Mechanical Properties Of Polylactic Acid Research Articles

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.

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

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

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.

Synergistic effect of Co-MOF/epoxy modified tannic acid/ammonium polyphosphate on flame retardancy, anti-melt dripping and mechanical properties of polylactic acid

Achieving flame retardancy and anti-dripping properties in polylactic acid (PLA) while preserving its mechanical integrity remains a significant challenge. In this study, a novel organic ligand rich in phosphorus (P) and nitrogen (N) was synthesized and coordinated with Co2+ions to form a cobalt-based metal–organic framework (Co-MOF) with a multilayer mesoporous structure, acting as an effective carbonization agent. This Co-MOF was then compounded with epoxy-modified tannic acid (eTA) and ammonium polyphosphate (APP) to create a synergistic flame-retardant system for PLA (PLA/MAT). The Co-MOF provides numerous active sites for catalytic oxidation, promoting the formation of a uniform, hill-like expanded carbon layer. During pyrolysis, the Co-MOF and APP yield cobalt oxides and polyphosphates, which catalyze the dehydration of PLA and eTA, facilitating carbonization and forming a continuous, dense protective layer. Consequently, the PLA/MAT system exhibits both robust mechanical properties and excellent flame retardancy, as demonstrated by a limiting oxygen index (LOI) of 27.0 % and a UL-94 V-0 rating, with no melt dripping observed during combustion tests. This work offers a novel approach for enhancing the flame retardancy and anti-dripping performance of PLA, with potential applications in engineering, electronics, and the automotive industry.

Investigation on Tensile Properties of Polylactide-Nanoclay (PLA/ MMT) Surface Modification Nanocomposites

Polylactic acid (PLA) has gained significant attention as an environmentally friendly biopolymer, but its limited mechanical properties have hindered broader applications. Nanoparticles such as montmorillonite (MMT) offer a promising approach to address this limitation. The intercalation of MMT with polymer chains can significantly impact the mechanical properties of the nanocomposites. Hence, this paper investigated the effect of surface-modified montmorillonite (MMT) nanoparticles on the mechanical properties of polylactic acid (PLA) nanocomposites. The acetylation process of MMT was carried out followed by neutralisation process with NaOH. PLA granules and acetylated-modified MMT were mixed, crushed into granular form, and moulded. The effect of varying concentrations of modified MMTs on the tensile strength, elongation at break, and maximum force of PLA/MMT nanocomposites was evaluated using the ASTM D638 standard. FTIR results showed shifts in peak intensities in regions 2750 cm-1- 2810 cm-1 led to changes in the aliphatic and aromatic regions, which confirmed the presence of acetylation. Controlled surface modification improved interfacial interactions and load distribution, enhancing overall mechanical performance. The incorporation of surface-modified MMT in PLA/MMT nanocomposite increased the maximum force, Young's modulus, elongation at breaks and tensile strength. PLA/1wt% MMT and the PLA/7wt% MMT compositions exhibited good mechanical properties. However, the PLA/5 wt% MMT blendis deemed more suitable for food applications, such as disposable cups, plates, and cutleries, due to its lower elongation point. In conclusion, the hydrophilic properties of MMT and the hydrophobic properties of PLA are compatible due to the synergistic effects during surface modification which enhance the overall performance of the nanocomposites.

Enhancing the mechanical properties of polylactic acid (PLA) composite films using Pueraria lobata root microcrystalline cellulose

To enhance the mechanical properties of polylactic acid (PLA) material, the PLA-based composite films are prepared by using Pueraria lobata (Willd.) Ohwi root microcrystalline cellulose (PRMCC) treated with 3-aminopropyl triethoxysilane (KH550) silane coupling agent as the dispersed phase through solvent casting method. The effects of the concentrations of PRMCC and KH550 as well as the KH550 pretreating condition (ethanol concentration) on the tensile properties of PLA-based composite films are investigated. The PLA-based composite film treated with 5 wt% PRMCC and 18 wt% KH550 (pretreated by 90 % EtOH) exhibits the greatest performance. Its elongation at break value is detected to be 4.0 %, 1.6 times as large as that of pure PLA film. The water absorption of the as-prepared PLA-based composite film is reduced from 0.49 % of the unmodified PLA/PRMCC film to 0.12 %. Moreover, the modified PLA-based composite film has a hydrophobic surface and exhibits good thermal stability. Compared with pure PLA film, the modified PLA-based composite film exhibits improved UV shielding performance with acceptable transparency. Furthermore, after adding poly(butylene adipate-co-terephthalate) (PBAT) to the composite system, the elongation at break of the PLA-based composite film is up to 7.2 %. This research can provide theoretical guidance for enhancing the performance of PLA products.

