Nanosilica-Reinforced Polypropylene Composites: Microstructural Analysis and Crystallization Behavior

Polypropylene (PP) was reinforced with polystyrene-grafted nanosilica particles. A detailed study on the microstructure of untreated and treated nano-SiO2-particle–reinforced polypropylene composites has been made by using Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The observations were correlated with the properties of the composites. Characterization of the microstructure of the nanocomposites led to a better understanding of the mechanisms of improvement in properties upon modified nanosilica reinforcement. Dispersion characteristics of the nanoparticles and the extent of agglomerate formation became clear from the AFM and TEM examinations. In order to analyze the nanomechanical properties of the composite, microscratching and nanoindentation studies were carried out using AFM. The effect of particle reinforcement on the crystallization behavior of the composites has been studied. Crystallization kinetics has been analyzed by Differential Scanning Calorimetric (DSC) measurements. The nature of nucleation and crystal growth process has been investigated by optical microscopy. The dynamic mechanical properties, microhardness, and the wear properties of the nanocomposites were examined as a function of filler content.