Composite phase change materials of ultra-high molecular weight polyethylene/paraffin wax/carbon nanotubes with high performance and excellent shape stability for energy storage

Abstract Ultra-high molecular weight polyethylene (UHMWPE)/carbon nanotubes (CNT) porous skeleton was prepared by microwave sintering, then paraffin wax (PW) was absorbed into UHMWPE/CNT porous skeleton by vacuum, obtaining composite phase change materials (CPCM). Differential scanning calorimetry (DSC) results showed that with CNT content of 1.5%, the PW adsorption of CPCM reached 59.91% and latent heat of the CPCM hardly changed after 20 melting/freezing cycles. Furthermore, thermal conductivity of porous matrix and CPCM from 0.1858 and 0.3012 W m − 1 K − 1 to 0.3272 and 0.4225 W m − 1 K − 1 with the CNT content increased (from 0% to 2%), respectively. In addition, the CPCM had a great shape stability. When the temperature reached 70 °C, PW in CPCM hardly leaked. In the photothermal conversion, CPCM realized the function of energy storage and release. Therefore, the CPCM prepared by a facile and environmentally friendly strategy with high energy storage efficiency, outstanding thermal repeatability, excellent thermal stability and high thermal conductivity had a broad prospect in the application of energy storage.