Papers by Author: Ahmad Haji Sahrim

Abstract: The current research was conducted to study the incorporation of phosphorus-based flame retardant (exolit OP 1230) and phosphonium salt treated montmorillonite (P-MMT) into polyol resin of polyurethane foam, with the purpose of imparting its compression properties and flammability resistance. To prepare the hybrid composite with a 2.5 wt% based on weight percentage of the overall weight of the system, fractions of exolit OP 1230 are mixed with P-MMT following a percentage ratio of 25/75, 50/50 and 75/25. The result of the mechanical property testing showed that the compression strength of composite was decreased with the presence of exolit OP 1230. However, the result obtained also demonstrated that the fire behaviour of the foam was improved. The study indicated that a combination of exolite OP 1230 and P-MMT generates a synergistic mechanism effect which could be used as an effective fire retardant as compared to sample with a 2.5% P-MMT alone. On the other hand, horizontal burning test following an ASTM D635 test procedure was conducted to determine the burning rate and bomb calorimeter model Ika C5003 was employed to detect the combustion enthalpy in this study. Finally, the findings of the analysis of the mechanical properties were further supported by the SEM micrographs.

Abstract: Pre-mixed NiZn ferrite/MWNT, according to the weight ratio 1:1, were incorporated into the thermoplastic natural rubber nanocomposite by melt blending process. The effect of different filler loadings (2-10 wt%) on reflection loss and shielding effectiveness of the obtained composites were studied. It was found that both reflection loss (RL) and shielding effectiveness (SE) depend on the filler content. The effect of fillers mixing ratio were investigated too. Results showed samples with higher MWNT content exhibits better shielding effectiveness, while samples with higher NiZn ferrite achieved better reflection loss. The microwave absorbing properties of these samples can be adjusted according to desired application.

Abstract: Thermoplastic natural rubbers (TPNR) blends consist of thermoplastics, such as low density polyethylene (LDPE), alloyed with natural rubber (NR) with different thermoplastic to NR ratios. The soft grade TPNR is produced by blends with compositions richer in rubber while the harder grades can contain up to about 30% NR. This study investigate the influence of new binder system containning of TPNR on injection parameter, density of injected molded specimen and changes during solvent extraction. Results shows that TPNR plays an important role as a good binder system and shortens the solvent extraction process.

Abstract: In this study, nanoclay and multi-wall carbon nanotubes have been used as a dual filler in an epoxy matrix. In the design of the experiment (DOE) the Taguchi Method was selected to study the effect of the factors involved in this study. The effect of the clay/MWNT ratio, types of solvent, clay cation, composition of LENR, cure time and cure temperature on tensile properties of the epoxy nanocomposites were investigated. The confirmation experiment obtained from Taguchi analysis, achieved 57% improvement in tensile strength. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the presence of intercalated and aggregated structures. Due to the lower crosslink density of the system, a decrease in decomposition temperature and glass transition temperature was observed in the optimum sample.

Abstract: Recently, research on natural fiber reinforced polymer composites has gained importance due to the abundant sources of fibers that can be obtained at very low cost. In this study, wood plastic composite (WPC) materials is made by mixing (compounding) high density polyethylene (HDPE) and (ligno) cellulose fiber, i.e. rice husk reinforced with sawdust have been manufactured using a high volume process using counter rotating twin screw extruder. Different fire retardant agents have been employed in order to improve fire behavior in this study. The flammability and thermal stability of WPC-HDPE based in different compositions have been carried out by fire test method according to ASTM D635-06 and evaluated by thermo gravimetric analysis respectively. The properties of flexural strength and impact strength were also included.

Abstract: We investigated the effects of amount of antioxidants variability on selected mechanical and physical properties of wood plastic composites. Recycled high density polyethylene (rHDPE) and natural fibers were compounded into pellets by compounder, then the pellets were extruded using co-rotating twin-screw extruder and test specimens were prepared by hot and cold press process. From the study, samples with 0.5 wt% of antioxidants produce the highest strength and elasticity of composites. The effect of antioxidants presence on water uptake is minimal.

Abstract: Nanocomposites prepared from blend of high density polyethylene (HDPE), natural rubber (NR) and organoclay were melt compounded using an internal mixer. The phase morphology and mechanical properties of this thermoplastic natural rubber nanocomposites samples were examined. The transmission electron microscope (TEM) and wide angle X-ray scattering (WAXS) was used to determine the exfoliation of organoclay in this blend. The tensile and Izod impact test were used to evaluate the mechanical properties of HDPE/organoclay nanocomposites with and without the presence of NR. The Izod impact results shows an improvement more than 300% with addition of 10% NR content in the matrix. The X-ray diffraction results indicated intercalation of blend into the silicate interlayer of nano-filler I.44P and partially exfoliation of silicate layer into the blend. The SEM morphology revealed that there was some part of uneven dispersion of organoclay in the blend.