Walter Heckmann

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

Abstract The high temperature application of styrenic polymers was extended beyond the glass transition temperature of amorphous PS by the two following modifications: 1. Increasing the syndiotactic portion, producing crystallites, which act as physical cross-links in the temperature region between the glass transition 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 improved by rubber modification, by which the initiation and stabilisation of the deformation processes—mostly voiding and crazing—are enhanced. Due to the higher stiffness of the molecules in S/DPE and the mutual interaction between the propagating crazes and the crystalline lamellae in sPS, the rubber toughening in these two types of products is likely to be reduced compared to an amorphous PS.

The influence of wettability on the morphology of blends of polysulfones and polyamides

Abstract In this paper we are presenting structural investigations on the phase separation behaviour of a novel high temperature stable polymer blend of a polysulfone (PSU) and a perfectly amorphous polyamide (PA). The phase separation kinetics of thin films cast onto glass slides and of bulk samples was observed by means of various microscopic methods such as optical, laser scanning confocal, scanning electron and transmission electron microscopy. The phase separation process was found to be suppressed by adding a small amount of compatibilizers such as chemically modified PSU, i.e. introducing a small amount of carboxylic groups, which causes the formation of covalent bonds with the PA at the interface of the PSU and PA or by adding a third component, phenoxy, which is supposed to be mainly located at the interface of the PSU and PA and to freeze the phase separation due to its attraction to both the PSU and PA.