Browsing by Author "Norhasnidawani binti Johari"

This study was undertaken to enhance the properties of kenaf core epoxy matrix in sandwich structure, in addition to improve on mechanical, thermal and morphological properties. Sandwich panel was prepared by hand lay-up method. Sandwich panel were prepared in the ratio of 30wt%:70wt% from kenaf fiber and epoxy. The kenaf fiber was treated with natrium hydroxide (NaOH) to improve the interaction between fiber-matrix. Liquid natural rubber (LNR) was used as impact modifier and toughened agent in order to modify the epoxy matrix within 0wt%-5wt% of LNR. Mechanical test such as flexural, drop impact and tensile test were performed to investigate the optimum system of kenaf-core sandwich panel. All tests have been carried out according to the ASTM 365, C297, C393, and D1736. Each final data point is an average value that has been obtained based on a statistical sampling of six specimens. The main element of core structure is kenaf and the skin used in this study is aluminium type 1100. According to compression, flatwise tensile, three point bending and drop impact tests, 3wt% of LNR content exhibit as an excellent impact modifier, in modifying the mechanical properties due to rubber toughening. The mechanical properties of sandwich panel showed an increasing trend up from 0 wt% to 3 wt% of LNR content with optimum tensile strength 37.62 MPa and 21.6% increase in Young's modulus. The addition of 5wt% was substantially interrupted the system. These findings were also supported by scanning electron micrograph (SEM). SEM micrograph further showed that LNR act as impact modifier and cushioning by absorbing the energy and transfer within the matrix, preventing the crack from continuing cracking on the sandwich panel. TGA results showed that with the presence of LNR could improve the thermal stability of sandwich panel with high degradation temperature. Thus, all sandwich panels contain LNR show higher thermal stability compared to the kenaf core with neat epoxy. Water absorption was inversely proportional with the increasing of LNR composition into kenaf core epoxy matrix which was two times lower than kenaf core epoxy composite without rubber. All the results showed that the sandwich structure in the presence of LNR greatly increased the performance of sandwich structure when rubbery particles dispersed throughout the thermoset matrix.

Numerous coating compositions were developed and yet most of them are incapable to overcome several limitations in adhesion and effectiveness as anti corrosion. This research aimed at developing a new and improved coating that employs of zinc oxide (ZnO) and silica (SiO2) nanoparticles as the agent for anticorrosion coating. This research was divided in two main phases; phase1, synthesis of ZnO-SiO2 nanoparticles by sol gel method and phase 2, preparation of coating sample. ZnO was selected due to its special characteristics such as anti-corrosion, anti-bacteria and excellent heat resistance, while SiO2 was used to increase the consistency of coatings, giving good adhesion and low-cost flatting agents. These coatings were formulated through copolymerization of epoxy resin with the incorporation of ZnO and SiO2 nanoparticles. ZnO and SiO2 were synthesized using sol-gel method. Epoxy acted as host while the nanoparticles incorporate as guest components. The coating was directly applied onto carbon steel type S50C as the substrate. The tests of adhesion, immersion, UV, humidity and salt spray were carried out in accordance to ASTM D3359, B895, D4587, D2247 and B117-94 respectively. The results of FESEM and nano-particle size analyzer showed that the SiO2 and ZnO nanoparticles were successfully synthesized with the range sizes of 79.68 nm to 87.35 nm and the 81.28nm to 84.98nm respectively. Based on thermal analysis, contribution of nanoparticles possessed better thermal stability. Nanoparticles improved the quality of the cured epoxy coating, reduced the porosity of the coating matrix and improved barrier performance of the epoxy coating. Nanocoatings having good adhesion with the substrate in NaOH, H2O and HCl medium, formed hydrophobic surface for deionized water dropping and can withstand long protection from corrosion process in salt spray testing. Nanocoating demonstrates good anticorrosion behavior and good adhesion properties with significant thickness. Incorporation of 3 wt% of ZnO and 2 wt% of SiO2 nanoparticles were the best composition for nanocoating and produce novelty in improving coating properties.