PHASE-SEPARATION IN SEGMENTED POLY(URETHANE UREA) COPOLYMERS DURING REACTION INJECTION-MOLDING (RIM) POLYMERIZATION

In situ experiments were performed with a portable RIM(reaction inject ion molding) minimachine interfaced to an FTIR spectrophotometer to fo llow the reaction chemistry and monitor phase separation of copoly(ure thane urea)s during RIM polymerization. The PUU copolymers were based on ethylene oxide-capped poly(propylene oxide) polyether diol, 3,5-die thyltoluenediamine (DETDA), and uretonimine liquefied 4,4'-diphenylmet hane diisocyanate. The effect of catalyst concentration on the degree of phase separation in the as-molded RIM PUU copolymers was investigat ed by using differential scanning calorimetery and scanning electron m icroscopy as supplementary methods. The results suggested that an incr ease of degree of phase separation and a decrease of the size of hard- segment-rich domains take place with a rise of catalyst concentration. The morphological feature was a consequence in combination with the i ncrease in relative rate of urethane formation and the ordering of hyd rogen bonding through urea groups. (C) 1997 John Wiley & Sons.