The Research Of High Impact Epoxy Potting Material

Epoxy resin(EP) is a kind of important thermosetting resin, which is characterized with outstanding performance such as adhesive and mechanical properties, abrasion and chemical resistance, low costs. And extensively used in adhesive, construction, aerospace, electrical and military applications. Particularly in encapsulation. But the brittleness, poor impact and fatigue resistance of cured resin makes it hard to meet the needs of engineering applications. So toughening of the resin is essential. The main objective of this study is to improve the toughness of a certain type of encapsulants.The toughening of epoxy resin has been extensively studied by many researchers. Many approaches have been developed to improve the toughness of brittle matrix, which includes the addition of liquid rubber, thermoplastic, nanoparticle and hyperbranched polymer. The addition of liquid rubber is the most early approach favoured by researchers. The liquid carboxyl terminated butadiene arylonitrile copolymer(CTBN) is the chief concern.In this study the epoxy resin used was diglycidyl ether of bisphenyl A, with an average molecular weight of 2500. The CTBN, which presents different level of nitrile(-CN) value was employed. CTBN-10(contains 10% of CN) and CTBN-25(contains 25% of CN) present an average molecular weight of 2500. CTBN-17.5(contains 17.5% of CN)presents an average molecular weight of 3500. Polyether amine D-230 as cure agent. Ethylene glycol diglycidyl ether as diluent. Silicone oil as defoamer. Different kind of rubber with different amount was added, physical blend and chemical bonding have been used to prepare the encapsulant. Impact strength, tensile strength, elongation at break, thermogravimetric analysis(TGA), dynamic mechanical analysis(DMA), heat conductivity coefficient have been studied.The results from infrared spectroscopy displayed the formation of ester group between EP and CTBN. The impact strength and elongation at break at first increase and then decrease with the addition of CTBN. Tensile strength, storage modulus, mechanical loss, glass transition temperature decrease with the addition of rubber. But the addition of rubber has little effect on heat conductivity coefficient. Chemical bonding is better than physical blend. The CTBN, which has lower CN value has better toughening effect in the same molecular weight.