Effect of Trolamine and Dibutyltindilaurate on the Structure and Properties of Polyurethane-imide Foams

Polyurethane-imide foams are prepared from polyphenyl polymethylene polyisocyanates, pyromellitic dianhydride and castor oil in presence of trolamine and dibutyltindilaurate catalysts. FTIR spectra proves the successful preparation of polyurethane-imide foams in prepolymer method. The investigation on catalytic mechanism shows that trolamine and dibutyltindilaurate are effective in promoting blowing and gelling reaction, respectively, so trolamine and dibutyltindilaurate are identified to be blowing catalyst and gelling catalyst, respectively. With the fixed amount of trolamine, the density and compressive strength of the resulting foams are enhanced with the increase of dibutyltindilaurate, but average cellular diameter and open cell contents are reduced. Similarly, with the fixed amount of dibutyltindilaurate, open cell contents of the resulting foams are enhanced with the increase of trolamine, while the density, compressive strength and average cellular diameter decreased. Thus PUIFs with variable properties can be prepared through changing the kind and ratio of mixed catalysts.