Selective crosslinking of the elastomer phase in high-impact polysterene

The mechanism of crosslinking in the elastomer phase of high impact (HIPS) polystyrene is considered and the requirements for the crosslinking initiator are formulated. For elastomers of low reactivity, particularly, the importance of selective dispersion of the initiator in the elastomer phase is indicated. It was shown experimentally that tert-butyl perbenzoate, normally used for crosslinking the diene rubber phase in HIPS, was ineffective for crosslinking HIPS containing a slightly unsaturated silicone as the elastomer phase. Oligodimethylsiloxane with terminal peroxy groups, which is not very compatible with styrene-polystyrene blends but readily compatible with the rubber, was shown to be an effective crosslinking agent. Crosslinking of the elastomer phase was shown to result in a substantial increase in the impact resistance of the material.