Poly Lactic Acid Research Articles

The effects of 3D printing designs on PLA polymer flexural and fatigue strength

This study assessed the comprehensive assessment of flexural and fatigue strength of the three-dimensional (3D)-printed polylactic acid (PLA) samples across diverse printing designs and parameters. The experiment framework included a diverse array of printing parameters: layer heights, first layer thicknesses, infill densities, top/bottom infill patterns, extruder temperatures, perimeters, and types of solid layer top and bottom. Our findings suggest that there is an interplay between these parameters and the mechanical properties of PLA specimens. Notably, the fatigue strength of PLA printing specimens is more significantly influenced (0.44%) by an increase in the thickness of the first layer compared to flexural strength (87%). The rate of increase in bending strength is lower in cases of layer height (3.55%) and initial layer height (0.44%) in contrast with other factors. Specimens with an initial layer thickness of 0.4 mm reached the highest number of cycles until failure, recording 21 022 cycles. Furthermore, the study identifies the infill pattern’s impact on strength, highlighting that the line infill pattern type case has the highest bending strength of 75.97 MPa and surpasses the honeycomb pattern in bending strength. Compared to the Honeycomb pattern, the rectilinear design has 2.1% higher bending strength. The number of cycles to failure of the rectilinear pattern is greater than those of the honeycomb pattern. In comparison to other patterns, the Rectilinear Top/Bottom infill pattern has a higher interest rate of 27.5% for bending strength and 200.83% for fatigue strength. Additionally, greater bending and flexural strength are obtained by raising the solid layer top, bottom, and perimeter values, respectively. In comparison to the other temperatures, the bending strength and fatigue strength are highest at 200 °C. Therefore, the first layer height of 0.4 mm, the top/bottom rectilinear infill pattern, the extruder temperature of 200 °C, the perimeter value of 3, the solid layer/top value of 3, and the solid layer/bottom value of 3 are the optimal values for the part subjected to at the same time bending strength combined with fatigue strength. This comprehensive study may provide a broader and deeper understanding of individual and combined effects on an overview of the bending and fatigue strength in connection to printing design and printing parameters, as well as the ideal optimal parameters for 3D printing with the PLA material. Manufacturers and designers can use the recommended parameters to optimize the strength of their printed parts, considering both bending and fatigue performance.

Enhancing poly(lactic acid)/maleated polypropylene blend with magnesium oxide catalyst: a reactive blending approach for improved mechanical properties

Some defects of polylactic acid (PLA), especially its poor mechanical properties, were modified using a minimum content of non-biodegradable maleated polypropylene (MAPP). To this end, first, the amount of MAPP was optimized, which was 20 wt.%. Second, MgO was used as a new catalyst to improve the exchange reactions between active groups in both polymers in a reactive blending process. Tensile and izod analyses showed that, compared to neat PLA, with a slight decrease in modulus and tensile strength, elongation at break, and impact resistance were improved in the presence of 20 and 0.1 wt.% of MAPP and MgO, respectively. This improvement in mechanical properties can be related to the exchange reactions between two polymers and the formation of PLA-MAPP block copolymers. MFI and WDCA analyses demonstrated the increase in melt flowability and surface hydrophilicity of the resulting blends, respectively. DSC analysis showed that the Tg values of both polymers approached each other in the presence of catalyst. Also, the elimination of cold crystallization of PLA and the decrease in the Tm and crystallinity of both polymers are clear reasons for the miscibility of the alloy. TEM displayed the proper dispersion of MgO nanoparticles within the polymer matrix, and in addition, the XRD test also proved the decrease in the crystallinity of both polymers and appropriate miscibility of the samples containing 20 and 0.1 wt.% of MAPP and MgO, respectively. These results can promise the design of a compound with the maximum amount of PLA for further use in various industries.

Investigation of Thermomechanical and Dielectric Properties of PLA-CA 3D-Printed Biobased Materials

Renewable dielectric materials have attracted the attention of industries and stakeholders, but such materials possess limited properties. This research focused on studying polylactic acid (PLA)/cellulose acetate (CA) blends produced by 3D printing to facilitate their integration into the electrical insulation field. The dielectric findings showed that a blend containing 40% of CA by weight had a dielectric constant of 2.9 and an electrical conductivity of 1.26 × 10−11 S·cm−1 at 100 Hz and 20 °C while exhibiting better mechanical rigidity in the rubbery state than neat PLA. In addition, it was possible to increase the electrical insulating effect by reducing the infill ratio at the cost of reduced mechanical properties. The differential scanning calorimetry, broadband dielectric spectroscopy, and dynamic mechanical analysis results showed that the PLA plasticizer reduced the energy required for PLA relaxations. These preliminary results demonstrated the benefits of using a combination of PLA, CA, and 3D printing for electrical insulation applications.

