Kinetic and Thermodynamic Investigation by High-Pressure Calorimetry

Low-density polyethylene (LDPE) is produced by high-pressure radical polymerisation which requires the formation of radicals which react with monomers to start a polymer chain. Peroxides are widely applied initiator splitting their oxygen-oxygen bond under specific temperatures homolytically. Investigating the kinetic of this decomposition reaction under process conditions is crucial to predict and optimise the polymerisation on an industrial scale. Due to the harsh process conditions, the analytical options to examine the kinetic of peroxide decomposition are limited. So far, spectroscopy of the decomposition products was applied by Luft and Buback. In this work, high-pressure calorimetry is introduced as new method for these kinetic investigations. The evaluation is optimized and validated and influence factors identified. Especially, the effect of solvent and pressure on different peroxides as well as the presence of another peroxide is analyzed.