Preparation And Properties Of SEBS Based Thermal Conductive Composite Phase Change Materials

Phase change materials can absorb or release a large amount of latent heat in the phase process,and the temperature is almost constant.The storage and release of heat energy through phase change latent heat is of great significance to improve the utilization efficiency of energy,alleviate the imbalance between energy supply and demand,and realize the accurate temperature control of electronic devices.However,there are two major problems in the large-scale commercialization of phase change materials:the liquid fluidity above the melting temperature and its low thermal conductivity.In this paper,paraffin wax（PA）is used as phase change material,which is encapsulated in thermoplastic elastomer SEBS,and the thermal conductivity is enhanced by adding thermal conductive filler,so as to obtain thermal conductive composite phase change material with excellent performance.The main contents and conclusions of this paper are as follows:（1）Using SEBS as the supporting material,SBES/PA form-stable phase change material was prepared by solution blending method to explore the maximum content of paraffin without leakage,and then expanded graphite was introduced to improve the thermal conductivity of phase change material.The shape stability test shows that the maximum content of paraffin in the shaped phase change material can reach 88.9 wt%.After the introduction of expanded graphite,the latent heat value of the composite phase change material will gradually decrease with the increase of its mass fraction.The analysis of thermal conductivity and electrical insulation showed that when 20 wt%expanded graphite was added,the thermal conductivity of sample EG-4 increased to1.175 W m^-1 K^-1,which was 6.42 times that of pure paraffin,but the volume resistivity decreased significantly.In addition,the addition of expanded graphite can also improve the thermal stability of composite phase change materials to a certain extent.（2）Hexagonal boron nitride was treated by solvent ultrasound and added to SEBS/PA form-stable phase change material as thermal conductive filler.SEM and XRD tests showed that solvent ultrasonic treatment did not destroy the structure of hexagonal boron nitride,and it had good compatibility with SEBS and paraffin,and there was no chemical reaction after blending.The experimental results show that when the boron nitride content is 20 wt%,the thermal conductivity of the composite phase change material is 0.986 W m^-1 K^-1,the electrical insulation performance is also improved,and the order of magnitude of volume resistivity is maintained at 10¹⁶Ωcm.（3）Silver-coated hollow glass microspheres（Ag@HGMs）were prepared by a green chemical silver-plating method,and then mixed with hexagonal boron nitride as a hybrid thermal conductive filler for SEBS/PA form-stable phase change materials to prepare SEBS/PA/BN/Ag@HGMs composite phase change materials.The surface of spherical Ag@HGMs is covered by flakes of hexagonal boron nitride,which are uniformly distributed inside the sample.Thermal conductivity tests show that Ag@HGMs and hexagonal boron nitride have a synergistic effect on improving the thermal conductivity of the composites.When the content of the mixed filler is 20 wt%,the thermal conductivity of BN/Ag@HGMs-4 is as high as 1.54 W m^-1 K^-1,and the volume resistivity at this time is 3.12×10¹⁵Ωcm.