Preparation and properties of polydimethylsiloxane-modified epoxy resins

In this work, polydimethylsiloxane (PDMS) with different molecular weight w ere used to modify diglycidyl ether of bisphenol A (DGEBA). A PDMS-block-DG EBA. copolymer that acted as a compatibilizer was prepared via DGEBA, hydro xy terminated PDMS, and silane coupling agent in the presence of a catalyst . The reaction mechanisms and compatibilizing effects of the block copolyme r were studied by means of Fourier transform infrared (FTIR) spectrum analy sis and observation under scanning electron microscopy (SEM). The thermal a nd mechanical behaviors were analysed as well. Results indicated that the b lock copolymer has good compatibilizing effect, and PDMS with low molecular weight could be dispersed in the DGEBA matrix more evenly. Moreover, the P DMS modified DGEBA systems had higher impact strength and lower weight loss rate than those of the pristine DGEBA system. (C) 2000 John Wiley & Sons, Inc.