Polyethylene wax/EPDM blends as shape-stabilized phase change materials for thermal energy storage

Various amounts of a paraffinic wax were dispersed by melt mixing in an ethylene/propylene diene monomers (EPDM) rubber matrix. The resulting compounds were then vulcanized to obtain shape-stabilized rubbery phase change materials for thermal energy storage. The addition of the paraffinic wax induced a retardation in the vulcanization kinetics of the EPDM matrix. Calorimetric measurements evidenced how the homogenous distribution of the wax domains within the rubber, confirmed by electron microscopy observations, allowed for retaining the melting enthalpy of the neat paraffinic wax even at elevated concentration. The thermal energy storage and release capabilities of the investigated compounds were maintained even after various thermal cycles. The incorporation of polyethylene wax had a positive effect (increasing proportionally to its content) on the mechanical properties of the EPDM matrix, as documented from both the dynamical and the quasi-static tensile tests.