COMPREHENSIVE STUDY OF THE OXIDATIVE-DEGRADATION OF AN EPOXY-RESIN USING THE DEGRADATION FRONT MODEL

This work shows (using the invariant kinetic parameter (IKP) method an d a computation of the distribution of probabilities associated with k inetic functions) that the main degradation step of a model epoxy resi n TGDDM/DDA is described by two different kinetic models (reaction ord er and potential law). Then, the study using the cone calorimeter (hea t flux: 50 kW/m(2)) allows for kinetic data to be obtained under the c onditions of a fire and for the computation of the degradation front t emperature. Comparison of the values of this temperature and of the te mperature measured in the lowest volume of the sample allows for a pro posal of widespread degradation in the whole of the sample when the de gree of conversion alpha > 0.6. The relationship between the values of the rate of heat release (rhr) and the rate of mass loss (dm/dt) vers us alpha suggests three successive steps: an abrupt flaming of the mat erial with formation of the carbonaceous material (alpha < 0.15; no si mple relation between rhr and dm/dt); a degradation of this material ( steady state for 0.15 < alpha < 0.65: rhr/ (dm/dt) is a constant, the lower material being protected from the heat flux); and finally, compe tition between the degradation of the carbonaceous material and the de gradation (glowing) of the resulting high temperature residue. (C) 199 6 Published by Elsevier Science Limited