Key Engineering Materials Vols. 594-595

Abstract: A review is given of polyolefins layered silicates nanocomposites. This group of commodity thermoplastic is widely used and gain a great attention among researcher now days for nanocomposite preparation with layered silicates as inorganic filler. Herein, the structure and properties of layered silicates, compatibilzations of polyolefins, the syhthesise preparative method are discussed in general.

Abstract: Warpage is a type mold defect due to non-uniform temperature variation which causes differential shrinkage rate on the moulded parts. An accurate warpage prediction is so important in helping mould designers to achieve successful mold design with minimum warpage defects. This work is performed with a purpose to determine and compare the best parameters can be selected in manufacturing of thin shallow shell using two different types of cooling channels which are straight cooling channels and conformal cooling channels. The results were obtained using Taguchi Method and Analysis of Variance (ANOVA) and run through simulation software. Both parameters are then compared with each other in recommending to the mold designers which is the best to be applied at mold design stage. It has been found from this work that two factors that significantly cause warpage on both cooling channels are packing pressure and filling time.

Abstract: The foam was prepared by mixing the polyols, isocyanate and carbonnanotubes (CNTs) at 1000 rpm speed. The different content of the CNTs are varies from 0 3 (0, 0.5, 1.5, 2.0, 2.5, 3.0) percent by weight. The foam sandwich was prepared by using hand lay-up method with epoxy and hardener as the adhesive to bind the surface between Polyurethane (PU) - CNTs and Aluminium (Al) sheet. The effect of different CNTs content was studied on the compression test and energy absorption. The compression test results show fluctuated values with increasing percentage of CNTs in PU foam. This trend may due to particles agglomeration as the nanosize of CNTs can make the particles to agglomerate easily due to the strong adhesive force between the nanoparticles. The size of the CNTs particles might not similar thus it is believed that the distribution of the particles were not well. Increasing in percentages of CNTs in PU foam found to improve the energy absorption from 0.115 J for control PU foam to 0.140 J for PU-CNTs foam with 3% CNTs.

Abstract: In this study, Pultruded Kenaf Reinforced Composites (PKRC) has been successfully produced using pultrusion technique. The chemical treatment using sodium hydroxide (NaOH) at different concentration (3%, 6% and 9% M) were carried out to modify the fibre properties. After successfully characterized, it was found that kenaf fibre treated with 6% NaOH recorded the best improvement in term of mechanical properties. In particular, treated pultruded kenaf reinforced composites (TPKRC) shows better tensile and flexural properties compared to those of untreated pultruded kenaf reinforced composites (UTPKRC). It was found that NaOH at 6% concentration give the best composite properties in term of mechanical properties over the range of NaOH concentration studied.

Abstract: The gel polymer electrolytes (GPEs) composed of polymethylmethacrylate (PMMA) with sodium trifluoromethanesulfonate (NaCF₃SO₃) salt dissolved in a binary mixture of ethylene carbonate (EC) and propylene carbonate (PC) organic solvents have been prepared by solution casting technique. The samples are prepared by varying the salt concentrations from 5 wt.% to 30 wt.%. Impedance spectroscopy measurement has been carried out to determine the ionic conductivity of the GPE samples. The sample containing 20 wt.% of NaCF₃SO₃ salt exhibits the highest room temperature ionic conductivity of 3.10 x 10^-3 S cm^-1. The conductivity of the GPEs has been found to depend on the salt concentration added to the sample though at higher salt concentration reveals decreasing in ionic conductivity due to ions association. The temperature dependence of conductivity from 303 K to 373 K is found to obey the Arrhenius rule. The ionic transference number, ti of GPEs has been estimated by DC polarization method and the value is found to be 0.95, 0.99, and 0.97 for the sample containing 5 wt.%, 20 wt.% and 30 wt.% respectively. This result is consistent with the conductivity studies.

Abstract: Miniaturisation of electronic chips which have increasing functionality within the same package size has induced significant increases in requirements for extraction of heat from the integrated circuit (IC). Packaging materials therefore have to be capable to conduct heat efficiently and at the same time have low coefficient of thermal expansion (CTE) to minimize the thermal stress and warping. In the present study, copper silicon carbide was selected with an aim to solve thermal management problem presented by current IC systems. Powder metallurgy routes were chosen to fabricate the MMC based on this materials system. Copper and silicon carbide powders were mixed together in a planetary ball mill, and the green articles were then compacted and sintered to produce the final product of CuSiC. The sintering parameters were investigated for their effects towards the thermal conductivity of the composite. Sintering parameters investigated included temperature, heating duration and the gaseous environment. Upon sintering, the CuSiC particle bond to one another giving a higher strength and a possibility in attaining desirable density. Thus to achieve good thermal conductivity, the recommended sintering parameter suggests that the CuSiC composite should be sintered at 950°C for 7 hours in nitrogen gas.

Abstract: In this paper presents the effect of energy absorption on thin-walled aluminum cross-section square tubes wrapped with woven E-glass fiber laminated composite subjected to quasi-static axial compression. The compression test was carried out experimentally to examine the amount of energy can be absorbed as well as to observe for failure behavior for each specimens. The wall-thicknesses aluminum square of 1.9 mm was investigated and woven E-glass fiber laminate reinforced polyester resin was examined. Two different numbers of layers woven E-glass were investigated and examined. Result obtained from experimental analysis such that initial peak load, mean load, quasi-static absorbed energy against displacement curves were recoded and plotted then compared for each specimen profile. Results indicated that the tubes crashworthy structure was affected significantly by different number of layers wrapped on wall aluminum square profile and also that the effect of crushing behaviors and failure modes was discussed.

Abstract: The present paper determines the effect of crush force efficiency on laminate glass wrapped on aluminum cross-section square tubes under quasi-static loading. The analysis was examined via experimentally. The wall-thicknesses aluminum square of 1.6 mm was investigated on wrapped woven composite type of E-glass fiber reinforced polyester resin. Two different numbers of layers woven E-glass were investigated and examined. Result obtained from experimental analysis such that initial peak load, mean load, versus displacement curves were compared for each specimen. Results showed that the tubes energy absorption was affected significantly by different number of layers wrapped on wall aluminum square profile and also that the effect of crushing behaviors and failure modes was discussed.

Abstract: The spear grass content on the tensile properties, morphology of low-density polyethylene (LDPE)/spear grass was investigated. The compatibilising effect of epoxidised natural rubber (ENR 50) LDPE and spear grass was mixed by using twin screw extruder with various spear grass contents. The tensile properties were tested by using an Universal Testing Machine (UTM). The tensile strength and elongation at the break point were significantly improved by the addition of ENR 50, as evidenced by morphological analysis using scanning electron microscopy (SEM). On the other hand, the tensile modulus increased with spear grass content up to 10% and decreased thereafter.Keywords: Epoxidised Natural rubber (ENR), Low Density Polyethylene (LDPE), Spear Grass, Tensile Properties

Abstract: The research aim is to investigate the effect of alkali treatment on the crystalline structure of Mendong fiber. The experiment was conducted by immerse fibers in 100 ml NaOH solution by a concentration of 2.5%, 5%, 7.5%, and 10% for 2 hours at the room temperature. The specimens were characterized by X-ray diffraction method. The morphology of fiber treated by alkali was observed by Scanning Electron Microscope. The result shows that the crystalline structure of cellulose in Mendong fiber was changed in alkali treatment. It was found that both the degree of crystallinity and crystalline index of Mendong fiber was increased until alkali treatment concentration of 7.5%.