Isothermal and anisothermal decomposition of carbon fibres polyphenylene sulfide composites for fire behavior analysis

This work was aimed at studying the influence of severe temperature conditions representative of fire conditions on thermal decomposition of both plain PPS thermoplastic resin and C/PPS laminates. The investigations on the relationship between local temperature resulting from the local balance energy exchange, the local atmosphere and the mass losses are essential in understanding the influence of fire on polymers and polymer matrix composites. This involves first identifying the thermal decomposition phenomena involved by means of thermogravimetric analyses conducted in both isothermal and anisothermal testing conditions, as well as under inert and oxidizing atmospheres. As far the heating conditions (isothermal and anisothermal) are concerned, an increase in the testing temperature leads to increasing decomposition rates, as expected. In anisothermal conditions oxidation starts before the end of pyrolysis, whereas, pyrolysis is complete before oxidation in isothermal conditions. Regarding the influence of fibers on the thermal decomposition mechanisms in PPS-based composites, the cross-linking may be promoted by the presence of fibers resulting in delaying the onset of pyrolysis under oxidizing atmosphere. Such cross-linking is not significant enough to observe such a delay under air. Finally, MT-TGA tests under inert atmosphere seem to reveal three different mechanisms during pyrolysis in agreement with conclusions drawn in the literature on the same material: depolymerization, random chain scission and ultimately cyclisation (char formation).