Abstract
The physico-chemical interaction between hydrophobic polyolefin materials and originally hydrophilic inorganic nano-particles like surface hydroxylated SiO2 has not been well understood up to now. In this study, the influences of particle size, content of hydrophilic SiO2 nanoparticles on the isothermal growth rate of polypropylene (PP) spherulites in various PP/SiO2 nanocomposites were investigated by polarized optical microscope equipped with temperature controlled hot stage. Moreover, photo-oxidative degradation behavior of the PP/ SiO2 nanocomposites were investigated. It is most interesting to note that the addition of smaller SiO2 nanoparticles effectively lowered the growth rate of PP spherulites in the composites and the spherulite growth rate became zero for the PP/16nm-SiO2 nanocomposites with the SiO2 content above 2.5 wt%. It was found that the sample without spherulite morphology is more stable to photo-degradation. Spherulite structure is considered to have the influence affect photo-oxidative degradation.
