A novel fluid-filler/polymer composite as high-temperature thermally conductive and electrically insulating material

Significance 

The current trend of electronic device miniaturization demands improvements in the thermal conductivity and electrical insulating capacity of materials used for production. With the objective of identifying an effective heat conductor, researchers have sought after polymers due to their attractive attributes such as low cost, light weight and good processability among others. Unfortunately, most polymers are poor thermal conductors and generally cannot reach the dissipation requirements of the electronic device industry. Alternatively, addition of fillers of high thermal conductivities to the polymer matrices helps obtain polymer composites of high thermal conductivity and yet retain their inherent desirable properties. However, composites with appropriate thermal conductivities are mostly achieved with high filler loading, sacrificing the light weights, low costs, and excellent processabilities of the polymeric materials. The work presented herein therefore seeks to address this issue by providing a new approach for the development of thermally conductive and electrically insulating materials by incorporating fluid heat convection into polymer material.

Researchers led by Professor Chuanxi Xiong at Wuhan University of Technology in China proposed a study to incorporate liquid paraffin microcapsules into epoxy resin to prepare fluid-filler/polymer composite materials. Their main objective was to introduce fluid heat convection into thermally conductive and electrically insulting materials to match the desired attributes. Their research work is now published in journal, Composites Science and Technology.

The researchers initiated their experimental procedure by synthesizing liquid paraffin microcapsules which they then added to epoxy resins to prepare the liquid paraffin microcapsules/ epoxy-resin composites. The team then characterized the micro morphologies of the paraffin microcapsules while still analyzing their chemical structures. The thermal and electrical conductivities with various liquid paraffin microcapsules contents were measured, and the heat release efficiencies of the composite with 25 vol% liquid paraffin microcapsules content at different temperatures were obtained as well. Eventually, the effects of the liquid paraffin microcapsules on the tensile and bending strengths and tensile strain to failure were investigated.

The research team observed that the liquid paraffin microcapsules formed neat structures after being acidized for several minutes using polyvinyl alcohol as the emulsifier. The heat dissipation efficiency remarkably improved above certain temperatures with 25 vol% liquid paraffin microcapsules, although there was no significant thermal conductivity enhancement at room temperature. They also noted that the liquid paraffin microcapsules/epoxy composites containing 20 vol% of liquid paraffin microcapsules filler exhibited tensile strengths, bending strengths, and breaking elongations that were 14.3%, 12.5%, and 30.5% higher, respectively, than those of the pure epoxy resin.

The Chuanxi Xiong and co-workers study has introduced fluid heat convection into thermally conductive and electrically insulating material by preparing liquid paraffin microcapsules/epoxy-resin composites. Their work has shown that the fluid heat convection efficiency increases with increasing temperature. Moreover, electrical conductivity and dielectric measurements have demonstrated that the liquid paraffin microcapsules/epoxy-resin composites are good electrical insulators. These results point out that fluid-filler/polymer composites could be promising as heat conduction materials that are effective at relatively high temperatures.

A novel fluid-fillerpolymer composite as high-temperature thermally conductive and electrically insulating material. Advances in Engineering

About the author

Dr. Chuanxi Xiong received his Ph.D in Composite Materials from Wuhan University of Technology(WHUT). He is now the professor of School of Materials Science and Engineering of Wuhan University of Technology. He has long been engaged in functional polymer composite materials and energy storage materials based on polymers. He is the corresponding author of this paper.

About the author

Quanling Yang is the co-corresponding author of this paper. He received his Bachelor Degree in Applied Chemistry and Master Degree in Polymer Chemistry and Physics from Wuhan University under the supervision of Prof. Lina Zhang in 2008 and 2010, respectively. After three years of doctoral course in Biomaterials Science of The University of Tokyo under the supervision of Prof. Akira Isogai, he received his Ph.D. degree in Sep. 2013. Whilst a graduate student he received a Research Fellowship for Young Scientists from the Japan Society for the Promotion of Science (JSPS) in 2012. From Oct. 2013 to Sep. 2015, he worked as JSPS Postdoctoral Research Fellow in The University of Tokyo. Then he joins Wuhan University of Technology and works as a Professor in School of Materials Science and Engineering.

His main research interests focus on construction of environment-friendly materials based on biomass, functional polymer composite materials, 1D and 2D nanomaterials, and energy storage materials.

About the author

Zhaodongfang Gao

Received his B.S degree in Materials Science and Engineering from Wuhan University of Technology in 2012. He is currently a doctoral candidate in School of Materials Science and Engineering of Wuhan University of Technology under the supervision of Prof. Chuanxi Xiong.

About the author

Qi Zhao

Received his M.S degree in Materials Science and Engineering from Wuhan University of Technology under the supervision of Prof. Chuanxi Xiong in 2016. He has expertise in the field of thermal insulation materials. He is currently working as research associate in the State Grid Corporation of China.

About the author

Chuanbin Li, born in Shandong province. He has received his Bachelor Degree in material and engineering from University of Jinan in 2015. He is studying in Wuhan University of technology now, major in advanced polymer materials under the supervision of Prof. Chuanxi Xiong in School of Materials Science and Engineering. His main research interests focus on polymer processing, thermally conductive and electrically insulating materials, and electrocaloric materials.

Reference

Zhaodongfang Gao, Qi Zhao, Chuanbin Li, Shan Wang, Lijie Dong, Guo-Hua Hu, Quanling Yang, Chuanxi Xiong. A novel fluid-filler/polymer composite as high-temperature thermally conductive and electrically insulating material. Composites Science and Technology volume 150 (2017) pages 128-134

 

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