. PLA as a material seems to be suitable for the use in bone tissue engineering as it allows to form biocompatible and biodegradable scaffolds with high mechanical strength, required for effective tissue formation.

Evaluation of polylactic acid polymer composites strengthened with chopped vetiver fiber and pearl millet-derived- nano silica towards environmental sustainability

Evaluation of polylactic acid polymer composites strengthened with chopped vetiver fiber and pearl millet-derived- nano silica towards environmental sustainability

Production of L-lactic acid from methanol by engineered yeast Pichia pastoris

Lactic acid (LA) serves as a widely used platform compound and has received significant attention as a raw material for synthesis of biodegradable polylactic acid. Currently, LA is mainly produced through microbial fermentation, but its high costs undermine its competitive advantage against other materials, necessitating the development of novel production routes. Methanol bioconversion represents an emerging low-carbon circular economy, where LA could become an outstanding representative product. This study successfully established an efficient methanol-based LA synthesis route in Pichia pastoris. Through systematic metabolic engineering strategies, including screening lactate dehydrogenase, modification of cofactor preference, blocking LA consumption pathway, and mitochondrial LA synthesis compartmentalization, 4.2 g/L L-LA was produced in fed-batch fermentation by using methanol as the sole carbon source. Through multi-dimensional and spatial engineering of enzyme, a cell factory was developed for efficient synthesis of L-LA, highlights the significant potential of the low-carbon synthesis route for L-LA via methanol bioconversion.

Heat‐Treatment and Water Immersion Effect on the Mechanical Properties and Joint Strength of 3D‐Printed Polylactic Acid Parts

ABSTRACTThis paper investigates the effect of short‐time water immersion (WI) and heat‐treatment (HT) post‐processes on the mechanical properties and joint strength of printed polylactic acid (PLA) parts with various raster angles. Using these post‐processing methods to enhance the joint strength of printed PLA parts could be deemed as the novelty and the contribution of the current study. The WI and HT of the tensile test specimens and the adherends of the bonded joints were carried out at 21°C and 90°C, respectively. Depending on the raster angle, the tensile strength of the heat‐treated specimens was about 11%–43% higher than that of the untreated specimens. Interestingly, it was found that WI had a more significant effect on the strength of printed parts than HT. In the case of WI, the tensile strength was increased by about 27%–57% as compared to the untreated specimens. Joint tests revealed that HT and WI exerted a similar positive effect on the strength of the joints. The findings highlighted that short‐time WI is at least as effective as HT in increasing the tensile and joint strengths of 3D‐printed PLA parts.

An innovative multilayered material fabricated through additive manufacturing for structural applications: method and mechanical properties

Abstract Additive manufacturing (AM) is a cost-effective method for fabricating structurally sound components. Fused filament fabrication (FFF) is a popular AM technique known for its design flexibility, minimal material wastage, and recyclability. Poly lactic acid (PLA) is a thermoplastic widely used in aerospace, biomedical, and automobile industries. Wood-PLA, incorporating wood fillers into PLA, finds applications in several industries. This research explores multilayered materials (MLM) for enhanced performance in various sectors such as aircraft, energy, and biomedical. Mechanical properties of MLM were investigated under different load conditions (tensile, bend, compressive). Properties simulated through Finite Element Method (FEM) showed minimal error (less than 1 %). Microscopic analysis, aided by scanning electron microscope (SEM) fractography, reveals a brittle mode of failure in the specimens. This study provides valuable insights into the mechanical behaviour of MLM, offering potential applications in diverse industries.

Improvement of Thermal Stability of Charges in Polylactic Acid Electret Films for Biodegradable Electromechanical Sensors.

Eco-friendly sensors fabricated from biocompatible and biodegradable materials are promising candidates for wearable and implantable electronics due to their environmental sustainability and biosafety. This article reports a fully biodegradable electromechanical sensor (FBES) utilizing a sandwich structure with macro ripple structured polylactic acid (PLA) electret films acting as sensitive layers and molybdenum (Mo) sheets serving as electrodes for a wearable device application. The stability of the space charge stored within the PLA film has been enhanced by introducing an internal cellular structure and improving the polarization process. A macro ripple structure of the PLA layer with higher deformation is a great guarantee for boosting the pressure sensitivity. The results indicate that inserting cell microstructures and optimizing the polarization process significantly improve the charge storage stability of PLA films by nearly 55%. This enhancement is attributed to several factors, including the extended charge drift path of the charges in cellular films, a synergy effect of surface charges, and "macroscopic" dipole charges distributed in the cells. The fabricated sensor achieves a high sensitivity of 1000 pC/kPa, a wide pressure detection range of 0.03-62.4 kPa, and satisfactory stability. Such sensors are not only sensitive to body movements but also to subtle physiological signals, satisfying the diverse needs of wearable healthcare. Importantly, all the composition materials of the sensor can be completely degraded after their service, aligning with the environmentally friendly principles of green development.

