Practical Technology of Toughening Epoxy Resin: Influence of Toughening Agents on Mechanical and Heat Properties

Abstract

This research studies the effect of several toughening agents, such as carboxyl-terminated polyether (CTPE), carboxyl-terminated polytetrahydrofuran (CTPF), carboxyl-terminated liquid nitrile rubber (CTBN), random-base liquid nitrile-butadiene rubber (RBNR) and core-shell polymer (CSP) containing polybutadiene, on epoxy resin. These epoxy resin systems containing various toughening agents showed different viscosity, in which the viscosity of CTPE and CTPF systems nearly unchanged and the viscosity of CTBN, RNBR and CSP systems increased significantly. The impact resistance of modified epoxy systems had been improved significantly, especially the CTPF system raised by 257.2%. Meanwhile, the heat resistance of epoxy systems containing different toughening agents showed different results. Compared with the pure sample, the hardness of all toughened systems decreased. CTPE and CTBN systems decreased significantly, while CTPF and CSP remained fundamentally unchanged. Toughness modification resulted in reduction of tensile strength and the retention ratio was CSP > RNBR > CTPF > CTBN > CTPE. Toughness modification resulted in reduction of compression strength and the retention ratio was RNBR > CSP > CTPF > CTBN > CTPE. All of the toughening systems kept the shear strength basically unchanged. The shear strength of the CSP system was even improved. In terms of peel strength, all of toughening systems had improved.