Enhancing Mechanical Properties of PLA Filaments through Orange Peel Powder Reinforcement: Optimization of 3D Printing Parameters

This study investigates the augmentation of the mechanical properties of Polylactic Acid (PLA) filaments by incorporating Orange Peel Powder (OPP) as an eco-friendly filler for 3D printing applications. The study delves into optimizing the printing parameters to achieve enhanced mechanical characteristics while maintaining printability. Various 3D printing process parameters were analyzed systematically to assess their impact on tensile strength, flexural strength, and impact resistance. A thorough investigation was conducted to determine the impact of layer height, infill density, and printing speed on the overall mechanical properties of the printed specimens. The findings demonstrate that adding 25% OPP significantly enhances the mechanical strength of the PLA composite without compromising printability, with optimal concentration and printing parameters identified. Thermo gravimetric study reveals that the PLA/OPP composite filament has a higher maximum thermal degradation temperature of 329 °C, compared to the PLA’s temperature of 316 °C. This research contributes to advancing the development of sustainable and mechanically robust materials for additive manufacturing, offering insights into the fabrication of PLA-based biodegradable composites tailored for specific applications in various industries.

Nanoconfinement-Enhanced Fire Safety and Mechanical Properties of Polylactic Acid with Nanocerium Metal-Organic Frameworks.

Ce-based metal-organic frameworks (Ce-MOFs) were successfully synthesized by coordinating binary acid and amino structures with cerium oxides. The quantum dot scale endows Ce-MOFs with enhanced modifiability. Additionally, the phosphorus-rich biomass phytic acid, with its numerous hydroxyl groups, strengthens the H-bond network within the system. Ce-MOFs-centered nanoconfinement can form through the multiple H-bond interactions between Ce-MOFs and polylactic acid (PLA) molecules, thereby improving the mechanical and flame-retardant properties of PLA. The PLA/CeCxOy-P-3 composite exhibited excellent fire retardancy and toxic gas suppression, with a 27.8% decrease in the peak heat release rate and a 50% reduction in the peak smoke production rate. Notably, PLA/CeCxOy-P-3 showed an 80% lower peak CO release compared with the pure PLA sample. Moreover, the incorporation of Ce-MOFs positively influenced the tensile properties of PLA, transforming it from brittle to tough. This work designed and synthesized Ce-MOFs on the quantum scale. The resulting Ce-MOFs with the anticipated structure offer a novel direction for preparing MOFs for flame retardant applications.

The Effects of Nucleating Agents and Processing on the Crystallization and Mechanical Properties of Polylactic Acid: A Review.

Polylactic acid (PLA) is a biobased, biodegradable, non-toxic polymer widely considered for replacing traditional petroleum-based polymer materials. Being a semi-crystalline material, PLA has great potential in many fields, such as medical implants, drug delivery systems, etc. However, the slow crystallization rate of PLA limited the application and efficient fabrication of highly crystallized PLA products. This review paper investigated and summarized the influence of formulation, compounding, and processing on PLA's crystallization behaviors and mechanical performances. The paper reviewed the literature from different studies regarding the impact of these factors on critical crystallization parameters, such as the degree of crystallinity, crystallization rate, crystalline morphology, and mechanical properties, such as tensile strength, modulus, elongation, and impact resistance. Understanding the impact of the factors on crystallization and mechanical properties is critical for PLA processing technology innovations to meet the requirements of various applications of PLA.

Enhanced Crystallization of Sustainable Polylactic Acid Composites Incorporating Recycled Industrial Cement.

