Thermal and dielectric properties of the epoxy resin toughened by different kinds of liquid rubbers

摘要

Epoxy resin is widely used in the electrical equipment, such as dry-type bushing and transformer, and epoxy resin is friable material which needs to be toughened. Adding liquid rubbers is one of the most mature and effective ways to toughen matrix. Four kinds of liquid rubbers (HTPB, CTBN, HTBN and EHTPB) are adopted to toughen epoxy resin respectively, and then the thermal and electrical properties are measured and compared. Phase separation occurs between all these four liquid rubbers and epoxy resin during epoxy resin curing, and the dispersed rubber particles play an important role in toughening. For HTBN and CTBN, the dispersion phase is more evenly. All kinds of liquid rubbers are resulted in a slight decrease in the glass transition temperature, and have little effect on the thermal conductivity and diffusion coefficient of epoxy resin matrix. DC resistivity has a different extent of decline after the addition of liquid rubbers. In dielectric spectroscopy, all the kinds appear a relaxation behavior which should be caused by the interfacial polarization between rubber particles and epoxy resin. The time and strength of these relaxations are related to the kind of liquid rubber. When using the liquid rubber to toughen epoxy resin, the kind and content of liquid rubbers should be considered based on the product requirements.