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.