Effect of Reinforcement on Tensile Behavior of MWCNT Filled Thermoplastic Composites

Polypropylene (PP) is one of the most widely used engineering polymers. In this study, multiwalled carbon nanotube (MWCNT) has been melt blended into PP using twin screw extrusion process, indifferent ratios for two different set of composites. For first set, 2.5, 5 and 10 wt.%of MWCNT was used whereas for another set 1.25, 3.75 and 7.5% were the values. The extruded pellets were then injection moulded using a 50 Ton machine to produce PP+MWCNT composite flattest specimens according to ASTM standards and were used to carry out the tensile tests. While there is a huge reduction in failure strain and a marginal increase in ultimate tensile strength, there was nearly 65 % increase in young’s modulus with MWCNT as reinforcement. These experimental values were compared with the theoretical values calculated using Halpin-Tsai model for randomly oriented fibres.There was significant deviationof the theoretical data from the experimental data. The comparison and analysis of theoretical and experimental results are carried out in the present work. A mathematical model equation has been fit for the variation of young’s modulus in both the sets of composites. The variation has been found to be constant in terms of the parameters of the equation. This shows the variation of the tensile properties are proportional to the degree of reinforcement. Keywords—Polypropylene, carbon-nanotubes, twin-screw extruder, nano-composites, Halpin-Tsai.