Anisotropic Enhancement in Thermal Conductivity of Graphene Foam/Polymer Composites Based on Uniaxial Compression

• Published in: Macromolecular materials and engineering Vol. 307; no. 12
• Main Authors: Gao, Ge, Sun, Mingqi, Dai, Bing, Yang, Lei, Liu, Kang, Yang, Zhenhuai, Han, Jiecai, Zhu, Jiaqi
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.12.2022
• Subjects: anisotropy; Compressive properties; controllable thermal properties; Graphene; graphene foams; Heat conductivity; Heat transfer; microstructures; Polymer matrix composites; polymeric matrix composites; Thermal conductivity; Unit cell
• ISSN: 1438-7492; 1439-2054
• DOI: 10.1002/mame.202200373

High‐performance thermal interface materials are in increasing demand because of the problems of dissipating heat from high‐power computing devices. To solve this problem, this study proposes a method of microstructural design through uniaxial compression of graphene foam along the out‐of‐plane direction. The thermal conductivity of the composites with graphene foam shows an anisotropic growth along the direction of the compressive strain. The in‐plane thermal conductivity increases significantly from 0.189 to 1.669 W m−1 K−1 at an extremely low filler content of 2.24 vol%, whereas the out‐of‐plane thermal conductivity increases slightly to 0.303 W m−1 K−1. Moreover, the samples exhibit outstanding in‐plane thermal conductivity enhanced efficiency, which reaches 415.19% at a 1.29 vol% graphene content. The mechanism of anisotropic thermal conductivity enhancement is revealed by constructing a theoretical model based on a geometrical unit cell simplified from the morphology of graphene foam. This uniaxial compression method of a 3 structure provides a novel direction for improving the thermal conductivity of polymeric matrix composites more controllably. Graphene foam/epoxy composite with an in‐plane thermal conductivity of 1.669 W m−1 K−1 is fabricated using graphene foam that is densified by uniaxial isostatic compression. The composites exhibit an in‐plane thermal conductivity enhances efficiency of up to 452.2%. Through constructing a single‐cell model of graphene, the equivalent thermal conductivity of composites and the mechanism of this anisotropy are studied.