Expanded Graphite/Paraffin/Silicone Rubber as High Temperature Form-stabilized Phase Change Materials for Thermal Energy Storage and Thermal Interface Materials

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.

A hierarchically encapsulated phase-change film with multi-stage heat management properties and conformable self-interfacing contacts for enhanced interface heat dissipation

“…One of the most important reasons is that PCM films suffer from the leakage issue and low enthalpy capacity, and cause contamination problems. 36,41,42 Besides, PCM films include refined paraffins, polymers or copolymers, 43 which are characterized by low thermal conductivity between 0.17 and 0.35 W m −1 K –1 . 44 Furthermore, the requirements of no leakage of solid–liquid PCMs during phase transition and comfortable modulus ( E ) for intimate mechanical contact at working temperature are contradictory when conventional form-stable PCMs are applied as PhC-TIMs.…”

Multiwalled Expanded Graphite Coated with Nanometer-Thick Silica Layers for Thermal Management

“…An important point is that because most fillers are chemically inert, the interface interaction with the polymer matrix is weak, resulting in poor dispersion of the filler in the matrix, a tendency of accumulation, and higher interface thermal resistance. − In this case, optimization of the fillers’ thermal conductivity is not possible. Many strategies have been used to conduct surface modification of fillers. − The coating nanolayer on the filler surface is considered an effective surface modification method to improve the interfacial bonding force between the filler and the polymer matrix.…”

A mini review on paraffin‐graphene and related hybrid phase change materials for building energy applications

“…11,12 The high conductive fillers such as metal and metal oxide nanoparticles have been used as additives by various researchers in different PCMs such as Cu, 13 Al 2 O 3, 14 Ag, 15,16 ZnO, 17 and VO 2. 12 Similarly, the carbon-based nano-fillers 11,13 have been used to increase the conductivity of the PCMs including that of graphene, 23,24 graphene oxide (GO), 25,26 reduced GO, 27 carbon fibers, 28,29 carbon nanotubes, 30,31 graphite, expanded graphite, [32][33][34][35][36][37] biomass derived carbon, 38,39 etc. Ma et al 40 developed the PCMs based on paraffin, expanded graphite and nano-metal particles for the personal home cooling system.…”