Studies on the nature of the unusually high bulk viscosity of flame retardant prepolymer from cardanol

Abstract

Phosphorylated prepolymer of cardanol exhibits unusually high bulk viscosity (200,000-250,000 cP) at 29°C. The viscosity undergoes drastic reduction with increase in temperature reaching a very low value of 82 cP at 150°C. The intrinsic viscosity of the oligomers has been studied in a number of solvents differing in polarity. The IR spectra of neat solution shows a broadening and shift in the P = O stretching absorption band at 1250 cm^-1 with respect to spectra in CCl₄. These data indicate that presence of hydrogen bonding is probably responsible for the unusually high viscosity exhibited by the system at ambient temperature.