INFLUENCE OF THE COMPOSITION OF ROSIN-BASED RIGID POLYURETHANE FOAMS ON THEIR THERMAL-STABILITY

A series of rosin-based rigid polyurethane foams of different composit ion were synthesized directly from chemically modified gum rosin. The effect of the composition of these rosin-based rigid polyurethane foam s on their thermal stability and compression strength was measured. It was shown that the onset temperature of weight loss and the dimension al stability at high temperature increased with increase of the molar ratio of NCO/OH. The TGA data further confirmed that the second stage weight loss in the two-stage weight loss process of these polyurethane foams was governed by thermal degradation of the isocyanate component . Although density had no significant influence on the TCA curves of t he rosin-based rigid polyurethane foams, it had great influence on the dimensional stability at high temperature and compression strength of the foams. It has been shown that the inclusion of rosin in rigid pol yurethane foams increases the strength and thermal stability compared with that of polyether-based ones. (C) 1996 John Wiley & Sons, Inc.