Thermal kinetics study and flammability evaluation of polyimide fiber material

Abstract

The thermal stability and flammability of polyimide (PI) fiber for fire protection applications have been assessed by dynamic thermogravimetry and microscale combustion calorimetry (MCC) measurements, respectively. The polymer decomposed in a single step and main pyrolysis occurs within a very narrow temperature range. The kinetic analysis of the main pyrolysis process was conducted by a composite procedure involving the iso-conversional method and the Master-plots method. The main process reaction mechanism of the polyimide obeyed random nucleation model with three nuclei on the individual particle. Compared with polysulfonamide fiber and Meta-aramid (NOMEX 1313) inherently heat-resistant fiber, flammability evaluation from LOI values and MCC data indicated that PI fiber exhibited lower flammability in terms of the ability to ignite and higher flammability in terms of the heat release capacity during combustion. This analysis for kinetics of the PI fiber is useful information for further study of numerical simulation of pyrolysis process of PI fabric when exposed to intense heat flux.