POLYHYDROXYETHER POLYDIMETHYLSILOXANE GRAFT-COPOLYMERS .2. PROPERTIESAND MORPHOLOGY

A series of polyhydroxyether-polydimethylsiloxane (PDMS) graft copolym ers were analysed and tested to determine the effects of factors such as the number-average molecular weight (M(n)BAR) of the PDMS segments, overall PDMS content and nature of the graft linkage on thermal chara cteristics, hydrolytic stability, tensile properties and morphology. D .s.c. measurements showed that the copolymers exhibit two-phase morpho logy even at very low PDMS M(n)BAR (< 1000 g mol-1). Despite the prese nce of the silyl ether linkage, such copolymers display quite good hyd rolytic stability. When the PDMS M(n)BAR is in the region of 5000 g mo l-1, changes in the overall composition have only a marginal effect on thermal stability.