INFLUENCE OF STRUCTURE OF HYDROXYL-TERMINATED MALEOPIMARIC ACID ESTERON THERMAL-STABILITY OF RIGID POLYURETHANE FOAMS

A series of hydroxyl-terminated maleopimaric acid esters (HTMAEs) and rigid polyurethane (PU) foams based on these HTMAEs were synthesized u sing chemically modified natural gum rosin and its derivative maleopim aric acid as raw materials. Thermal stability of these polyols and the ir corresponding rigid PU foams was studied by a thermogravimetric met hod and a dimensional stability measurement. It was shown that the the rmal stability of the final foams was strongly dependent on the struct ure of their corresponding polyols. The thermogravimetric analysis cur ves of these rosin-based rigid PU foams displayed two distinct regions of weight loss. It has been shown that at the initial stage of weight loss the process was dominated by polyol component degradation; the s econd stage was governed by isocyanate component degradation. (C) 1995 John Wiley & Sons, Inc.