Optimization of Barrier Properties of PLA/PBAT Polymers in Biodegradable Materials

AbstractDespite its popularity as a bio‐based biodegradable material, polylactic acid (PLA) has a number of shortcomings. Nevertheless, the combination of poly(butylene adipate co‐terephthalate) (PBAT) and thermoplastic starch (TPS) to enhance the mechanical properties of PLA was achieved through the utilisation of PLA/PBAT/TPS ternary composites, which were created through the calendering method. These composites exhibit advantageous characteristics, including high ductility, enhanced toughness, and biodegradability. The results of the water vapour permeability test indicate that the proportion of the material composition exhibiting the lowest value of water vapour permeability is 2.0571 g/m²·24h. The results of the water vapour transmission test demonstrate that the material generated by the composition ratio has the lowest water vapour transmission, indicating that the composite material blending effect is superior. The majority of current research employs nanocellulose as a substrate in PLA, with a paucity of studies investigating its use in PLA/PBAT/TPS composites. These composites are modified due to the notable divergence of nanocellulose from the hydrophobicity of the composite and its susceptibility to decomposition at elevated temperatures. This study establishes a foundation for future research in this field.

Enhanced Impact Resistance, Oxygen Barrier, and Thermal Dimensional Stability of Biaxially Processed Miscible Poly(Lactic Acid)/Poly(Butylene Succinate) Thin Films

This study investigates the crystallization, microstructure, and performance of poly(lactic acid)/poly(butylene succinate) (PLA/PBS) thin films processed through blown film extrusion and biaxial orientation (BO) at various blend ratios. Succinic anhydride (SA) was used to enhance interfacial adhesion in PLA-rich blends, while blends near 50/50 formed co-continuous phases without SA. Biaxial stretching and annealing, adjusted according to the crystallization behavior of PLA and PBS, significantly influenced crystallinity, crystallite size, and molecular orientation. Biaxial stretching induced crystallization and ordered chain alignment, particularly at the cold crystallization temperature (Tcc), leading to a 70–80-fold increase in impact resistance compared to blown films. Annealing further enhanced crystallinity, especially at the Tcc of PLA, resulting in larger crystallite sizes. BO films demonstrated reduced thermal shrinkage due to improved PLA crystalline structure, whereas PLA-rich blown films showed higher shrinkage due to PLA’s lower thermal resistance. The SA-miscibilized phase reduced oxygen transmission in blown films, while BO films exhibited higher permeability due to anisotropic crystal orientation. However, the annealing of BO films, especially at high temperature (Tcc of PLA), further lowered oxygen permeability by promoting the crystallization of both PLA and PBS phases. Overall, the combination of SA compatibilization, biaxial stretching, and annealing resulted in substantial improvements in mechanical strength, dimensional stability, and oxygen barrier properties, highlighting the potential of these films for packaging applications.

Key Advances in Solution Blow Spinning of Polylactic-Acid-Based Materials: A Prospective Study on Uses and Future Applications

Solution blow spinning (SBS) is a versatile and cost-effective technique for producing nanofibrous materials. It is based on the principles of other spinning methods as electrospinning (ES), which creates very thin and fine fibers with controlled morphologies. Polylactic acid (PLA), a biodegradable and biocompatible polymer derived from renewable resources, is widely used in biomedical fields, environmental protection, and packaging. This review provides a theoretical background for PLA, focusing on its properties that are associated with structural characteristics, such as crystallinity and thermal behavior. It also discusses various methods for producing fibrous materials, with particular emphasis on ES and SBS and on describing in more detail the main properties of the SBS method, along with its processing conditions and potential applications. Additionally, this review examines the properties of nanofibrous materials, particularly PLA-based nanofibers, and the new applications for which it is thought that they may be more useful, such as drug delivery systems, wound healing, tissue engineering, and food packaging. Ultimately, this review highlights the potential of the SBS method and PLA-based nanofibers in various new applications and suggests future research directions to address existing challenges and further enhance the SBS method and the quality of fibrous materials.

