A thermoplastic elastomer compound is disclosed having a high latent heat of fusion, indicative of a large thermal capacity. Use of thermal capacity agents, particularly linear paraffin waxes used in replacement of conventional plasticizer oils, contributes the thermal capacity advantages. Selection of the particular thermal capacity agent can provide an ability to engineer the amount of thermal capacity and the transition temperature in which that thermal capacity can be utilized as absorption or release of heat. The compound experiences a solid-solid phase transition whenever the thermal capacity agent melts into liquid form in the compound.