Fabrication of 3D micropatterned hydrophobic surfaces by fused filament fabrication printing technology

AbstractIn recent years, the interest in structured hydrophobic surfaces has considerably grown, finding applications in many industrial fields, including aerospace, automotive, and biomedical. Three‐dimensional (3D) printing technology is a simple, rapid and economic process to fabricate structured surfaces based on neat polymers and composite materials, allowing working with a wide variety of plastic materials. The manufactured surfaces show a roughness depending on the printing design and the printing resolution: this characteristic is ideal to achieve superhydrophobic properties. Furthermore, patterned surface structures can be printed by Fused Filament Fabrication (FFF), so increasing the hydrophobic character of the samples; indeed, micro and nano surface structures are required to make a hydrophobic surface.In this study, 3D micro‐patterned textures of pillars were printed by FFF using polylactide (PLA) and polypropilene (PP) as polymer filaments and PLA/carbon nanotubes (PLA/CNT) and PP/carbon fibers (PP/CF) as composite filaments. Morphologies of printed specimens were analyzed by optical microscopy and scanning electron microscopy (SEM). Good correspondence was found between pillars dimensions and edge‐edge pillars distance of CAD model and composites 3D printed samples. Their wettability was evaluated by static contact angle measurements. Results clearly show a significant increase of water contact angle values up to 50% in all micropatterned samples with respect to flat surfaces. This improvement was achieved by surface microstructuring without the use of nanoparticles and/or chemical treatment.This article is protected by copyright. All rights reserved.

Limpet-inspired design and 3D/4D printing of sustainable sandwich panels: Pioneering supreme resiliency, recoverability and repairability

Sandwich panels, characterized by their solid exterior and thick, soft core, find extensive applications ranging from maritime to aerospace sectors due to their exceptional resilience and energy absorption/dissipation capabilities. The natural limpet, known for its resilience to mechanical loading, serves as inspiration in the present research to introduce innovative repairable core shells. Limpet-inspired shells with elasto-plastic and brittle behaviors are designed and 3D/4D printed using polylactic acid (PLA) filaments and resins via fused filament fabrication (FFF) and liquid crystal display (LCD) techniques. While PLA filament exhibits an elasto-plastic response with a shape-recovery feature, the resin results in brittle structures for LCD-printed design. The study demonstrates that the FFF-printed PLA shell can fully recover residual plastic deformations, while the LCD-printed PLA shell exhibits a mechanical fracture behavior very similar to the natural limpet with brittle properties. A nonlinear finite element model (FEM) is also developed to replicate the large deformations of the samples under quasi-static compression with a high level of accuracy. Experimental and numerical results reveal that the samples with material, mechanical behavior, and geometry close to the natural limpet result in the maximum energy dissipation per unit mass. Two bio-inspired cores are then tessellated to introduce a new class of sustainable sandwich panels with supreme recoverability, resiliency, and repairability. A three-point bending test is numerically carried out on sandwich panels using FEM, and their energy absorption and dissipation capacities are studied. Results demonstrate that the proposed sandwich panels can achieve almost 7.33 and 1.17 times higher energy dissipation per unit mass than those developed based on a recycled thermoplastic bottle cap core. This pioneering research sets a new benchmark for structural design in terms of resiliency, recoverability, repairability, and sustainability.

Highly Cytocompatible Polylactic Acid Based Electrospun Microfibers Loaded with Silver Nanoparticles Generated onto Chestnut Shell Lignin for Targeted Antibacterial Activity and Antioxidant Action.

