HTPB-based polyurethanes. II. SINs with PMMA

Simultaneous interpenetrating networks from poly(methyl methacrylate-co-eth yleneglycol dimethacrylate) (PA) and a hydroxyl-terminated polybutadiene-ba sed polyurethane (PU) were prepared with various hard-segment contents (X) in the PU and different ratios (PU/PA) between the components. The level of the reinforcement, the mechanism of molecular failure, and the phase inver sion depended strongly on X. Dynamic mechanical results indicated that the interpenetration occurred in the rigid blocks of the PU. The improved therm al and mechanical properties observed with higher values of X were interpre ted in terms of the molecular weight and polydispersity of the hard blocks in the PU. (C) 2000 John Wiley & Sons, Inc.