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Sol-gel method is the simplest method and has the ability to control the particle size and morphology through systematic monitoring of reaction parameters. The objective of this research is to synthesize silica nanostructures by sol-gel method and to characterize the synthesized silica nanostructures. Silica nanoparticles were synthesized via the sol-gel method using Tetraethyl orthosilicate as a precursor. The acetic acid and distilled water were used as the catalyst and the hydrolyzing agent. Varied parameters of the study were the aging time in the range of 2 to 6 h and the calcination temperature in the range of 600-700• C. The obtained silica nanopowder was characterized using FESEM, and Nano-Particle Size Analyzer. The results show that the silica nanospheres were successfully synthesized by using sol-gel method with the optimum parameters of 700• C of calcination temperature and 2 h of aging time. The average size of silica nanoparticles was in the range of 79.68 nm to 87.35 nm.

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Kenaf fiber (KF) based thermoplastic natural rubber (TPNR) composite was produced by melt blending with polypropylene (PP). Kenaf fiber (15% by volume) and TPNR were mixed in as Haake 600p internal mixer. The fracture behavior of the TPNR matrix and of TPNR-kenaf (with and without maleic anhydride grafted polypropylene, MAPP) composites was evaluated using the essential work of fracture (EWF) method and double edge notched tensile (DENT) specimens. Various ligament lengths were employed ranging from 4 to 12 mm. The strain rate was fixed at 2 mm/min. The specific work of fracture (w e ) and plastic work (bw p ) showed the highest energy for TPNR that corresponds to its ductility and allows the application of the EWF approach. It was found that the presence of kenaf fibers and MAPP reduced the toughness of TPNR and changed the ductile fracture to brittle behavior. SEM observation revealed that energy absorption mechanisms include matrix deformation, fiber pullout, and fiber breakage. Acoustic emission (AE) was employed to analyze the failure processes further. The signals emitted by composites were substantially higher than that of the TPNR matrix, reflecting that also the failure mechanisms were affected by the fibers incorporated.KEY WORDS: thermoplastic natural rubber, kenaf fiber, essential work of fracture, acoustic emission.

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The effects of woven and non-woven kenaf fiber on mechanical properties of polyester composites were studied at different types of perform structures. Composite polyester reinforced kenaf fiber has been prepared via hand lay-up process by varying fiber forms into plain weave, twill and mats structure. The reinforcing efficiency of different fiber structure was compared with control of unreinforced polyester sample. It was found that the strength and stiffness of the composites are largely affected by fiber structure. A maximum value for tensile strength of composite was obtained for twill weave pattern of fiber structure while no significant different for plain weave and mat structure. The elastic modulus of composite has shown some improvement on plain and twill weave pattern. Meanwhile, lower value of modulus elasticity achieved by mats structure composite as well as control sample. The modulus of rupture and impact resistance were also analyzed. The improvement of modulus of rupture value can be seen on plain and twill weave pattern. However impact resistance doesn't show significant improvement in all types of structure except for mat fiber. The mechanical properties of kenaf fiber reinforced polyester composite found to be increased with woven and non-woven fiber structures in composite.

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Nanostructured coatings offer great potential for various applications due to their superior characteristics that are not typically found in conventional coatings. This research aimed at developing a new and improved coating that employs zinc oxide nanopowder as the agent to achieve corrosion resistant properties for a coating. The research project discusses on its corrosion behaviour of epoxy-zinc oxide in different media by measuring its corrosion rate. Mild carbon steel was used as the substrate for the epoxy-zinc oxide coating. The corrosion behavior mechanism of mild steel was investigated in different media, namely fresh water, NaCl solution, HCl solution and NaOH solution. Immersion test was conducted and studied for a period of 60 days, with daily and weekly weighing and immersing. The corrosion rate was calculated and mild steel corrodes in the different environment and degrades in the following trend; HCl → NaCl → NaOH → H2O.