Changes in activation energy and kinetic mechanism during EVA crosslinking

Abstract The activation energy and kinetic mechanism throughout the crosslinking process of copolymer ethylene-vinyl acetate (EVA), initiated by dicumyl peroxide (DCP), were determined in the framework of a multi-step solid-state process. Crosslinking was performed in a differential scanning calorimeter (DSC) under non-isothermal conditions. The activation energy (E) was determined by means of the isoconversional integral method using the Cai approach. The E values (87–105 kJ mol −1 ) were found to be dependent on the crosslinking conversion ( α ) and DCP content. Kinetic mechanisms were determined by the Criado method from Eα ( T ) data through the use of the master plots of theoretical kinetic models. At 0.1  α F n mechanisms). At α  ≥ 0.5, the medium becomes heterogeneous and EVA crosslinking occurs through a diffusion-controlled reaction ( D n mechanisms). At α  ≅ 0.9, the temperature increases and the EVA crosslinking follows homogeneous kinetics with F n mechanisms.