Thermal Graft Copolymerization of Styrene with Rubber. IV. The Peculiarities of the Process of Producing High Impact Polystyrene by Means of Continuous Methods

Realization of styrene copolymerization with rubber by a continuous method brings diminishing of the rubber efficiency. The reason for it is deterioration of the product morphology — reducing of specific volume of the rubber phase, lowering of number of polystyrene occlusions in rubber particles, and increase of dispersion of rubber particles according to sizes. Change of morphology of HIPS continuously is caused by introduction of fresh rubber solution into the concentrated polymer to which there are no phase inversion possible: in the lesser volume the degree of grafting of polystyrene to rubber takes place. Diminishing of the content of graft copolymer deteriorates conditions of occlusions forming in the course of the process and the lesser degree of crosslinking of rubber deteriorates the strength of rubber particles and diminishes residual internal microtensions in the obtained product.