Globally, the demand for single-use plastics has increased due to the rising demand for food delivery and household goods. This has led to environmental challenges caused by indiscriminate dumping and disposal. To address this issue, non-degradable plastics are being replaced with biodegradable alternatives. Polylactic acid (PLA) is a type of biodegradable plastic that has excellent mechanical properties. However, its applications are limited due to its low crystallinity and brittleness. Studies have been conducted to combat these limitations using carbon or inorganic nucleating agents. In this study, waste cement and PLA were mixed to investigate the effect of the hybrid inorganic nucleating agent on the crystallinity and mechanical properties of PLA. Waste cement accelerated the lamellar growth of PLA and improved its crystallinity. The results indicate that the flexural and impact strengths increased by approximately 3.63% and 76.18%, respectively.

Effect of infill pattern on the mechanical properties of PLA and ABS specimens prepared by FDM 3D printing

Fused deposition modelling (FDM) is a three-dimensional printing technique which has become more popular and spreading in many fields. In this process, the molten thermoplastic is deposited layer by layer using a heated nozzle. Users can set the infill pattern to save the material and printing time. The main objective of this study is to investigate the tensile properties of polylactic acid (PLA) and Acrylonitrile butadiene styrene (ABS) tensile specimens with different infill patterns such as lines, tri-hexagonal and lightning. Further, the test specimens were prepared as per ASTM D638 using Ender 3D printer with varying infill patterns. The specimens were subjected to tensile tests in a mechanical tensile testing machine. It was observed that the specimens with linear infill patterns obtained higher tensile strength than the tri-hexagonal and lightning pattern infilled specimens. Later on, a microstructural study was examined on the fractured surface using scanning-electron-microscopy (SEM). It shows that the line pattern specimens have more uniform structure when compared to hexagonal and lightning pattern specimens.

Enhancing mechanical properties of polylactic acid through the incorporation of cellulose nanocrystals for engineering plastic applications

This study investigates the potential of enhancing the mechanical properties of polylactic acid (PLA) using cellulose nanocrystals (CNC). Recognized for their high specific strength and stiffness, CNCs are considered to improve the performance of PLA in engineering plastic applications. The synthesis involves a twin-screw extrusion process, which facilitates the uniform dispersion of CNC within the PLA matrix. The mechanical properties, including tensile strength and elongation at break, are comprehensively analyzed, highlighting the effects of CNC concentrations on the performance of PLA composites. Notably, the addition of 1 wt% CNC resulted in a 20% increase in strain at break compared to pure PLA, demonstrating enhanced ductility. Additionally, the thermal resistance of the composite increased by 0.3% with the inclusion of 5 wt% CNC. This study highlights the positive effect of CNC addition on the mechanical properties of PLA composites, making them more suitable for specialized engineering uses.

Optimizing FDM process parameters: predictive insights through taguchi, regression, and neural networks

Fused deposition modelling (FDM) is a popular additive manufacturing process used for rapid prototyping and the production of complex geometries. Despite its popularity, FDM’s susceptibility to variations in numerous process parameters can significantly impact the quality, design, functionality, and mechanical properties of 3D printed parts. This study explores thirteen FDM process parameters and their influence on the mechanical properties of polylactic acid (PLA) polymer, encompassing surface roughness, warpage, tensile and bending strength, elongation at break, deformation, and microhardness. The optimum parameters were identified alongside key contributors by applying the Taguchi method, signal-to-noise ratios, and analysis of variances (ANOVA). Notably, specific FDM parameters significantly affect the surface profile, with layer thickness contributing 32.65% and fan speed contributing 8.59% to the observed variations. Similarly, warping values show notable influence from nozzle temperature (29.53%), wall thickness (16.74%), layer thickness (16.56%), and retraction distance (12.80%). Tensile strength is primarily determined by wall thickness (31.83%), followed by infill percentage (26.73%) and infill pattern (16.18%). Elongation at break predominantly correlates with wall thickness (44.82%), with a supplementary contribution from nozzle temperature (10.90%). Microhardness lacks a dominant parameter. Bending strength variations primarily arise from layer thickness (38%), wall thickness (37.6%), and infill percentage (9.17%). Deformation tendencies are influenced by layer thickness (19.20%), print speed (11.37%), wall thickness, and fan speed (10.9% each). The optimized dataset of FDM process parameters was then employed in two prediction models: multiple-regression and artificial neural network (ANN). Evaluation based on the correlation coefficient (R2) and root mean squared error (RMSE) indicates that the ANN model outperforms the multiple-regression approach. The results indicate that precise control of FDM parameters, coupled with ANN predictions, facilitates the fabrication of 3D printed parts with the desired mechanical characteristics.