Electrospun (e-spun) fibers are generally regarded as powerful tools for cell growth in tissue regeneration applications, and the possibility of imparting functional properties to these materials represents an increasingly pursued goal. We report herein the preparation of hybrid materials in which an e-spun d,l-polylactic acid matrix, to which chitosan or crystalline nanocellulose was added to improve hydrophilicity, was loaded with different amounts of silver(0) nanoparticles (AgNP) generated onto chestnut shell lignin (CSL) (AgNP@CSL). A solvent-free mechanochemical method was used for efficient (85% of the theoretical value by XRD analysis) Ag(0) production from the reduction of AgNO3 by lignin. For comparison, e-spun fibers containing CSL alone were also prepared. SEM and TEM analyses confirmed the presence of AgNP@CSL (average size 30 nm) on the fibers. Different chemical assays indicated that the AgNP@CSL containing fibers exhibited marked antioxidant properties (EC50 1.6 ± 0.1 mg/mL, DPPH assay), although they were halved with respect to those of the CSL containing fibers, as expected because of the efficient silver ion reduction. All the fibers showed high cytocompatibility toward human mesenchymal stem cells (hMSCs) representative of the self-healing process, and their antibacterial properties were tested against the pathogens Escherichia coli (E. coli), Staphylococcus epidermidis, and Pseudomonas aeruginosa. Finally, competitive surface colonization as simulated by cocultures of hMSC and E. coli showed that AgNP@CSL loaded fibers offered the cells a targeted protection from infection, thus well balancing cytocompatibility and antibacterial properties.

Effect of seed husk waste powder on the PLA medical thread properties fabricated via 3D printer

Abstract With the increasing use of medical equipment, threads are the catchy choice for medical personnel to solve wound closures. One raw material used in medical surgical threads is polylactic acid (PLA), which is appropriate for its environmentally friendly and biodegradable properties. However, the weakness of PLA is in mechanical properties. This work used extrusion-based three-dimensional (3D) printing (fused deposition modeling) to fabricate medical threads from PLA. The effect of adding seed husk waste powders (SHWPs) to PLA filament (1.75 mm) and its manufacture by the 3D printer was studied. Four types of SHWP waste plants were used: pistachio, coffee, chestnuts, and walnuts crushed and milled by ball-milling after chemical processing and drying. The structural, particle size, and physical properties of the prepared powders were studied. The results of SHWPs show that the particle size is near the nano-size range of NPs and of low density. Different SHWP weight mixing ratios (5–15 wt%) were coated to PLA threads (0.4–0.45 µm) by grafting to study the mechanical (surface hardness and roughness) properties. The result shows that 15 wt% was the best ratio that combined the mechanical properties. The coated layer thickness was less than 5 µm. This ratio was adopted to fabricate grafted PLA and SHWPs/PLA medical threads by 3D printing with a radius of 400 ± 5 µm. The structural and biological properties of the fabricated medical threads were investigated. The results of SHWP-coated PLA show a significant improvement in structural and physical properties besides the mechanical properties. The results adopted this percentage from thread SHWP-coated PLA for medical applications, creating a new benefit for agricultural SHW and accelerated healing.

Bioinspired poly-dopamine/nano-hydroxyapatite: an upgrading biocompatible coat for 3D-printed polylactic acid scaffold for bone regeneration.

Poly-lactic acid (PLA) has been proposed in dentistry for several regenerative procedures owing to its biocompatibility and biodegradability. However, the presence of methyl groups renders PLA hydrophobic, making the surface less ideal for cell attachment, and it does not promote tissue regeneration. Upgrading PLA with inductive biomaterial is a crucial step to increase the bioactivity of the PLA and allow cellular adhesion. Our purpose is to evaluate biocompatibility, bioactivity, cellular adhesion, and mechanical properties of 3D-printed PLA scaffold coated with poly-dopamine (PDA) and nano-hydroxyapatite (n-HA) versus PLA and PLA/n-HA scaffolds. The fused deposition modelling technique was used to print PLA, PLA with embedded n-HA particles, and PLA scaffold coated with PDA/n-HA by immersion. After matrices characterization for their chemical composition and surface properties, testing the compressive strength was pursued using a universal testing machine. The bioactivity of scaffolds was evaluated by monitoring the formation of calcium phosphate compounds after simulated body fluid immersion. The PLA/PDA/n-HA scaffold showed the highest compressive strength which was 29.11 ± 7.58 MPa with enhancing calcium phosphate crystals deposition with a specific calcium polyphosphate phase formed exclusively on PLA/PDA/n-HA. With cell viability assay, the PDA/n-HA-coated matrix was biocompatible with increase in the IC50, reaching ⁓176.8 at 72 without cytotoxic effect on the mesenchymal stem cells, promoting their adhesion and proliferation evaluated by confocal microscopy. The study explored the biocompatibility, bioactivity, and the cell adhesion ability of PDA/n-HA coat on a 3D-printed PLA scaffold that qualifies its use as a promising regenerative material.

