Abstract: Polypropylene (PP)/nano-SiO2 composites were prepared by melting blending, and their condensed structure was investigated by means of polarized light microscope and differential scanning calorimetry. The results indicated that incorporation of nano-SiO2 particles not only enhanced the crystallinity of PP but also decrease the size of spherulites along with a fuzzy boundary. As a result, the crystallization temperature and melt temperature increased by 6.5 % and 2.6 %, respectively. Moreover, the presence of KH-560 silane coupling agent and maleic anhydridegrafted PP enhanced the compatibility between nano-SiO2 particles and PP matrix. This leads to an improvement in interfacial adhesion and a better dispersion of nano-SiO2 particles in the matrix, thus resulting in an increase in impact toughness by 40 %.

Key words: polypropylene, nano silicon dioxide, condensed state structure, compatibility, crystallinity