DYNAMICS OF (MICRO)PHASE SEPARATION DURING FAST, BULK COPOLYMERIZATION : SOME SYNCHROTRON SAXS EXPERIMENTS

The evolution of (micro)phase separation during the bulk formation of a segmented copolyurethane based on 4,4'-diphenylmethane diisocyanate, 1,4-butanediol and on a poly-(oxyethylene-block-oxypropylene) diol of molar mass 2000 was followed using a small RIM machine. Generally, higher polymerization temperatures led to a faster rate of (micro)phase separation but a lower ultimate degree of (micro)phase separation. An induction time was observed that decreased with increasing temperature. The scattered intensity at fixed angle increased with the square of time, and the length scale in the material increased with temperature