Now showing 1 - 3 of 3
  • Publication
    The Effects of Self-Polymerized Polydopamine Coating on Mechanical Properties of Polylactic Acid (PLA)–Kenaf Fiber (KF) in Fused Deposition Modeling (FDM)
    This research examines the impact of self-polymerized polydopamine (PDA) coating on the mechanical properties and microstructural behavior of polylactic acid (PLA)/kenaf fiber (KF) composites in fused deposition modeling (FDM). A biodegradable FDM model of natural fiber-reinforced composite (NFRC) filaments, coated with dopamine and reinforced with 5 to 20 wt.% bast kenaf fibers, was developed for 3D printing applications. Tensile, compression, and flexural test specimens were 3D printed, and the influence of kenaf fiber content on their mechanical properties was assessed. A comprehensive characterization of the blended pellets and printed composite materials was performed, encompassing chemical, physical, and microscopic analyses. The results demonstrate that the self-polymerized polydopamine coating acted as a coupling agent, enhancing the interfacial adhesion between kenaf fibers and the PLA matrix and leading to improved mechanical properties. An increase in density and porosity was observed in the FDM specimens of the PLA–PDA–KF composites, proportional to their kenaf fiber content. The enhanced bonding between kenaf fiber particles and the PLA matrix contributed to an increase of up to 13.4% for tensile and 15.3% for flexural in the Young’s modulus of PLA–PDA–KF composites and an increase of up to 30% in compressive stress. The incorporation of polydopamine as a coupling agent in the FDM filament composite led to an improvement in tensile, compressive, and flexural stresses and strain at break, surpassing that of pure PLA, while the reinforcement provided by kenaf fibers was enhanced more by delayed crack growth, resulting in a higher strain at break. The self-polymerized polydopamine coatings exhibit remarkable mechanical properties, suggesting their potential as a sustainable material for diverse applications in FDM.
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  • Publication
    Effects on Ply Orientation of Kevlar/Epoxy for Ballistic Impact in Bulletproof Vest Using Non-linear Finite Element Analysis
    The bulletproof vest is vital equipment to stop bullets from penetrating the body. The vest comes with a ballistic panel that can absorb the energy from the ballistic impact. Due to excellent impact resistance and high strength-to-weight ratio, Kevlar fibers composites are widely used for designing a ballistic panel in bulletproof vest body armor to avoid penetration. In this study, the research aims to investigate the ballistic impact behavior on a ballistic panel of Kevlar/Epoxy by using different fibers ply orientation to increase the ballistic impact performance. A finite element analysis using non-linear dynamic simulation was developed in commercial software Abaqus/Explicit to analyze the performance of impact characteristics in penetration depth, damage criteria, and energy-absorbing capacity. The simulation results show that the fibers ply orientation sequence of [0/90/0/90]2sym with 4 mm panel thickness has produced the highest energy absorption of 1523.7 J with least depth penetration of 2.12 mm for the 9 mm bullet traveling at 358 m/s and produce a lowest Hashin’s damage criteria with the value of 0.40. The finding shows that the ply orientation of Kevlar/Epoxy composite ballistic panel has excellent potential in bulletproof body armor application for minimizing the effect of blunt force trauma with less expensive materials usage and light weight ballistic panel.
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  • Publication
    Tensile Properties of 3D Printed Recycled PLA Filament: A Detailed Study on Filament Fabrication Parameters
    Polylactic acid (PLA), a biodegradable and biocompatible thermoplastic commonly utilized in 3D Printing filaments, undergoes changes in properties upon recycling. The objective was to elucidate the role of extrusion temperature and screw speed in modulating the quality of recycled PLA filament, as well as in controlling its dimensional attributes. Recycled PLA pellets (3D850D) were extruded using a single filament extruder machine within an extrusion temperature range of 145°C to 165°C and a screw speed varying from 2 rpm to 6 rpm. The extruded filaments were subsequently 3D printed into specimens adopting a 0° raster angle, line infill pattern, and a 100 percent infill density, then tested as per ASTM D638 mechanical standards. The study revealed a profound influence of extrusion parameters on the filament's ultimate tensile strength, yield strength, and diameter. Optimal extrusion conditions-155°C and 5 rpm-resulted in maximum mechanical strengths, while the parameters yielding filament diameters closest to commercial standards were identified as 5 rpm and 155°C. These results under-score the possibility of optimizing the recycled PLA filament's properties through adept control of extrusion parameters. Consequently, this investigation supports the potential use of recycled PLA filament in the 3D printing industry as a sustainable and performance-efficient material, offering a tangible step towards environmentally friendly additive manufacturing practices.
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