Recent Advance of Sustainable Polymers for Packaging Applications

The extensive application of non-renewable polymers has brought about deep environmental concerns, demonstrating the immediate requirement for new biodegradable and biobased packaging choices. The work offers an in-depth look at a wide array of degradable and biobased polymers like Polylactic Acid (PLA), Polyhydroxyalkanoates (PHA), and Polyvinyl Alcohol (PVOH), as well as starch and cellulose materials, discussing their qualities, uses, and the issues faced in food packaging. These types of green polymers, either in new ways or from renewable sources, offer great advances not only from decomposition into harmless parts but also from the reduction of environmental damage. The essay covers the exploitation side of this material, be it the role of PLA in enzymatic, hydrolytic, or microbial degradations, or the main tactical function of PHA in terms of a water barrier aimed at preserving the quality of stored food. Additionally, the multifunctionality of these substances is represented anew in packaging dairy goods, such as fruits, and vegetables, and specialized applications like edible films or water-soluble bags. The participation of compostable polymers has become increasingly vital in the area of food packaging to meet consumers’ demands and to upgrade the present science technologies aimed at guiding food producers who are looking for more sustainability in their business.

Highly Porous 3D Nanofibrous Scaffold of Polylactic Acid/Polyethylene Glycol/Calcium Phosphate for Bone Regeneration by a Two-Step Solution Blow Spinning (SBS) Facile Route

This work presents the successful production of highly porous 3D nanofibrous hybrid scaffolds of polylactic acid (PLA)/polyethylene glycol (PEG) blends with the incorporation of calcium phosphate (CaP) bioceramics by a facile two-step process using the solution blow spinning (SBS) technique. CaP nanofibers were obtained at two calcium/phosphorus (Ca/P) ratios, 1.67 and 1.1, by SBS and calcination at 1000 °C. They were incorporated in PLA/PEG blends by SBS at 10 and 20 wt% to form 3D hybrid cotton-wool-like scaffolds. Morphological analysis showed that the fibrous scaffolds obtained had a randomly interconnected and highly porous structure. Also, the mean fiber diameter ranged from 408 ± 141 nm to 893 ± 496 nm. Apatite deposited considerably within 14 days in a simulated body fluid (SBF) test for hybrid scaffolds containing a mix of hydroxyapatite (HAp) and tri-calcium phosphate-β (β-TCP) phases. The scaffolds with 20 wt% CaP and a Ca/P ration of 1.1 showed better in vitro bioactivity to induce calcium mineralization for bone regeneration. Cellular tests evidenced that the developed scaffolds can support the osteogenic differentiation and proliferation of pre-osteoblastic MC3T3-E1 cells into mature osteoblasts. The results showed that the developed 3D scaffolds have potential applications for bone tissue engineering.

Biocompatible PVAc-g-PLLA Acrylate Polymers for DLP 3D Printing with Tunable Mechanical Properties.

The technological advancement of Additive Manufacturing has enabled the fabrication of various customized artifacts and devices, which has prompted a huge demand for multimaterials that can cater to stringent mechanical, chemical, and other functional property requirements. Photocurable formulations that are widely used for Digital Light Processing (DLP)/Stereolithography (SLA) 3D printing applications are now expected to meet these new challenges of hard and soft or stretchable structural requirements in addition to good resolution in multiple scales. Here we present a biocompatible photocurable resin formulation with tunable mechanical properties that can produce hard or stretchable elastomeric 3D printed materials in a graded manner. Acrylate poly(lactic acid) (PLA) grafted polyvinyl acetate (PVAc) polymer was mixed with hydroxyl ethyl methacrylate (HEMA) and hydroxyl ethyl acrylate (HEA) as reactive diluents (50-70 wt %) in various compositions to form a series of photocurable resin formulations. Depending on the nature of the reactive diluent (HEMA or HEA) and their weight percentage, the mechanical properties of the 3D printed parts could be fine-tuned from hard (Tensile strength 20.6 ± 2 MPa, elongation 2 ± 1%) to soft (Tensile strength 1.1 ± 0.2 MPa, elongation 62 ± 8%) materials. The printed materials displayed remarkable dye absorption (95%), showing stimuli-responsive behavior for dye release (with respect to both pH and enzyme), while also demonstrating high cell viability (>90%) for mouse embryonic (WT-MEF) cells and degradability in PBS solution. These biobased 3D printing resins have the potential for a variety of applications, including tissue engineering, soft robotics, dye absorption, and elastomeric actuators.

Optimizing tribological performance of 3D-printed poly(lactic acid) components through process parameter analysis

Optimizing tribological performance of 3D-printed poly(lactic acid) components through process parameter analysis