Y.J. Phua

Poly(butylene succinate)/ Organo-montmorillonite Nanocomposites: Effects of the Organoclay Content on Mechanical, Thermal, and Moisture Absorption Properties

Organo-montmorillonite (OMMT)-filled poly(butylene succinate) (PBS) nanocomposites were prepared by a melt mixing process with internal mixer, at various loading levels (i.e., 2—10 wt%) of OMMT. The effects of clay loading towards the mechanical and thermal properties were investigated through various characterizations such as melt flow index (MFI), density, mechanical tests, X-ray diffraction (XRD), transmission electron microscope (TEM), heat deflection temperature (HDT), and differential scanning calorimetry (DSC). The 2 wt% OMMT-filled PBS gave the highest strength among the rest due to higher degree of exfoliation of layered silicates in PBS matrix. Further increment in OMMT loading had reduced the strength of nanocomposites, which believed to be the result of agglomerations. This can be further confirmed by XRD and TEM. However, increment in clay loading had enhanced the modulus of nanocomposites. Higher OMMT loading tends to give higher melt viscosity because of the presence of clay particles. Moisture absorption at different conditions was performed. The results showed that higher OMMT loading and moisture level tend to increase the overall moisture uptake and also the diffusion coefficient.

Injection Molded Short Glass and Carbon Fibers Reinforced Polycarbonate Hybrid Composites: Effects of Fiber Loading

Hybrid composites of polycarbonate (PC) reinforced with short glass fibers (GF) and short carbon fibers (CF) were prepared by twin-screw extrusion and injection molding techniques. Composites were produced in different ratios of GF and CF by maintaining the total fiber loading at 40 wt%. The mechanical properties such as tensile, flexural strength, and impact of these composites were investigated. It was noted that an increase in GF content led to a higher strength of the hybrid composites as compared to CF. Morphological analysis by using scanning electron microscope reveals that CF had poor fiber-matrix interactions with PC, which brought about the decrement of stress-transfer efficiency. A poor fiber-matrix interaction is believed to be the main cause of the lower strength enhancement by CF than expected. Heat deflection temperatures of composites increased with the increment of GF content. From dynamic mechanical thermal analysis, high-storage modulus is observed at the temperature below Tg. Meanwhile, it was observed that surface and volume electrical resistivity decreased by increasing the CF content owing to its conductivity.

Effect of Heat Treatment on Properties of Kenaf Fiber Mat/Unsaturated Polyester Composite Produced by Resin Transfer Molding

This study investigated the effect of heatingtime during heat treatment on mechanical and physical properties of the kenaf fiber and its composites. Kenafbast fibers were modified by heat treatmentat 140°C for2.5, 5, 7.5, 10 and 12.5 hours. Composites were fabricated by resin transfer molding process with unsaturated polyester as matrices and needle-punched kenaf fiber mat as reinforces. The fiberswerecharacterized by Fourier Transform-Infra Red (FT-IR) and X-Ray Diffraction (XRD). FT-IR resultsshowedthe changesin intensity ofhemicelluloce wavelength (1736 cm-1). Besides XRD observation also confirmed the increase of cellulose content in kenafthat described to the increase of crystallinity index ofkenaf fiber with heat treatment. The single fiber strength investigation stated that the highest strength and modulus was obtained bykenaf fiber heated for10hours indrying oven. SEM observation showed the decreasing numbers of impuritieson thefibers surface with fiber treatment compared to untreated kenaf fibers. The flexural properties of composites showed a similar trend to fiber strength, but the fracture toughnesshas showedcontrary results.