Mechanical, Thermal, and Electrical Properties of BN–Epoxy Composites Modified with Carboxyl-Terminated Butadiene Nitrile Liquid Rubber

Abstract

Filled high thermal conductivity epoxy composite solves the problem of the low thermal conductivity of the epoxy resin itself, but the addition of the thermal conductive filler reduces the mechanical properties of the composite, which limits its application in the field of high voltage insulation. In this work, carboxyl-terminated butadiene nitrile liquid rubber (CTBN) was used to toughen the boron nitride-epoxy hybrid system, and the effects of different contents of CTBN on the mechanical properties, thermal conductivity, glass transition temperature, thermal stability, and dielectric properties of the composites were investigated. The results showed that when the content of CTBN was 5–15 wt.%, the CTBN formed a dispersed island structure in the epoxy resin matrix. The toughness of the composite increased by about 32%, the breakdown strength was improved, and the thermal conductivity was about 160% higher than that of pure epoxy resin. As the CTBN content increased, the glass transition temperature and thermal stability of the composite decreased and the dielectric constant and the dielectric loss increased. When the CTBN content is 10–15 wt.%, a toughened epoxy composite material with better comprehensive properties is obtained.

Dielectric Relaxation Characteristics of Epoxy Resin Modified with Hydroxyl-Terminated Nitrile Rubber

“…Liquid rubber, such as hydroxyl-terminated liquid nitrile rubber (HTBN), is one kind of efficient toughener for epoxy resin owing to the simple operation process [ 1 , 2 ]. Epoxy resin/liquid rubber composites and their nano modified composites have been applied to electrical packaging and power equipment, so the dielectric properties must be of comparable concern [ 3 , 4 ]. Liquid rubber uniformly disperses in the matrix in the form of discrete phases, and the dielectric properties are changed, which is attributed to the variation of relaxation behaviours [ 5 , 6 ].…”

Improved thermal and electrical properties of epoxy resin composites by dopamine and silane coupling agent modified hexagonal BN

“…At the same time, the insulation material in the equipments work for a long time and the insulation performance could be weakened. [1,2,3] As a result, more attention has been paid to thermal management, which becomes a key issue in many fields. Therefore, the research into the preparation and performance of materials for electrical insulation with high thermal management capabilities is important.…”

“…Consequently, many properties of the composite have a severe decline, including processing (such as a significant increase in viscosity), mechanical properties (a decrease in toughness, mechanical strength, and flexibility, for example), and electrical properties (a significant decrease in dielectric strength or an increase in dielectric constant), and so on. [2,[20][21]22] Many scientific studies have been conducted in China and other countries to improve the thermal conductivity and electrical properties of polymer composites. For instance, fillers with different shapes and sizes are used to form an efficient thermal conductive network or to optimize the development of internal conductive networks.…”

Effect of Toughening with Different Liquid Rubber on Dielectric Relaxation Properties of Epoxy Resin

“…Despite a vast literature concerned on the mechanical properties of the toughened epoxy resins, a growing attention has been drawn to its dielectric properties in recent years [11][12][13][14][15][16][17]. Better 2 of 13 properties in toughness, thermal conductivity, and breakdown strength were achieved from a ternary copolymer, consisting of epoxy matrix, micron hexagonal boron nitride(h-BN), and CTBN [17]. In addition, much attention has been paid to the blending rubber, such as triblock copolymer poly(styrene)-block-poly(butadiene)-blockpoly(methylmethacrylate) (SBM), for better performance in mechanical and thermal [18].…”