Rubber toughening of syndiotactic polystyrene and poly/(styrene/diphenylethylene)

The high temperature application of styrenic polymers was extended beyond t he glass transition temperature of amorphous PS by the two following modifi cations: 1. Increasing the syndiotactic portion, producing crystallites, which act a s physical cross-links in the temperature region between the glass transiti on and the melting point. 2. Copolymerisation with DPE leading to an increase in the glass transition temperature with increasing DPE-content. In both materials crazing prevails. Toughness has been successfully improve d by rubber modification, by which the initiation and stabilisation of the deformation processes-mostly voiding and crazing-are enhanced. Due to the h igher stiffness of the molecules in S/DPE and the mutual interaction betwee n the propagating crazes and the crystalline lamellae in sPS, the rubber to ughening in these two types of products is likely to be reduced compared to an amorphous PS. (C) 2000 Elsevier Science Ltd. All rights reserved.