Multifunctional 3D-printed composites based on biopolymeric matrices and tomato plant (Solanum lycopersicum) waste for contextual fertilizer release and Cu(II) ions removal

The production of tomatoes faces significant challenges, including the high amount of waste generated during the harvest stage and copper-contaminated soil due to pesticide use. To address these issues and to promote a more sustainable agriculture, innovative biodegradable green composites for contextual controlled soil fertilization and Cu removal were produced by 3D-printing technology. These composites were made by incorporating NPK fertilizer flour and tomato plant waste particles (SLP) into three different biodegradable polymeric matrices: polylactic acid (PLA); a commercial blend of biodegradable co-polyesters (Mater-Bi®, MB) and their blend (MB/PLA, 50:50). Rheological characterization suggested the potential processability of all of the composites by FDM. Morphological analysis of printed samples confirmed the good dispersion of both filler and fertilizer, which also acted as reinforcement for MB and MB/PLA composites. SLP and NPK moduli were evaluated by powder nanoindentation and, for almost composites, the theoretical Halpin-Tsai model satisfactorily fitted the actual tensile moduli. The decrease in NPK fertilizer release rate and the increase in Cu(II) removal efficiency were achieved using whole 3D-printed composites. By selecting the appropriate matrix and incorporating SLP particles, it was possible to tune the NPK release rate and achieve copper absorption efficiency. Notably, MB samples containing SLP particles displayed the fastest release and the highest Cu(II) removal efficiency.Graphical abstract

Comparative Study of Electrospinning Parameters for Production of Polylactic Acid and Polycaprolactone Nanofibers Based on Design of Experiment

In terms of applications, the diameter of nanofibers is one of their most important characteristics. This size is influenced by various process parameters, such as: the concentration, the distance between the needle and the collector, volume flow, etc. In this study, we compared the average diameter of nanofibers made from two different polymers, polycaprolactone and polylactic acid.We investigated the impact of various parameters on the production of nanofibers from polycaprolactone and polylactic acid using the electrospinning technique. We employed a factorial experiment design model to characterize this versatile and efficient fibre fabrication method. By considering the effects of voltage, concentration, distance between the pin and the collector, and flow rate, we established a mathematical model to describe the process. The diameters and morphologies of the resulting fibers were analyzed and compared to each other using SEM analysis. Our findings revealed that, among the studied parameters, concentration had the most significant impact on the diameter of the polymer fibers.

Design on thermal-mechanism coordination for binding reinforcing mesh based on shape memory polymer

Abstract The traditional rebar binding devices require complex drive and transmission mechanisms, which leads to large volume and complex structure. In this paper, a cylindrical thermoplastic shape memory polymer (SMP) fixture is proposed to verify the rebar binding method of thermal-mechanism coordination. The SMP fixture is manufactured by the injection molding technology through selecting suitable-ratio Polylactic acid (PLA) and Polycaprolactone (PCL) blend materials. Besides, an additional auxiliary device is presented to overcome the incomplete recovery disadvantage existing in the thermoplastic SMP and completely achieve binding the rebar. On this base, two different binding methods are proposed to compare the mechanical performance after fixing the rebar, and the external force/thermal contributions are tested and discussed in detail. The tested results show that the binding contribution of heat could reach 70% while the binding contribution of external force could reach 30% above the transition temperature (Tg). The maximum tensile force that the binding rebar can withstand under the thermal-mechanism coordination action could reach up to 657.7 N, which is higher than the maximum tensile force of the wire binding. In addition, the maximum friction force between rebar and notches of fixture could reach up to 94.1 N, which further verifies the feasibility of thermal-mechanism coordination for binding reinforcing mesh based on SMP fixture.

Coupled engineering strategy of CYB2 deletion and ACS1 overexpression improves cellulosic lactic acid production by Saccharomyces cerevisiae

Lactic acid plays a significant role in the food industry as a natural preservative and serves as a platform chemical for the production of biodegradable poly-lactic acid. While its sustainable production through fermentation using cellulosic biomass instead of traditional sugar and starch raw materials shows promise, there remains limited information available on this method. In this study, a xylose-fermenting and lactic acid-tolerant Saccharomyces cerevisiae strain (BK01) was engineered for improved cellulosic lactic acid production using the promising energy crop, kenaf. Specifically, CYB2 was deleted to inhibit lactic acid consumption (BK02), which was further engineered by ACS1 overexpression to remove the cytotoxic acetate derived from cellulosic biomass (BK03). The BK03 produced 3.25-fold more lactic acid from kenaf pulp hydrolysate than the parental strain (BK01). During pH-controlled fermentation, lactic acid production by BK03 reached a titer of 31 g/L and a productivity of 1.30 g/L-h, the highest value reported so far. This is one of the few studies on yeast-based lactic acid production from lignocellulose.

