High-efficiency improvement of thermal conductivities for epoxy composites from synthesized liquid crystal epoxy followed by doping BN fillers. (15th March 2020)

• Record Type: Journal Article
• Authors: Yang, Xutong; Zhu, Jiahua; Yang, Dong; Zhang, Junliang; Guo, Yongqiang; Zhong, Xiao; Kong, Jie; Gu, Junwei
• Is Part Of: Composites. Number 185(2020)
• Publication Date: 2020-03-15
• Subjects: Liquid crystal epoxy (LCE) -- Intrinsic -- Boron nitride -- Thermally conductive composites; Composite materials -- Periodicals; Materials science -- Periodicals; Composite materials; Periodicals; Electronic journals; 620.118
• DOI: 10.1016/j.compositesb.2020.107784
• Languages: English
• ISSNs: 1359-8368

Abstract

Abstract: Liquid crystal epoxy resin presents high intrinsic thermal conductivity coefficient ( λ ). However, the complex molecular structure design and tedious synthesis process severely limit its rapid development and further industrial application. In this work, a kind of liquid crystal epoxy (LCE) based on biphenyl mesomorphic unit is synthesized from 4, 4′-biphenol, triethylene glycol, and epichlorohydrin. Curing agent of 4, 4′-diaminodiphenyl methane (DDM) and boron nitride (BN) fillers are both performed to prepare the intrinsic highly thermally conductive liquid crystal epoxy resin (LCER) and BN/LCER thermally conductive composites via casting method. LCE has been successfully synthesized with expected structure, presenting nematic liquid crystal with range of 135–165 °C. LCER shows liquid crystal property with intrinsic λ up to 0.51 W/mK, about 3 times higher than that of general bisphenol A epoxy resin (E−51, 0.19 W/mK). Simultaneously, LCER has good thermal stability with heat resistance index ( T HRI ) being 183.9 °C. In addition, the λ values of the BN/LCER thermally conductive composites increase with the increasing loading of BN fillers. When the content of BN fillers is 30 wt%, the λ value of BN/LCER thermally conductive composites is 1.02 W/mK, twice as much as that of pure LCER, also much higher than that of 30 wt% BN/E−51 composites (0.52 W/mK).