Study On Preparation Of Nano-SiO₂/Acrylate Core-Shell Polymer And Its Application In Toughening PVC

We treated by methacryloxypropyltrimethoxysilane(MPS) and y-aminopropyltriethoxysilane (APS) the surface of nano-silica to control and/or manipulation of the surface properties. The composites of nano-silica encapsulated by ACR were prepared. The notched impact strength of PVC can be improved when the composites were blending with PVC in the thesis.The surface of nano-silica was treated by silane coupling agents of MPS and APS. The structure of modified nano-silica was characterized by FTIR, Zeta potentials, TG and TEM. The results showed that the grafting and coating percent on the surface of nano-silica was increased with the content of silane coupling agent of (MPS). The grafting and coating percent reached 35.7% when the content of MPS was 50wt%, pH 4, reaction time 90min. Photographs of TEM showed that the treated nano-silica obtained was dispersed in ethanol more uniform than that of untreated one.Core-shell polymer (nano-silica/ACR) was prepared by seed emulsion polymerization, using nano-silica, MPS-silica or APS-silica as core, and acrylate as shell. The optimum reaction conditions were determined by a series of experiments. The factors that influenced the structure and shape of latex particles were studied.Mechanical properties of core-shell/PVC blends were influenced by nano-silica, the particle size and their distribution of composite latex particles, which resulted in the interface action between silica particle and polymer. The results showed that the latex particles have irregular core-shell morphological structure like sandwich when used nano-silica and APS-silica as core, and stability of placement was bad. MPS-silica synthesized was better dispersed in the PVC matrix than those of nano-silica and APS-silica. The notched impact strength of PVC blends was improved remarkably. The notched impact strength increased above 3 times that of PVC, when the ratio of BA/MMA was 60/40, silica/monomers were 20%, the weight ratio of PVC/MPS-silica was 100/6. And the tensile strength of the blend was decreased only 4%. Because of adding Core-shell polymer, the mobility of the composite resin becomes better than that of pure PVC.The method of centrifugation was used to separate nano-silica/ACR composite latex particles from pure ACR, and the products were characterized by FTIR, TGA. The result showed that the grafting efficiency was decreased, with the concentration of emulsifier increased. Large diameter nano-silica was helpful for reinforcing PVC resin, and the smaller particle was fortoughening PVC.