Modification of epoxy resin by isocyanate-terminated polybutadiene

Hydroxy-terminated polybutadiene was functionalized with isocyanate groups and employed in preparation of a block copolymer of polybutadiene and bisph enol A diglycidyl ether (DGEBA)-based epoxy resin. The block copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy and size-ex clusion chromatography (SEC). Cured blends of epoxy resin and hydroxy-termi nated polybutadiene (HTPB) or a corresponding block copolymer were characte rized by differential scanning calorimetry (DSC), dynamic mechanical analys is (DMTA), and scanning electron microscopy (SEM). All modified epoxy resin networks presented improved impact resistance with the addition of the rub ber component at a proportion up to 10 wt % when compared to the neat cured resin, The modification with HTPB resulted in milky cured materials with p hase-separated morphology. Epoxy resin blends with the block copolymer resu lted in cured transparent and flexible materials with outstanding impact re sistance and lower glass transition temperatures. No phase separation was d iscernible in blends with the block copolymer. (C) 2002 John Wiley & Sons, Inc. J Appl Polym Sci 83: 838-849, 2002.