Emulsion Polymerization Modified Polystyrene And Application Of Its Composite

In this paper, the kinetic of emulsion polymerization of poly(styrene-butyl acrylate) modified by nano-silica has been studied, on the basis of studying the dispersion of nano-silica. The inserting method and properties of the composite materials in consist of OMT and poly(styrene-butyl acrylate) had been researched; the ultra-fine organic rigid particles crosslinked polystyrene (XPS) has been synthesized by emulsion polymerization, the effect of the synthesis process on the size of organic rigid particles was discussed. The cause of the increasing mechanical properties of PP composite materials, which were strengthened and toughened with organic rigid particles and elastomer, had been investigated .The results of studying viscosity and precipitate height of SiO2 nano-particles suspension showed that the SiO2 nano-particles are very good dispersed by DP270 or CAT 639W dispersant. The viscosity of the suspension reduces from 35.1mPa-s to 23.3mPa-s at 0.2%(wt) DP270, and from 35.1mPa-s to 23.1mPa-s at 0.4%(wt) CAT 639W. The kinetic study found that the SiOi nano-particles reduced the reaction rate of emulsion polymerization. The effect factors of polymerization conversion rate, such as the system of emulsifier, temperature, initiator, surface treatment and the content of SiO2 nano-particles, were discussed.The OMT after its suspension treated with ultrasonic wave was inserted with poly(styrene-butyl acrylate) emulsion. XRD test found the layers of OMT particles were dispersed partly in the composite; Extraction experiment of nano-OMT/PBA-St composite indicated a great amount of macromolecule has inserted into the interlayer of OMT. DTA analysis showed the decompose temperature of composite hasimproved by 73 at 4% OMT.The data of mechanical properties test proved that the composite materials compounded with 0.39~0.46um PS organic rigid particles at 0.2%(wt) and PP have excellent strength and toughness. SEM photograph found that the organic rigid particles were separated into 60~80nm size in the composite by melting process, which has belter toughness compare with the PP compounded with ultra-fine organic rigid particles.The charpy notched impact strength of the PP composite materials toughened with organic rigid particles and SBS elastomer has heightened by about 120% compared with that of pure PP, and this fact knows that the organic rigid particles and SBS elastomer have cooperate action in toughening PP. Polarization microscope had observed that the size of sphere crystal of PP after adding organic rigid particles became smaller, the excellent compatibility of interphase between matrix and organic rigid particles in composite has been proved, and the organic rigid particles were drew out into cavities from matrix in the photograph of the impact breaking section by SEM. The reason of enhanced toughness of the composite is that the material absorbed amount of energy at forming cavities, which is the mechanism of the PP composite toughened with the organic rigid particles.