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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]

Thermally conductive and electrically insulating h-BN/MVQ and h-BN/SiCw/MVQ composites were prepared by internal mixing and two roll mixing, using 1-dimensional (1D) silicon carbide whiskers (SiCw) and 2-dimensional (2D) hexagonal boron nitride flakes (h-BN) as fillers, and methyl vinyl silicone rubber (MVQ) as polymer matrix. Surface modification of 1 D SiCw and 2 D h-BN was characterized by Fourier transform infrared spectroscopy (FT-IR) and contact angle analysis. Morphology, thermal conductivity and dielectric constant of h-BN/MVQ and h-BN/SiCw/MVQ were studied. The results indicated that surface modified h-BN and SiCw could be uniformly distributed in MVQ matrix. At the same volume filler loading, thermal conductivity of h-BN/SiCw/MVQ ternary composite was higher than that of h-BN/MVQ binary composite. When part of 2 D h-BN was instead of 1 D SiCw, there was synergistically enhanced effect between 1 D SiCw and 2 D h-BN for thermal conductivity. When volume ratio of h-BN/SiCw was 8/2, thermal conductivity of h-BN/SiCw/MVQ was higher than that of other ratio. Thermal conductivity of h-BN/SiCw/MVQ composite with different volume ratio was linearly fit with Agari' model. [ABSTRACT FROM AUTHOR]

A kind of shape-stable phase change materials (SSPCMs) was prepared by using graphene aerogel (GA) with different pore size adsorbing molten paraffin wax via vacuum impregnation. The characteristics of SSPCMs were determined by scanning electron microscopy (SEM), X-ray diffractometer (XRD), differential scanning calorimetry (DSC) and TCi thermal conductivity analyzer. The SSPCMs possessed a high comprehensive performance: a high thermal conductivity of 1.432 W/m·K (more than 400% increase over pure paraffin), a good capacity of thermal energy storage (more than 200 J/g), a ability to light-to-heat energy storage and coating effect (encapsulation ratio is about 55%) due to the three-dimensional GA foam structure with functions of thermal conductivity and adsorptive property. In addition, an energy conversion from light to heat was realized with the SSPCMs. For different morphologies of GA, as pore size of GA decreases, SSPCMs' thermal conductivity and solar energy usage efficiency increases and their leakage rate reduces. This means that pore size of GA can influence the properties of SSPCMs to some extent. [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]

Paraffin, due to its linear chain and saturated hydrocarbons with low thermal conductivity, is difficult to transfer energy effectively. Using amphiphilicity of graphene oxide (GO), Pickering emulsion of paraffin@GO was obtained and then paraffin@graphene microencapsulated phase change materials (MEPCMs) were achieved by chemical reduction through adding hydrazine hydrate. Thermally conductive PCMs with segregated structure were constructed by hot compression of paraffin@graphene microencapsules. Scanning electronic microscopy, differential scanning calorimetry and thermal conductivity test were used to characterize microstructure and thermal properties of MEPCMs. Meanwhile, the effect of graphene on the phase change latent heat and phase transition temperature was investigated. Results indicated that GO did not react with paraffin during the process of chemical reduction and the obtained MEPCMs were regular spheres. These MEPCMs had paraffin content of 99% or even more. Graphene working as shell materials increased the phase change latent heat of paraffin from 227.6 to 232.4 J/g, without affecting the phase transition temperature. The hot-compress molding makes graphene shell form segregated structure with more thermal pathways, further enhancing thermal conductivity. The segregated-structure PCMs with high latent heat and thermal conductivity can be applied in energy storage field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrathin Al-graphite (Al-Gr) composite foil is fabricated by hot-extrusion method. • High extrusion ratio is realized by the self-lubrication effect of graphite sheets. • High through-plane thermal conductivity (TPTC, 46 W/mK) is achieved for Al-Gr foil. • Enhanced TPTC is due to the clean interface and interconnection of graphite sheets. Heat dissipation film/ foil materials with high thermal conductivity in the through-plane direction are in high demand for improving the heat dissipation in the integrated circuits (IC) with high level of integration. In this letter, ultrathin aluminum-graphite (Al-Gr) composite foil with high through-plane thermal conductivity (46 W/m·K) was fabricated using the hot-extrusion technique. Specifically, the ultrathin Al-Gr composite foil was obtained through a high extrusion ratio (∼13:1) using the Al-Gr cylinder, during which the graphite sheets act as an effective self-lubrication media. The high through-plane thermal conductivity of the ultrathin Al-Gr composite foil is attributed to the coupled effects of the clean and tight interfacial bonding state between the Al and graphite sheets as well as the interconnected graphite sheets in the through-plane direction. Ultrathin Al-Gr composite foil with high through-plane thermal conductivity is expected as a competitive candidate for enhancing the heat dissipation capacity of the IC system. [ABSTRACT FROM AUTHOR]