Effects of a phosphorus-nitrogen containing DOPO derivative on the flame retardancy and mechanical properties of polylactic acid foamed materials

In this study, a phosphorus-nitrogen flame retardant (DOPO-DABP) was synthesized by 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 4,4′-diaminobenzophenone (DABP). Then, polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), ammonium polyphosphate (APP), DOPO-DABP, Joncryl ADR-4370F(ADR), azodicarbonamide (ADC) and nano-SiO2 were used as raw materials to prepare flame-retardant modified PLA foamed materials by hot pressing. The synergistic effect of APP and DOPO-DABP not only effectively improves the flame retardancy of PLA foamed material, but also promotes their mechanical properties. The experimental results showed that when APP/DOPO-DABP=10/10, the vertical combustion grade (UL-94) of the material reached the V-0 level, the limiting oxygen index (LOI) was 34.4 %. The tensile strength of the material was 25.35 MPa, bending strength was 32.14 MPa. The cell diameter of the material was reduced to 46.72 μm, and the cell density of the material was 2.25×106/cm3.

Micromechanical Dilution of PLA/PETG-Glass/Iron Nanocomposites: A More Efficient Molecular Dynamics Approach.

Polylactic acid (PLA) and poly(ethylene terephthalate glycol) (PETG) are popular thermoplastics used in additive manufacturing applications. The mechanical properties of PLA and PETG can be significantly improved by introducing fillers, such as glass and iron nanoparticles (NPs), into the polymer matrix. Molecular dynamics (MD) simulations with the reactive INTERFACE force field were used to predict the mechanical responses of neat PLA/PETG and PLA-glass/iron and PETG-glass/iron nanocomposites with relatively high loadings of glass/iron NPs. We found that the iron and glass NPs significantly increased the elastic moduli of the PLA matrix, while the PETG matrix exhibited modest increases in elastic moduli. This difference in reinforcement ability may be due to the slightly greater attraction between the glass/iron NP and PLA matrix. The NASA Multiscale Analysis Tool was used to predict the mechanical response across a range of volume percent glass/iron filler by using only the neat and highly loaded MD predictions as input. This provides a faster and more efficient approach than creating multiple MD models per volume percent per polymer/filler combination. To validate the micromechanics predictions, experimental samples incorporating hollow glass microspheres (MS) and carbonyl iron particles (CIP) into PLA/PETG were developed and tested for elastic modulus. The CIP produced a larger reinforcement in elastic modulus than the MS, with similar increases in elastic modulus between PLA/CIP and PETG/CIP at 7.77 vol % CIP. The micromechanics-based mechanical predictions compare excellently with the experimental values, validating the integrated micromechanical/MD simulation-based approach.

Impact of strain rate on mechanical properties of polylatic acid fabricated by fusion deposition modeling

AbstractThe primary objective of this research is to investigate the impact of strain rate on the mechanical properties of polylactic acid (PLA) fabricated through fused deposition modeling. PLA material was fabricated in a grid pattern with 75% infill density, a 0.16 mm layer height, and a ± 45° printing direction. This study specifically investigated tensile strength, flexural strength, and interlaminar strength with respect to varying crosshead speeds (1, 2, 3, 4, and 5 mm/min). The highest tensile strength noted was 40.13 MPa at a cross—head speed of 5 mm/min. Maximum elongation of 7.1% was noted on cross head velocity of 1 mm/min, and the maximum interlaminar strength reached 76.04 MPa at 4 mm/min. At a crosshead speed of 4 mm/min, the tensile strength measured was 38.36 MPa, which is a value close to the maximum result achieved in the tensile test. Interlaminar strength was notably higher at a crosshead speed of 4 mm/min, indicating a strong integrity of the printed layers. The values for elongation percentage and flexural strength were also moderate at a crosshead speed of 4 mm/min, which was 4.9% and 55 MPa, respectively. Therefore, crosshead speed of 4 mm/min appears to be an optimum factor for testing 3D printed PLA parts. This research sheds light on understanding the critical influence of strain rate in the mechanical performance of 3D printed PLA.

