VAPORIZATION EFFECTS IN EVALUATION OF DECOMPOSITION KINETIC-PARAMETERS BY HIGH-PRESSURE DSC

Conventional analysis of High-Pressure DSC (HPDSC) data gives only app roximate values for the onset temperature of decomposition and the dec omposition kinetic parameters because the data are masked by vaporizat ion effects. A model is proposed to calculate High-Pressure DSC heat f low data under conditions wherein both decomposition and vaporization occur simultaneously. The vaporization effects are modelled using a si ngle mass transfer parameter. Experiments were carried out to show tha t the parameter, once evaluated from data at a slightly higher pressur e, could be used to estimate vaporization effects at even higher press ures. A method is suggested for determining the true kinetic parameter s of decomposition.