Abstract
In this work, expanded graphite/paraffin/silicone rubber composite phase-change materials (PCMs) were prepared by blending the expanded graphite (EG), paraffin wax (PW) and silicone rubber (SR) matrix. It has been shown that PW fully penetrates into the three dimensional (3D) pores of EG to form the EG/PW particles, which are sealed by SR and evenly embedded in the SR matrix. As a result of the excellent thermal stability of SR and the capillary force from the 3D pores of EG, the EG/PW/SR PCMs are found to have good shape stability and high reliability. After being baked in an oven at 150 °C for 24 h, the shape of the EG/PW/SR PCMs is virtually unchanged, and their weight loss and latent heat drop are only 7.91 wt % and 11.3 J/g, respectively. The latent heat of the EG/PW/SR composites can reach up to 43.6 and 41.8 J/g for the melting and crystallizing processes, respectively. The super cooling of PW decreased from 4.2 to 2.4 due to the heterogeneous nucleation on the large surface of EG and the sealing effect of the SR. Meanwhile, the thermal conductivity of the EG/PW/SR PCMs reaches 0.56 W·m−1·K−1, which is about 2.8 times and 3.73 times of pure PW and pristine SR, respectively. The novel EG/PW/SR PCMs with superior shape and thermal stabilities will have a potential application in heat energy storage and thermal interface materials (TIM) for electronic devices.
Highlights
The environmental pollution issues and the exhausting resources of petrochemical fuels have accelerated the development of clean and sustainable energy as well as energy storage technologies.One of them is the thermal energy storage technology
This phenomenon is probably due to the increased content of expanded graphite (EG)/paraffin wax (PW) that gradually deteriorates the mechanical properties of the composite materials
High temperature form-stable EG/PW/silicone rubber (SR) composite phase-change materials (PCMs) were prepared by blending EG, PW and SR together
Summary
The environmental pollution issues and the exhausting resources of petrochemical fuels have accelerated the development of clean and sustainable energy as well as energy storage technologies. Desirable PCMs should have large thermal storage capacity and high thermal conductivity The latter ensures that heat, to be absorbed or released, can be quickly transferred within the PCMs. Among many types of PCMs, PW is the most preferred one because of its high energy density, nontoxicity and low vapor pressures. The published research generally requires the use of microencapsules of PW to avoid the leakage issue [39,40,41] This considerably complicates the fabrication process of SR based PCMs. instead of using the complex microencapsulation procedure and expensive material as graphene, we intend to use more cheaper material EG to capture PW and simultaneously enhance the high thermal conductivity of SR based PCMs. A new PCM composite with large thermal storage capacity and high thermal conductivity was fabricated using PW, EG and SR as the raw materials.
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