Research On Polypropylene/Modified Nano-silica Composites

Nano silica/polypropylene composite was widespread concerned due to its excellent features.Nano silica was fully effective in the matrix as it dispersed uniformly and formed a stable interface layer with matrix.This paper was to reduce the surface energy of nano silica by surface modification and prepare excellent performance nanocomposites.Two-step method was used to modify the nano silica in order to achieve its surface functionalization.First of all,the influences of coupling agent KH-570 concentration,reaction time,temperature and solvent on the grafting yield were investigated.The results showed that the optimal conditions for the first modification of nano silica was that the mass ratio of nano silica to coupling agent KH-570 1 to 0.8,reflux 6h in ethanol-water,and alkylation nanoparticles grafted was about 23%.Glycidyl methacrylate and styrene as monomer polymerized with alkylation nanoparticles in toluene.Using orthogonal test to determine the influence of various factors on the monomer grafting rate,and reaction conditions were optimized by the single factor experiment.The results showed that the facters order from the primary to the time:the dosage of initiator,monomer concentration,reaction temperature and reaction time.The initiator 6%(wt),monomer 0.4 mol/L,reaction for 2 hours at 85 ? gained the modification of nano silica graft rate about 40%.FTIR results showed that coupling agent and monomer were successfully grafted to the surface of nano silica particles.And grafting ratio was measured by weight loss method.Nano silica Polypropylene composites were obtained in twin screw extruder.The effects of nano particles content and compatibilizer content on the mechanics properties,vicat softening temperature and melting behavior and mass flow rate measurement were studied.The measure results showed that modified nano silica particles could improve the comprehensive performance of polypropylene,and compatilizer could improve the comprehensive performance of composite materials further.The compatibilizing effect of multi-monomer compatilizer was better than the single one.