Crystallization Behavior of Pebax-Graphene Composite Matrix with and without Supercritical Carbon Dioxide Assisted Polymer Processing Technique

The paper presents an in-depth analysis on the crystallization kinetics of Pebax-graphene composites when processed with and without supercritical fluid carbon dioxide (scCO₂) assisted extrusion at various graphene loading concentrations. Crystallization behavior was understood using the Avrami model for isothermal conditions and the Avrami, Ozawa, and combined Avrami-Ozawa model for non-isothermal conditions. The results from crystallization kinetics suggest that the crystal structure transformed from two-dimensional to three-dimensional when processed with scCO₂. The overall crystallization rate decreases when the composite matrix was processed with scCO₂ under both isothermal and non-isothermal conditions promoting possible exfoliation and crystal rearrangement resulting in homogenization of the composite matrix. The Arrhenius and Kissinger's activation energy was calculated, which is indicative of restriction opposed by graphene exfoliation to nucleation and crystal growth when processed with scCO₂. Crystallite size was calculated from the X-ray diffraction pattern using Scherrer's equation, where the crystallite size tends to decrease when processed with scCO₂ favoring the production of a homogeneous composite matrix due to crystal rearrangement and graphene exfoliation.