Effect of bismuth-containing catalysts on HTPB curing kinetics

Effect of triphenyl bismuth(TPB)and tri (exhoxyphenyl) bismuthine(TEPB) on kinetics of hydroxyl terminated polybutadiene-toluene diisocyanate(HTPB-TDI) curing reaction were studied by non-isothermal differential scanning calorimetry(DSC). Characteristic temperature of curing systems were measured for calculating kinetic parameters by Kissinger and Crane method and the curing reaction kinetic equations was established. Results show that catalysts decrease the curing temperature and shorten the curing temperature gradient. Activation energy(E_a) of uncatalyzed HTPB-TDI curing system is 51.29 kJ·mol^-1, the E_a of HTPB-TDI are decreased to 46.43 kJ·mol^-1 and 40.14 kJ·mol^-1 by using TPB and TEPB. Both catalysts lower reaction temperature and curing time through decreasing activation energy of curing reaction and accelerating reaction rate. The reaction rate constant value of HTPB-TDI catalyzed by TEPB at 34℃ is similar to that of HTPB-TDI catalyzed by TPB at 50℃, indicating that the catalytic activity of TEPB is higher than that of TPB and it's available for ambient catalyst.