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 (D5 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.