Calorimetric and dynamic mechanical behavior of phase change materials based on paraffin wax supported by expanded graphite

Abstract

This study addressed the characterization and description of calorimetric and dynamic mechanical properties of phase change materials (PCMs) based on linear low-density polyethylene (LLDPE), paraffin wax (W) and expanded graphite (EG). The mentioned properties were evaluated over the temperature range from 0°C to 60°C, which is the expected range for practical applications of these materials. The appropriate dispersion of EG particles within the LLDPE/W blends was confirmed using XRD measurements. Moreover, the partial intercalation of the W between the graphite layers was confirmed. The broad investigation of the dynamic mechanical properties at various temperatures and frequencies provides complex information concerning the mechanical behavior of LLDPE/W blends as well as LLDPE/W/EG composites. The results showed that incorporation of EG into LLDPE/W blends led to a significant increase in their dynamic mechanical properties, which was proportional to the EG content.Moreover, it was shown that the melting and crystallization characteristics of the investigated materials did not change upon cycling (30 heating/cooling cycles), and their dynamic mechanical properties stayed constant over five thermal cycles.