Papers by Keyword: PLA

Abstract: This scientific paper presents a comparative analysis of the mechanical characteristics of PLA samples fabricated through conventional AM methods and AM then ultrasonically compacted. The study aims to assess the potential advantages and limitations of ultrasonic compaction of PLA AM samples, as a reinforcing manufacturing technique. The methodology involves the fabrication of PLA samples using AM processes, then ultrasonically compact part of them to make a comparative study on their mechanical characteristics, including tensile strength. Additionally, the surface morphology and internal microstructure of the samples are analysed using microscopy techniques. The results of the study provide insights into the mechanical performance and structural integrity of the ultrasonically compacted samples compared to the conventionally PLA AM samples. The findings highlight any potential improvements or limitations in terms of mechanical properties, such as strength, durability, and overall performance.

Abstract: A pressure-induced autoclave foaming assisted by supercritical CO₂ of degradable polylactide (PLA) has been developed. A central composite design (CCD) of response surface methodology (RSM) is used to optimize three distinct process conditions: foaming temperature, pressure, and time. The mathematical model built for examining the effect of process conditions on the foam density and volume expansion ratio was verified and determined to be acceptable with an R-square value derived from the regression model of 0.930 and 0.934, respectively. The experimental and statistical results showed that of the three factors examined, the foaming pressure had the greatest impact on the density and volume expansion ratio of the PLA foams. The foaming temperature and time also had significant interaction impacts on both responses. It was observed that the following conditions are optimal for foaming of PLA, with a maximum VER of 10.107 and a minimum foam density of 0.123 g/cc: foaming temperature of 165.86 °C and foaming pressure of 152.4 bar for 2.38 h of foaming time.

Abstract: Growing interest in utilizing and processing natural fibres (NF) to create biodegradable and sustainable composites as environmental concerns upsurge globally. Date palm trees (DPT) account for more than 4.5 million tons of waste annually worldwide, making it one of the most abundant agricultural biomass waste in the MENA region. This study evaluated the biological resistance of thermoplastic composites developed from polylactic acid (PLA) and recycled polyvinyl chloride (RPVC) reinforced with date palm fibre (DPF) at different contents (10, 20, 30, 40 wt.%) and fibre size (250 – 500 µm and ≥1,000 µm). Composites where exposed to the brown-rot fungus; Irpex lacteus, and white-rot fungus; Tyromyces palustris, to evaluate its resistance to biodegradation. Results showed that composites developed using PLA had higher weight loss (%) when compared to the same samples but reinforced with RPVC. Composites with higher DPF content showed high rates of decay when used with different polymer matrix. Also, DPF length had a significant effect on the disintegration of the composites. DPF/PLA reinforced with 40 wt.% DPF showed the highest weight loss (WL%) reaching 5.61% and 5.46% when exposed to Tyromyces palustris and Irpex lacteus respectively. On the other hand, the biodegradation had a direct impact on the disintegration of the composites developed where the WL%, of PLA composites developed with 40 wt.% DPF showed 61.40%.

Abstract: 3D-printing technology is being used as a regular approach in prototyping and the production of machine components. However, despite their metallic counterparts, there are many issues including infill pattern, density, and stress concentration coefficient in 3D printing that are not well-defined. The infill density plays a significant role in the printing time and mechanical properties of the printed objects. On the other hand, like metallic materials, changing geometry, such as fillet radius and hole alters the strength of the printed elements. In this work, experimental works have been conducted to determine the effect of infill density on the tensile strength of 3D printed elements. Furthermore, various standard specimens for tensile testing have been prepared to investigate the effects of fillet radius and in-plane hole diameters on the tensile strength of PLA 3D-printed elements with different infill density. Using the experimental results, the tensile stress concentration coefficients as a function of fillet radius, hole diameters, and infill density have been determined. The results of the present work can be used as a guideline for analytical design and manufacturing 3D printing objects.

Abstract: Emerging trends in extrusion-based additive manufacturing (AM) focus on improving the mechanical performance of pristine polymers with high strength reinforcing materials. Prominent reviews have indicated a heavy dependence on PLA polymer for fused deposition Modeling (FDM) based studies. To promote biodegradability, the effect of natural fibres as reinforcement has been widely researched in the literature. However, it is noted that discontinuous natural fibre reinforcement yields negative or negligible improvement in the strength and modulus of FDM-based biocomposites. Hence, an attempt to hybridise FDM with a conventional composite manufacturing method was made in this study by cladding natural fibre reinforcement over FDM-based polymer. Tensile and flexural test coupons were additively manufactured by FDM and reinforced with a skin of bi-directional woven basalt fibre through compression moulding. A 90% improvement in tensile strength and a similar significant increase in flexural strength was observed. Further, an average increment of 46.38% and 237.24% in tensile and flexural modulus, respectively, was achieved through this manufacturing technique. In conclusion, a drastic improvement in mechanical performance can be obtained through the hybridisation of manufacturing methods and needs further investigation towards the compatibility of adhesive materials with FDM polymers.

