Sponge-like form-stable phase change materials with embedded graphene oxide for enhancing the thermal storage efficiency and the temperature response in transport packaging applications

Hydrated salt-based form-stable phase change materials (FPCMs) with appropriate phase transition temperatures display great potentials in the thermal management of transport packaging. In this study, a series of novel hydrated salt-containing sponge-like FPCMs supported by superporous hydrogel (SPH) was fabricated through a foam polymerization method. N,O-carboxymethyl chitosan (CMCS) and graphene oxide (GO) were chosen as modifiers. The surfaces and inter structures of the FPCMs were examined by scanning electron microscopy (SEM) and optical microscopy (OM). Differential scanning calorimetry (DSC) was used to measure the thermal storage efficiencies of the FPCMs. The temperature responses and the temperature-regulation properties of the FPCMs were tested by a thermal conductivity measurement apparatus, a temperature recorder and an infrared thermography. The mechanical properties of the FPCMs were obtained by a texture analyser. DSC analysis demonstrates that the sponge-like FPCMs with teeming ionic groups can make them load and grasp more PCMs to acquire high energy storage efficiencies. The FPCM with GO&CMCS-modified SPH achieved the highest effective enthalpy percentage (87.8 %) and melting enthalpy (169.0 J/g), which was 43 % higher than that of nonsuperporous hydrogels (NSPH)-supported FPCM without CMC and GO. Meanwhile, the interconnected channels and the enhanced thermal conductivity of the GO-embedded FPCM with SPH led to a 42 % decrease in time to charge when compared with FPCM with NSPH. Besides, the hardness of FPCMs with SPH was remarkable enhanced by over 140 % comparing to FPCMs with NSPH since the internal pores of the SPH could absorb the impact energy. Moreover, the mechanical properties of the FPCMs were further improved when CMCS and GO were incorporated into the matrix. Additionally, thermal images show that the SPH-supported FPCMs, especially modified by CMCS and GO, exhibit a temperature-regulation property, which is beneficial in transport packaging for extending the time to discharge. As a result, the sponge-like FPCMs with embedded GO was an excellent candidate used for energy storage and thermal regulation in transportation.