Tensile behaviour of MWCNT and CNP filled polypropylene thermoplastic composites

Abstract

Most of the house hold articles and devices which we use in everyday life is made of Natural polymers and synthetic polymers. Polypropylene (PP) is one of the most widely used engineering polymers. Existing research reports that polymer nano-composites show far better performance versus micro-fillers. In this study, multiwalled carbon nanotube (MWCNT) and carbon nanopowder (CNP) were melt blended into PP in the ratio of 2.5, 5 and 10 wt% using twin screw extrusion process. The extruded pellets were then injection moulded using a 50 Ton injection moulding machine to produce PP + CNP and PP + MWCNT composite flat test specimens according to ASTM standards and were used to carry out the tensile tests. While there is a reduction in failure strain and a marginal increase in ultimate tensile strength, there is 25% increase in young’s modulus with CNP whereas it nearly 65% with MWCNT as reinforcement. Failure strain is found to be dropped drastically by 54% with CNP and 64% with CNT. These experimental values were compared with the theoretical values calculated using Halpin-Tsai model for randomly oriented fibres. While the theoretical and experimental data in case of PP + CNP were in very good agreement, in case of PP + CNT there was significant deviation. The inter layer load transfer in case of MWCNT being very weak forces only the outer layer to contribute to share the load with matrix which is the cause for the deviation. The comparison and analysis of theoretical and experimental results are carried out in the present work which are found to be by the previous research findings.