Abstract: Metal particle reinforcement plays an important role in the mechanical properties and printability of composite materials for FDM 3D-printing technology. PLA/Iron composite filament is widely used in many applications, such as magnetic and biomedical devices. This research aims to study the effect of iron particles on the printability and mechanical properties of PLA/Iron composite and compare it with another PLA composite of PLA/Stainless steel composite. The PLA/Iron (Fe) and PLA/Stainless steel (SS) composites were printed at different printing temperatures between 260-290 °C, printing speeds between 30-90 mm/s, and infill density of 100%. The max stress and elongation of printed PLA/Fe composite were higher than that of printed PLA/SS composite about 1.5 and 1.2 times. Moreover, the highest max stress of printed PLA/Fe composite specimens was 40.20 MPa at a printing temperature of 280 °C and printing speed of 60 mm/s. The optical microscope observed the homogeneous iron and stainless-steel particle distribution in PLA composite matrix and revealed the printed structure.

Abstract: Fused deposition modelling (FDM) is a spectrum of techniques that enables the fabrication of objects from diverse materials, layer-by-layer, and directly from a CAD file. With the advancement of technology, the procedure has grown more adaptable and swifter. In this study, the mechanical performance and topology optimization of the polylactic acid (PLA) 3D printed hollow and thin-walled structures produced by FDM was investigated via integration of Taguchi method and Principal Component Analysis (PCA). Eleven factors namely topology design (square), wall thickness (1 mm), layer height (0.3 mm), infill density (20%), infill layer thickness (0.6 mm), infill flow (80%), infill pattern (Octet), print speed (80 mm/s), printing temperature (210°C), bed temperature (65°C), and orientation direction (flat along the y-axis) were identified as the optimal factors for the 3D printed part. The integration approach concurrently solves the problem in particular for numerous quality criteria, especially in 3D printing. Integrating the Taguchi method with PCA can help to improve the quality of the final product or process, and enhance the understanding of the underlying relationships between variables.

Abstract: Natural fibers possess the advantage of low cost, abundant in quantity and biodegradability. Rising awareness about green products and supportive government regulations are likely to propel the growth in the field of green composite. In this current research, a comparative study of mechanical characteristics and water absorption behaviour of green composites incorporating Aloe Vera and pineapple leaf fibers in biodegradable matrix (polylactic acid) has been experimentally examined. Composite has been developed using compression molding technique. The effect of surface modification of fibers on mechanical properties and water absorption behaviour of developed composite was investigated. Surface treatment was done using alkaline solution of sodium hydroxide having concentration of 5%. Treatment of fiber enhanced tensile, flexural, microhardness and impact properties of developed green composite and reduces water absorption capacity. Moreover, experimental results show that Aloe Vera reinforced composites have better mechanical properties in comparison to Pineapple leaf fiber reinforced composites. Thereby having potential to be used in various engineering applications

Abstract: Additive Manufacturing (AM) has been one of the technologies that has been booming in recent years. Its main advantages are the versatility in the manufacture of parts, the ability to print limited series and its low acquisition cost, among others. Among these technologies, one of the most widely used by engineering and product design teams is Fused Filament Fabrication (FFF). PLA being one of the materials most employed for FFF. Likewise, for a proper shaping of this material and process, it is necessary to establish several parameters to define the quality and properties of the designed part. In this context, a comparison of two groups of pieces has been carried out. Whereas the first group exhibits a correct process parameters and an adequate calibration of the printing bed; the second, has not any bonding between layers or bonding of beads of the same layer, due to an incorrect establishment of the initial parameters. In order to compare these groups, a study of the internal structure was carried out by X-Ray CT along with a characterization of their tensile mechanical properties. Results show a similar maximum stress for both groups, but a drastic reduction of the plastic area in the parts with defects. The quantification and comparison of the mechanical properties of both tests might provide a rejection criterion for parts that work in tension and present defects similar to those studied for engineering teams in product design.

Abstract: Nowadays, tools such as Additive Manufacturing (AM) contribute directly to an increase in the value of Industrial Design through the development of new products focused on customization. Specifically, the acoustic guitar is a good example of this, because it is a complex product to study due to the great variety of possible designs depending on the materials and the way they are obtained, which has repercussions on the final sound of the instrument. Due to the above, this paper develops a methodology for the study of the acoustic response depending on the design of an acoustic guitar using AM with Polylactic Acid (PLA) material. The methodology is divided into two types of tests: an acoustic test to capture the frequencies emitted by transmitting a sweep of frequencies across the audible spectrum to the soundboard, and another to visualize the vibrational patterns at five specific harmonic frequencies of the guitar by analyzing the movement of the soundboard and the influence of the bracing. This second test includes the PLA designed top with a reinforcement structure in its soundboard and a case in order to compare this design with a wooden guitar of the same size whose top has no reinforcement at all. From the tests carried out, it can be seen that the acoustics recorded by a top made of PLA can provide a good acoustic response compared to a wooden guitar, giving the possibility to create customized guitars according to the musician's tastes.