Migration induced localization of multiwalled carbon nanotubes in PP phase of PP/ABS blend and their hybrid composites: Influence on mechanical and thermal properties

Abstract

Carbon black (CB) and multiwalled carbon nanotubes (MWNTs) reinforced 80/20 (wt/wt) polypropylene (PP)/acrylonitrile butadiene styrene (ABS) blends and its composites in presence of dual compatibilizer are processed using twin screw extruder followed by injection moulding. The two-step processing is adopted to disperse the MWNTs and CB in 80/20 (wt/wt) PP/ ABS blends in presence of dual compatibilizer. Initially, MWNTs are dispersed with ABS using melt-mixing followed by addition in PP matrix in presence of CB and dual compatibilizer using melt-mixing. A solution experiments is performed to selectively etch the PP and ABS phase respectively show the migration of MWNTs in the PP phase; and CB is localized in the PP phase. Scanning electron microscope (SEM) observation revel the formation of matrix-droplet morphology for MWNTs and CB in 80/20 (wt/wt) PP/ ABS blends and its composites in presence of dual compatibilizer. The average droplet diameter (Dd) measured using SEM images shows decrease in Dd values with the incorporation of MWNTs and CB in 80/20 (wt/wt) PP/ ABS blends and its composites in presence of dual compatibilizer along with calculated interparticle distance (ID) as compared to pure blend. Differential scanning calorimetry (DSC) studies shows the percent crystallinity (Xc) and lamellae thickness of MWNTs and CB filled 80/20 (wt/wt) PP/ ABS blends and its composites in presence of dual compatibilizer increases as compared to pure blend. The tensile properties increases significantly for MWNTs and CB filled 80/20 (wt/wt) PP/ABS blends and its hybrid composites in presence of dual compatibilizer due to the refined morphology and increase in crystallinity. In addition, the thermal stability is enhanced significantly for the selectively localized MWNTs and CB in PP phase of 80/20 (wt/wt) PP/ABS blends and its composites in the presence of dual compatibilizer as compared to pure blend established using thermogravimetric analysis (TGA). The composition of 2.5 wt% of CB filled 80/20 (wt/wt) PP/ABS blends and its composites in presence of dual compatibilizer and MWNTs is the optimized concentration to achieve the highest enhancement in tensile properties, crystallinity, morphology refinement and thermal stability.