Comparative Study of Polypropylene/Carbon Nanotube Nanocomposites with Various Compatibilizers and Influence on Mechanical, Thermal, Rheological and Morphological Properties

This study investigated the comparative effects of various maleic anhydride-grafted polymeric compatibilizers such as polyethylene-graft-maleic anhydride, polypropylene-graft-maleic anhydride, polyethylene(alt)-graft-maleic anhydride and poly(styrene-ethylene/butylene-styrene)-graft-maleic anhydride on the final properties of polypropylene (PP) carbon nanotube (CNT) composites. Polypropylene nanocomposites (PP-CNT) were prepared by melt mixing using a laboratory scale twin-screw extruder. The mechanical test results showed that the incorporation of CNTs along with various compatibilizers increased the tensile strength (10.3%) and tensile modulus (24.2%). The tensile modulus and yield stress of the PP-CNT nanocomposites were significantly higher than those of the pristine PP. Differential Scanning Calorimetry (DSC) analysis revealed that the addition of CNTs slightly increased the melting temperature of the crystallization peaks. In the compatibilized PP-CNT composites, the CNTs were well dispersed to enhance the onset of degradation and maximum decomposition temperatures. The frequency-dependent rheological behaviors of PP-CNT nanocomposites indicated that the storage modulus (G’), loss modulus (G”), and complex viscosity (η*) PP increased for the compatibilized system. The XRD results indicated that the addition of CNTs and compatibilizers slightly affected the crystalline nature of PP. Scanning electron microscopic images of the fractured surfaces presented in the micrographs showed the brittle nature of the surface morphology of PP-CNT nanocomposites.