The impacts of biodegradable and non-biodegradable microplastic on the performance and microbial community characterization of aerobic granular sludge

IntroductionMicroplastics (MPs), identified as emerging contaminants, have been detected across diverse environmental media. Their enduring presence and small size facilitate the adsorption of organic pollutants and heavy metals, leading to combined pollution effects. MPs also accumulate in the food chain thus pose risks to animals, plants, and human health, garnering significant scholarly attention in recent years. Aerobic granular sludge (AGS) technology emerges as an innovative approach to wastewater treatment. However, the impacts of MPs on the operational efficiency and microbial characteristics of AGS systems has been insufficiently explored.MethodsThis study investigated the effects of varying concentration (10, 50, and 100 mg/L) of biodegradable MPs (Polylactic Acid, PLA) and non-biodegradable MPs (Polyethylene Terephthalate, PET) on the properties of AGS and explored the underlying mechanisms.Results and discussionsIt was discovered that low and medium concentration of MPs (10 and 50 mg/L) showed no significant effects on COD removal by AGS, but high concentration (100 mg/L) of MPs markedly diminished the ability to remove COD of AGS, by blocking most of the nutrient transport channels of AGS. However, both PLA and PE promoted the nitrogen and phosphorus removal ability of AGS, and significantly increased the removal efficiency of total inorganic nitrogen (TIN) and total phosphorus (TP) at stages II and III (P < 0.05). High concentration of MPs inhibited the growth of sludge. PET noticeably deteriorate the sedimentation performance of AGS, while 50 mg/L PLA proved to be beneficial to sludge sedimentation at stage II. The addition of MPs promoted the abundance of Candidatus_Competibacter and Acinetobacter in AGS, thereby promoting the phosphorus removal capacity of AGS. Both 50 mg/L PET and 100 mg/L PLA caused large amount of white Thiothrix filamentous bacteria forming on the surface of AGS, leading to deterioration of the sludge settling performance and affecting the normal operation of the reactor. Comparing with PET, AGS proved to be more resistant to PLA, so more attention should be paid to the effect of non-biodegradable MPs on AGS in the future.

Experimental investigation of the polymer-metal hybrids interfacial bonding fabricated by fused deposition modeling

In this paper, the fabrication of polymer-metal hybrids by fused deposition modeling was evaluated. 6061 aluminum alloy and polylactic acid were used in the manufacturing process. Also, to strengthen the bonding between the metal and polymer components, a two-component epoxy adhesive was used. The pull-off adhesion test was performed to evaluate the interfacial bonding strength of the specimens. In this study, the effect of bed temperature, print speed, printer nozzle diameter, and aluminum sheet surface roughness on the bond strength of polymer-metal hybrids has been investigated. The results showed that increasing the bed temperature, and aluminum sheet surface roughness, and also decreasing the print speed led to increase the bond strength of polymer-metal hybrids. Finally, by using the experimental data, an optimal specimen was produced. The interfacial bonding strength of the optimal specimen is about 64% stronger than the initial specimen.

Exploring the Potential of Sustainable Biopolymers as a Shield against Electromagnetic Radiations.

The increasing demand for biodegradable and environmentally friendly materials is shifting the focus from traditional polymer composites to biocomposites in various applications, especially in electromagnetic shielding. Effective utilization of biopolymers demands improved properties and can be achieved to a certain extent by functionalization. Biopolymers such as cellulose, polylactic acid, and starch are some of the potential candidates for mitigating electromagnetic pollution in next-generation electronic devices because of their high aspect ratio, flexibility, light weight, high mechanical strength, thermal stability, and tunable microwave absorption to the electromagnetic interference (EMI) shielding composites. This Review provides an overview of the current advancements in EMI shielding materials and outlines recent research on EMI shielding composites that utilize various biodegradable polymer structures.

