The Source of Variability in the Burning Behavior of Poly(Aryl-Ether-Ether-Ketone) (PEEK) in a Cone Calorimeter

摘要

The fire performance of a semi-crystalline thermoplastic, poly(aryl-ether-ether-ketone) (PEEK) was investigated using a cone calorimeter, thermal analysis and numerical modeling in an effort to explain the observed variability in fire test results with this polymer. The heat release rate, total heat release, mass loss, effective heat of combustion, and the ignition times at various heat flux settings and sample thicknesses were measured for PEEK samples that were conditioned to three levels of moisture: 0% (dry), 0.35% (ambient) and 0.73% (wet). The fire response changed drastically over this small range of moisture. For wet samples, both the ignition time and the peak heat release rate were lower, and visual inspection of the samples during the cone calorimeter tests indicated small bubbles forming on the surface of the specimen at the melting temperature of PEEK prior to ignition. For dry samples, a glossy smooth surface was formed and surface bubbles were absent prior to ignition. Numerical modeling of PEEK burning behavior, treating bubble formation as a physical process that reduced the thermal conductivity of the surface and the in-depth absorption of radiation, was able to account for the effect of moisture on fire test results.