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A simple graphene-carbon nanotube aerogel composite was prepared. In this paper, we studied the three-dimensional (3 D) thermally conductive frameworks with different ratios of graphene oxide (GO) and carbon nanotubes (CNTs). The effects of 3 D thermal conductive frameworks with different ratios of GO and CNT on the morphology, structure and thermal conductivity of phase change composites were also studied. The results show that the 3 D thermally conductive framework has the advantages of managing the thermal conductivity of phase change composites. The obtained phase change composite with only 1 wt% of graphene-carbon nanotube aerogels showed top-quality thermal conductivity of 0.76 W/m·K. The preparation process was simple and has the advantage of environmental protection, so which was suitable for practical applications using polyethylene glycol/graphene-carbon nanotube aerogel phase change composite as energy materials, and has manageable energy conversion, storage and thermal conductivity properties. [ABSTRACT FROM AUTHOR]

A novel kind of paraffin-based shape-stable phase change materials (SSPCMs) was prepared by introducing paraffin into reduced graphene oxide (rGO)/carbon nanotubes (CNTs) aerogel via vacuum-assisted impregnation method. The effects of ratio of rGO to CNTs in 3D network structure on morphology, structure and property of paraffin-based SSPCMs were investigated. The rGO/CNTs 3D network structure with high thermal conductivity, served as thermally conductive skeleton together. In particular, CNTs was used as a secondary heat conductive filler, which could be well dispered in the SSPCMs to conduct heat synergistically. The SSPCMs exhibited high thermal conductivity and excellent shape-stability. And the thermal conductivity of SSPCMs can be regulated by adjusting the ratio of rGO to CNTs in aerogels. These results indicate that 3D rGO/CNTs aerogels have advantages as thermally conductive skeleton, and can endow phase transition materials with stable shape, so as to realize the application of phase change materials in the field of heat dissipation. [ABSTRACT FROM AUTHOR]

A kind of paraffin@graphene/silicone rubber (SR) composite form-stable phase change material (PCM) was prepared in this paper. Paraffin@graphene phase change microcapsules were fabricated by electrostatic self-assembly method, then the microcapsules were added to the SR matrix to prepare paraffin@graphene/SR composites. The microstructure of the composite was characterized by scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) and thermal conductivity test results show that the phase change latent heat is 53.39 J g−1 and the thermal conductivity reaches 0.453 W m−1 K−1 for the composite with 30 phr paraffin@graphene microcapsules. The microcapsules enhance the thermal and mechanical properties of SR, which can be used for thermal energy storage. [ABSTRACT FROM AUTHOR]

Graphene encapsulating paraffin (paraffin@graphene) microcapsules were fabricated by electrostatic interaction-based self-assembly. An aqueous dispersion of graphene sheets charged with cation, were mixed with a water-based emulsion containning negatively charged paraffin droplet spheres to form self-assembled microcapsules. The morphology of the microcapsules was characterized by scanning electron microscope (SEM). Results show that the microcapsules with a well-defined spherical structure were prepared successfully. Differential scanning calorimeter (DSC) results indicate that the phase change latent heat are all above 200 J g−1. With a graphene mass fraction of 8 wt%, the thermal conductivity of the fabricated composites can reach 1.73 W m−1 K−1. Attributing to the interlocking of graphene with each other, the microcapsules enable lock the paraffin in the shell thus successfully avoiding its leakage during phase change process. The prepared phase change microcapsules are expected to apply in energy storage field. [ABSTRACT FROM AUTHOR]

Two kinds of carbon aerogels, graphene aerogels (GA) and carbon nanotubes-graphene aerogels (CGA), were prepared by modified hydrothermal method. The form-stable phase change materials (PCMs) were fabricated by adsorbing paraffin into carbon aerogels. Morphology, structure, form stability and thermal property were characterized by scanning electron microscope (SEM),in situX-ray diffraction (in situXRD) and differential scanning calorimeter (DSC). The results showed that GA presented wrinkled surface textures with curling edges, and carbon nanotubes (CNTs) were interspersed or attached to GA sheets. The phase transition temperature and the phase change enthalpy of the GA/paraffin PCM composite were 48.7 °C and 223.2 J/g, respectively. Thermal and mechanical properties of PCM composites achieved a qualitative leap with the adding of carbon aerogels. The PCM composites had a thermal conductivity of about 2.182 W/m K at the carbon aerogels loading fraction of 2 wt%. The form-stable PCM composites with high thermal conductivity and high enthalpy could be promising for thermal energy storage applications in construction field. [ABSTRACT FROM PUBLISHER]

The storage of latent heat using phase change materials (PCM) is an effective method of energy storage. In this study, silicone rubber (SR)/graphene nanoplates (GNPs)/paraffin@SiO2 phase change microcapsules (Pn@SiO2) shape-stabilized phase change materials (SSPCM) with high thermal conductivity, low leakage rate and tunable thermal management capability are prepared by method of add phase change microcapsules and thermal conductivity enhancer graphene nanoplates. The effects of Pn@SiO2 content on properties of the SR/GNPs/Pn@SiO2 (SGP) composites were investigated by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry. The results show that the enthalpy of phase change composites can be adjusted from 25.6 to 78.56 J·g−1 by changing the addition amount of Pn@SiO2 microcapsules. Moreover, the effect of GNPs on the thermal conductivity of SR matrix is greater than that of Pn@SiO2 on SR, as a consequence, the thermal conductivity of SGP composites decreases with the increase of Pn@SiO2. In addition, the thermal conductivity of SGP phase change composites can also reach 0.567 W·m−1K−1 after the addition of microcapsules, which dramatically shortens the response time of the material in the application. In summary, SGP composites have promising applications in the field of thermal storage. [ABSTRACT FROM AUTHOR]