Preparation of core-shell structured polymer and its application in toughening polystyrene

The authors prepared a kind of core-shell structured polymer from n-butyl acrylate and styrene via seed emulsion polymerization, and studied the effect of mass ratio of core to shell monomer on emulsion polymerization process. The result verifies that the total conversion of the monomers exceeds 98%. On the assumption that the latex particles present and grow in the shape of sphere, the theoretical particle diameter of the latexes is consistent with the actually measured value; the fact reveals that there exists no significant secondary nucleation in the polymerization system. As the mass ratio of core to shell monomer rises, no obvious variation in glass transition temperature (T_g) of the low temperature zone [poly(n-butyl acrylate) zone] appears while a declining trend in T_g of high temperature zone (polystyrene zone) occurs. This phenomenon demonstrates the existence of the transition layer formed on the interface of the core-shell structure. When blending the emulsion polymer with polystyrene (PS), the impact strength of the blending increases at first and decreases with that as the mass ratio of core to shell monomer augments, that means there are optimum conditions suitable for toughening PS with the core-shell structured polymer.