Abstract

Polypropylene (PP) is one of the most widely used engineering polymers. In this study, multiwalled carbon
nanotubes (MWCNT) 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 into standard tensile and flexural test specimens,
conforming to ASTM specifications, using a 50 Ton injection moulding machine. The tensile strength increased
marginally with addition of MWCNT, while there was a 30% increase in the flexural strength when compared to
pure PP. The flexural modulus increased from 1470 to 2150 MPa, resulting in increased flexural stiffness of
45%. The presence of MWCNT hinders the crack propagation resulting in improved strength and stiffness. The
melt flow index also showed a drastic drop from 11 gm/10 min to just 2 gm/10 min, which could be attributed to
the increase in viscosity due to stiff MWCNT phase in PP matrix.