Obtaining kinetic parameters of polyamide imide reaction

A kinetic study for the synthesis of polyamide-imide (PAI) is presented, determining the instantaneous intrinsic viscosity [eta] at different reaction times, in order to assess the influence of the order of addition in the reactants 1,2,4-benzenetricarboxylic anhydride (TMA) and diphenylmethylene diisocyanate (MDI) on the chemical structure and on the thermal properties of PAI. The kinetic parameters determined were the reaction order, n, the constant rate, k, and the activation energy, E-a . The reaction was carried out at different temperatures from 110 to 150 degrees C at 30 % solids in N-methyl-2-pyrrolidone (NMP) as solvent. The chemical structure of the polymer was determined by H-1-NMR, FTIR and elemental analysis; other properties such as the glass transition temperature (T-g), onset temperature of weight loss rate (T-0) and temperature of maximum weight loss rate (T-max) obtained by DSC and TGA/DSC were used to explain the most likely distribution of arrangements II, AA and AI along the chain of PAI based on thermal stability.