CURE KINETICS OF POLY NITRATOMETHYL OXETANE WITH DIFFERENT ISOCYANATES STUDIED BY DIFFERENTIAL SCANNING CALORIMETRY

摘要

This paper reports cure kinetics of poly nitratomethyl oxetane (PLN) with different isocyanates like isophorane di-isocyanate (IPDI) and hexamethylene di-isocyanate (HMDI). Reactions were monitored by differential scanning calorimetry (DSC) in the presence of two different cure catalysts namely di butyl tin di laurate (DBTDL) and ferric tris acetyl acetonate (FeAA) and their effect on the cure reaction was studied. Cure kinetics was evaluated using the multiple heating rate Ozawa method. The reactivity of two isocyanates and catalytic efficiencies were determined based on DSC reaction temperature, activation energy, and rate constants. Based on cure temperatures, FeAA catalyzed reactions have lower cure temperature than DBTDL catalyzed reactions, inferring that FeAA is a more active catalyst for PLN cure reactions. Rate constants (k) of FeAA catalyzed PLN cure reactions were higher than of DBTDL catalyzed reactions. The values of activation energies (Ea), pre-exponential factor, and rate constant also support the same trend. Completion of the curing process was monitored with the help of Fourier transform infrared. Viscosity buildup was measured with the help of rheometer by taking curing profiles for each system at 30° C and it followed the similar trend as determined by DSC.