Nonisothermal Degradation Kinetics of Ultra-High Molecular Weight Polyethene Composites Filled with Carbon or Aramid Fibers

The thermal degradation in static air of three types of composite materials based on ultra-high molecular weight polyethene with unmodified and modified carbon fibers or aramid fibers have been investigated under nonisothermal conditions at a heating rate of 10 K min(-1). The Coats-Redfern method was used to determine the kinetic parameters. The analysis of the result obtained by the Coats-Redfern method shows that the thermal degradation process of these composites corresponds to a diffusion-controlled reaction (D(5) mechanism, three-dimensional diffusion described by Zhuravlev-Lesokhin-Tempelman equation). It was found that the composites with unmodified and modified carbon fibers or aramid fibers possess the highest thermal stability at 3 mass % fiber content. The activation energy, frequency factor and the changes of entropy, enthalpy and Gibbs energy for the active complex of the composites were also measured.