Papers by Author: Abu Bakar Sulong

Abstract: Nowadays, micro metal injection molding has become among the promising method in powder metallurgy research to produce small-scale intricate part at an effective process and competitive cost for mass production. This paper investigated the optimization of highest green strength which plays an important characteristic in determining the successful of micro MIM. In this paper, stainless steel SS 316L with D50 = 5.96µm was used with composite binder, which consists of PEG (Polyethelena Glycol), PMMA (Polymethyl Methacrilate) and SA (Stearic Acid). Feedstock with 61.5% with several injection parameters were optimized which highly significant through screening experiment such as injection pressure(A), injection temperature(B), mold temperature(C), injection time(D) and holding time(E). Besides that, interaction effects between injection pressure, injection temperature and mold temperature were also considered to optimize in the Taguchi’s orthogonal array. Analysis of variance (ANOVA) in terms of signal-to-noise ratio (S/N-larger is better) for green density was also presented in this paper. Result shows that interaction between injection temperature and mold temperature(BxC) give highest significant factor followed by interaction between injection pressure and mold temperature(AxC). Single factor that also contributes to significant optimization are mold temperature(C) and injection time(D). This study shows that Taguchi method would be among the best method to solve the problem with minimum number of trials.

Abstract: Optimization process for fabrication of Carbon nanotubes (CNTs) reinforced Polyethylene (PE) fibers by melt spinning has been studied. Three main melt spinning process parameters (spinning temperature, spinning distance, and spinning revolution) are evaluated by the Taguchi’s method to decrease the diameter of fibers. Decreasing diameter of fibers is greater influenced by spinning revolution and distance than spinning temperature. Moreover, fibers in diameter 22 μm (average) are successfully fabricated. Mechanical properties are measured by tensile test machine based on ASTM D3822 for single fibers which were fabricated at optimized melt spinning process parameters. Pure PE polymer fibers and chemically surface modified CNTs reinforced fibers also fabricated for comparison purpose. The interfacial bonding of CNTs with PE matrix is investigated through fracture surfaces image analysis by Scanning Electron Microscopy (SEM).

Abstract: The dynamic thermo-mechanical properties of two types of chemically surface modified (Carboxylated and Octadecylated) multi-walled carbon nanotubes (MWCNTs) and As produced MWCNTs reinforced epoxy matrix composites are investigated by Dynamic Mechanical Thermal Analyzer at 1.0 wt% concentration. Moreover, influence of MWCNTs concentration variations to the dynamic thermo-mechanical properties are evaluated at Carboxylated MWCNT reinforced polymeric composites (from 0.1 to 5.0 wt %). Higher interfacial bonding strength is achieved by introducing the chemical surface modification. Also MWCNTs reinforced polymer shows higher storage modulus (from 30°C to 70°C) than pure polymer. Moreover, the storage modulus of composites increases linearly by increasing MWCNTs concentration. However, glass transition temperature (Tg) of composites decreases linearly by increasing MWCNTs concentration.