Investigation of the mechanical and electrical properties of polypropylene - talc composites

Abstract

Polypropylene (PP) and PP-talc composites with compositions of9'1, 8:2, 7:3, 6:4, and 5:5 wt, ratio were prepared by extrusion Cumcompression molding methods, Surface morphology of the composites wag observed by a scanning electilln microscope (SEM) Various properties such as bulk density, water absorption, tensile strength, flexural strcngth, Young modulus, microhardness and electrical properties of these composites were investigated SEM micrographs ofPP and PP-tale composites show that illuglmess of the surface of the composites gradually increases as the amount of talc increases. The bulk density of the composites decreases with the increase of talc content. With the increase of the percentage of talc and period of immersion, the water absorption increascs The tensile strength and elongation-at-break (%) of PP-talc composites decrease with the increase of talc content whereas Young moduli.!s(YM) of the composites increases with talc content. The YM value of the composites with JOwt% tale is the highest. The flexural strength increases with the addition of talc up to 30wt% and after that it decreases but flexural break (%) decreases with the increase of talc content. Flexural modulus increases slowly up to 20wt% talc and then it increases rapidly for JOwt% talc. With the increase of talc content, the microhardness (H) value increases up to JOwt%talc and after that it decreases for PP- talc composites. The thermal bchavior ofPP-talc composites was analyzed by TGA, Dr A, and DTG It is seen that composites become thermally more stable than the neat PP, The current-voltage (I-V) charactenstics of the composites wer'e recorded in the voltage range from 0 to 120 V DC at different temperatures. It is evident that currem-voltage curves show ohmic behavior in the lower voltage region. Conductivity has been calculated and is found to incrcase with increasing temperature but with the increase % of talc, conductivity decreases for PP-talc composites, The activation energy of all the samples has higher value in high temperature region than those at low temperature region