Sustainable improvement in the polylactic acid properties of 3D printing filaments: The role of bamboo fiber and epoxidized soybean oil‐branched cardanol ether compatibilizer

AbstractPolylactic acid (PLA) is the prevailing raw material for fused deposition modeling (FDM) 3D printing filaments, offering benefits such as a low printing temperature, minimal shrinkage, and biodegradability. However, this material has challenges such as poor toughness, low heat deflection temperature, susceptibility to moisture‐induced thermal degradation, and high costs. This study addressed these concerns by incorporating natural bamboo fiber (BF) into PLA, elevating heat the deflection temperature and lowering the material costs. Additionally, a synthesized branched structure compatibilizer, in the form of epoxidized soybean oil‐branched cardanol ether (ESOn‐ECD), enhanced the toughness of PLA, the bonding strength between PLA and the BF surface, and the flowability of high‐fiber composites during processing and printing. The mechanical, thermal, and rheological properties were assessed, demonstrating the promising processing performance of PLA/BF/ESO3‐ECD. The fully biobased composite exhibits strength, toughness, good processability, excellent 3D printability, and durability, implying substantial potential in FDM 3D filament production.Highlights Bio‐based PLA/bamboo fiber/ESO3‐ECD FDM 3D printing filaments were developed. The excellent nucleation ability of the bamboo fibers enhances the crystallization rate and crystallinity of PLA. The epoxy values and branching degree of ESOn‐ECD are crucial for its effective modification.

Novel catalyst-solvent system for high molecular weight polylactic acid synthesis via azeotropic solution polycondensation method

ABSTRACT Polycondensation for PLA synthesis is widely used due to its cost-effectiveness, but it often leads to low molecular weight PLA. To address this limitation, researchers have explored different catalysts, with the stannous chloride and p-toluene sulfonic acid combination being a popular choice. However, this method typically yields PLA with a MW of no more than 35000 g/mol, which is unsuitable for commercial applications. In contrast, ring-opening polymerization is considered the most effective method for synthesizing high MW PLA, despite its complexity and cost. Industrial-scale production predominantly employs ROP due to its capability to produce high MW PLA. The use of stannous octoate as a catalyst for ROP has shown promise in synthesizing higher MW PLA. However, its sensitivity to water limits its use in polycondensation, where stannous chloride is commonly employed but is not capable of synthesizing high MW PLA. This study explores the use of stannous octoate for the synthesis of high MW PLA with higher yield.

Ultrasonic welding of Cork Wood/PLA composites: effect of welding factors on lap shear strength performance

Ultrasonic welding of Cork Wood/PLA composites: effect of welding factors on lap shear strength performance

Preparation of tomato peel pomace powder/polylactic acid foams under supercritical CO2 conditions: Improvements in cell structure and foaming behavior.

Polylactic acid (PLA) is an eco-friendly material that can help address the problems of petroleum depletion and pollution. Blending renewable biomass materials with PLA to create composite foams with a tunable pore structure, superior performance, and low cost is a green technique for improving the pore structure and mechanical characteristics of single PLA foams. PLA/TP composites were created using melted tomato peel pomace powder (TP), which has a lamellar structure, as a reinforcing agent. Then, the relationship between the vesicle structure, morphology, and properties of the PLA/TP composite foams produced through supercritical CO2 intermittent foaming were investigated. The findings revealed that TP considerably enhanced the rheological characteristics and crystalline behavior of PLA. The PLA/TP composite foam had a better cell structure, compression characteristics, and wettability than pure PLA. The expansion ratio of the PLA/TP composite could reach 18.8, and its thermal conductivity decreased from 174.2 mW/m·K at 100 °C to 57.8 mW/m·K at 120 °C. Furthermore, annealing before foaming decreased the average composite foam blister size from 110.09 to 66.53 μm, and the annealing process also improved compression performance. This study contributes to solving environmental difficulties and creating PLA foams with controlled bubble structures, uniform bubble sizes, and outstanding overall performance.

In Silico Evaluation of In Vivo Degradation Kinetics of Poly(Lactic Acid) Vascular Stent Devices.

Biodegradable vascular stents (BVS) are deemed as great potential alternatives for overcoming the inherent limitations of permanent metallic stents in the treatment of coronary artery diseases. The current study aimed to comprehensively compare the mechanical behaviors of four poly(lactic acid) (PLA) BVS designs with varying geometries via numerical methods and to clarify the optimal BVS selection. Four PLA BVS (i.e., Absorb, DESolve, Igaki-Tamai, and Fantom) were first constructed. A degradation model was refined by simply including the fatigue effect induced by pulsatile blood pressures, and an explicit solver was employed to simulate the crimping and degradation behaviors of the four PLA BVS. The degradation dynamics here were characterized by four indices. The results indicated that the stent designs affected crimping and degradation behaviors. Compared to the other three stents, the DESolve stent had the greatest radial stiffness in the crimping simulation and the best diameter maintenance ability despite its faster degradation; moreover, the stent was considered to perform better according to a pilot scoring system. The current work provides a theoretical method for studying and understanding the degradation dynamics of the PLA BVS, and it could be helpful for the design of next-generation BVS.