Advances in Liquid Crystalline Epoxy Resins for High Thermal Conductivity.

Younggi Hong,Munju Goh

doi:10.3390/polym13081302

Abstract

Epoxy resin (EP) is one of the most famous thermoset materials. In general, because EP has a three-dimensional random network, it possesses thermal properties similar to those of a typical heat insulator. Recently, there has been substantial interest in controlling the network structure of EP to create new functionalities. Indeed, the modified EP, represented as liquid crystalline epoxy (LCE), is considered promising for producing novel functionalities, which cannot be obtained from conventional EPs, by replacing the random network structure with an oriented one. In this paper, we review the current progress in the field of LCEs and their application to highly thermally conductive composite materials.

Highlights

Epoxy resin (EP) based thermosetting polymers are used in various industries because of their excellent adhesion, thermal resistance, chemical resistance, and mechanical strength owing to formation of a three-dimensional network structure with curing agents such as acid-free amine phenol [1,2,3,4]
We provide an overview of studies aimed at improving the thermal conductivity of EP by introducing liquid crystallinity into the molecular structure in order to complement the many studies that have attempted to ascertain the thermal properties of EP arising from the three-dimensional network structure
Prior studies have shown that the use of liquid crystalline epoxy (LCE) results in higher thermal conductivity than that obtained when using typical EPs, and when a complex is manufactured by adding a high-thermal-conductivity filler, the overall thermal conductivity becomes higher than that of the cured epoxy in the diglycidyl ether of bisphenol A (DGEBA) system

Summary

Introduction

Epoxy resin (EP) based thermosetting polymers are used in various industries because of their excellent adhesion, thermal resistance, chemical resistance, and mechanical strength owing to formation of a three-dimensional network structure with curing agents such as acid-free amine phenol [1,2,3,4]. Heat transfer of cured EP is facilitated by the transfer of phonon oscillations in the crystalline and non-crystalline regions It is expressed by the Debye equation. To achieve high thermal conductivity, the variable l needs to be increased This makes it necessary to minimize static scattering in the crystalline region of phonons and dynamic scattering related to orientation. To this end, we can improve the thermal conductivity of polymers by enhancing the crystallinity of polymeric materials. LCE has a molecular structure that can reduce phonon scattering and increase crystallinity in microscopic regions due to the domain structure formed by the self-assembly of liquid crystal molecules. It is possible to improve the thermal conductivity, and rod-shaped LCE exhibits a thermal conductivity higher than 0.4 W/mK, which is twice as large as the thermal conductivity observed for diglycidyl ether of bisphenol A EP [18]

Molecular Design of Liquid Crystalline Epoxies

Liquid Crystalline Epoxies Bearing Diglycidyl Moieties at the Side Positions

Orientation Effect on Thermal Conductivity of Liquid Crystalline Epoxies

Findings

Conclusions