THERMAL-BEHAVIOR OF POLYAMIDE-6-BASED INTUMESCENT FORMULATIONS - A KINETIC-STUDY

We have studied the thermal and thermooxidative degradation of polyami de-6 (PA-6), PA-6/ammonium polyphosphate (APP) and PA-6/ethylene-vinyl acetate 8% (EVA8)/APP blends and shown the influence of oxygen in the degradation mode. The invariant kinetic parameters (IKP) method allow s us to model the degradation. It shows that APP decreases the stabili ty of the virgin polymer and implies a protection mechanism via an abl ative process. Moreover, it explains the role of EVA8 in the improveme nt of the fire behaviour of the blends; it allows the reduction of fue l flow rate feeding the flame. Modelling also allows a comparison betw een different intumescent polymer systems in order to show the differe nt mechanisms leading to the intumescence phenomenon. (C) 1997 Elsevie r Science Limited.