Study On Preparation Of Core-shell Organosilicon Particles And Modification Of PVC Resin

In this paper, core-shell polysiloxane/polyacrylate particles were synthesized by seeding emulsion polymerization method. It presented great superiority and could be utilized as biomaterial, coatings, adhesives, and many other materials due to their combined excellent performance. The preparation, structures and properties of core-shell polysiloxane particles were studied. The main results were summarized as follow:1. Silicon rubber emulsion was prepared by pre-emulsion. The influence of pre-emulsification time, concentration of H2SO4 catalyst and concentration of emulsifier sodium dodecylbenzene sulfonate (SDBS), reaction temperature and the mol ratio of D4/TEOS on the kinetics of the reaction were investigated. The results showed that the finally conversion of D4/TEOS increased with the increasing of the time of pre-emulsification, and the rate of the copolymerization of D4/TEOS was promoted when the reaction temperature raised and the concentration of catalyst or emulsifier increased. The rate of the copolymerization was accelerated and the time of equilibrium become shorter with the increasing of TEOS. The apparent reaction order for sulfuric acid, emulsifier and TEOS was 0.42, 0.38 and 0.27 respectively. The total activation energy of the copolymerization of D4/TEOS was 14.67kJ/mol. The particle size was determined to SDBS and TEOS. The results demonstrated that the average that diameter of the latex particles decreased with the increment of the SDBS concentration, while increased with the increment of TEOS. The crosslinking density may be regulated with the amount of TEOS.2. PSi/PMMA core-shell particles had been synthesized with PSi latex as core and PMMA for shell. The polymers structure were analyzed by FT-IR, DSC and TEM. The influence to the core-shell polymer of dropping rate of MMA monomer, SDBS content and coupling agent MPS content during the course of preparation were studied. The result indicated that excellent core-shell structure can be obtained with the reducing of the dosage of SDBS and the dropping speed of MMA monomer. The formation of core-shell PSi/PMMA was based on the embedding mechanism.3. A series of PSi/PMMA core-shell particles were prepared. The relation between the toughening effect of PVC and the size of PSi core, crosslinking degree, MPS content, core/shell monomer mass ratio, resins ratio were researched. The results showed that the optimal PSi particle size was 90nm, monomer mass core/shell ratios was 1/2. MPS content of 4% and TEOS content of 4-6% was preferable. The toughening mechanism of PSi/PMMA on PVC was investigated by SEM, which indicated that PSi/PMMA core-shell particles were dispersed homogeneously in the matrix of PVC resin, with a typical"sea– island"distribution.4. The multi-layer structure of PSi/PSt/PMMA core-shell particles was prepared by a two-step preparation process. The particles were charactrizaed by FT-IR, DSC, XPS and TEM. The paper's innovations include: The emulsion copolymerization kinetic behavior of D4/TEOS was studied. The multi-layer PSi/PSt/PMMA core-shell particles were prepared with two-step process. The influencing factors of toughening PVC by shell-core PSi/PMMA were studied, and the results have very important significances for the development of PVC resin toughened by core-shell silicone particles.