Enhanced Flame Retardancy, Ultraviolet Shielding, and Preserved Mechanical Properties of Polylactic Acid with Fully Biobased Multifunctional Additives by a Green Method

Enhanced Flame Retardancy, Ultraviolet Shielding, and Preserved Mechanical Properties of Polylactic Acid with Fully Biobased Multifunctional Additives by a Green Method

Influence of SiC Doping on the Mechanical, Electrical, and Optical Properties of 3D-Printed PLA

Additive manufacturing, also known as 3D printing or digital fabrication technology, is emerging as a fast-expanding technology for the fabrication of prototypes and products in a variety of applications. This is mainly due to the advantages of 3D printing including the ease of manufacturing, the use of reduced material quantities minimizing material waste, low-cost mass production as well as energy efficiency. Polylactic acid (PLA) is a natural thermoplastic polyester that is produced from renewable resources and is routinely used to produce 3D-printed structures. One important feature that makes PLA appealing is that its properties can be modulated by the inclusion of nano or microfillers. This is of special importance for 3D-printed triboelectric nanogenerators since it can enhance the performance of the devices. In this work we investigate the influence of SiC micron-sized particles on the mechanical, electrical, and optical properties of a PLA-SiC composite for potential application in triboelectric energy harvesting. Our result show that the ultimate tensile strength of the pure PLA and 1%-doped PLA decreases with the number of fatigue cycles but increases by about 10% when SiC doping increases to 2% and 3%, while the strain at max load was about 3% independent of doping and the effective hardness was increased reaching a plateau at about 2 wt% SiC, about 40% above the value for pure PLA. Our results show that the mechanical properties of PLA can be enhanced by the inclusion of SiC, depending on the concentration of SiC. In addition, the same behavior is observed for the dielectric constant of the composite material increases as the SiC concentration increases, while the optical properties of the resulting composite are strongly dependent on the concentration of SiC.

An Optimized 3D Printer by Enhancing Material Properties and Surface Finish of PLA Through Modifications

This research investigates the optimization of 3D printer settings to enhance the mechanical properties of polylactic acid (PLA) printed parts. A fundamental aspect of this study involves the design and development of a 3D printer capable of accommodating varied printing parameters. The parameters under consideration include extruder temperature, layer height, print speed, and infill density. Through experimentation, the tensile strength and the bending strength of PLA material are systematically evaluated against these printing parameters. The results unveil significant correlations between printing parameters and mechanical properties. It is observed that increasing the extruder temperature up to 220°C increases the material strength, beyond which a decline is evident due to overextrusion and material degradation. Conversely, increasing the layer height leads to a reduction in strength, attributed to diminished layer adhesion and structural integrity. Moreover, decreasing print speed is found to enhance strength at the expense of increased print time, suggesting a trade‐off between efficiency and mechanical performance. Furthermore, the study demonstrates that augmenting infill density contributes to a notable increase in material strength, underscoring the importance of internal reinforcement in enhancing structural integrity. These findings provide valuable insights into the optimization of 3D printing processes for PLA materials, offering guidelines for achieving superior mechanical properties through precise calibration of printing parameters.

Characterizing polylactic acid/basalt fiber composite: Synthesis, characterization, and mechanical property evaluation

This investigation focused on enhancing the mechanical properties of polylactic acid (PLA) through the incorporation of basalt fibers and a maleic anhydride coupling agent. Basalt fibers, renowned for their high tensile strength and modulus, were selected as a potential reinforcement to augment PLA's mechanical performance. To optimize interfacial bonding between the hydrophilic PLA matrix and hydrophobic basalt fibers, maleic anhydride was employed as a coupling agent. The results indicate that the inclusion of 3 wt.% maleic anhydride and 10-20 wt.% basalt fibers significantly improved the composite's tensile strength by 40% and flexural strength by 51%. These findings underscore the potential of basalt fiber-reinforced PLA as a high-performance, sustainable material for diverse applications.