Study on the Reaction of TDI and PPG with Organo-Tin Mixed Catalyst

The study of polyurethanes are of continuing interest due to their excellent physical properties. In his study, the reaction kinetics and polymerization conditions in two-step process of toluene diisocyante (TDI) and polypropylene glycol (PPG) with organo-tin mixed catalyst were investigated by di-n-butylamine back-titration. It was showed that the reaction obeyed the second-order equation of step-growth polymerization, the rate constants of TDI and PPG reaction at 50, 60 and 70 degrees C were 0.0922, 0.3373 and 0.5828 kg. mol(-1).min(-1), respectively. The activation energy obtained from the result was 71.63 kJ.mol(-1). The number average molecular weight (Mn) and molecular-weight distribution (Mw/Mn) of the polyurethane were 45175 and 1.53, respectively, and the content of hydrogen bonding in the N-H group from Fourier transform infrared spectrum (FTIR.) was 80.75%, which manifested that the large amount of N-H were present in hydrogen bonding.