Characterization of Mechanical of CTBN Liquid Rubber‐Modified Epoxy Cured by Anhydride- and Amine-Based Agent

The main purpose of this work is to reveal the effects of carboxyl-terminated butadiene–acrylonitrile (CTBN) rubber particles on the fracture and tensile behavior of anhydride-and amine-cured epoxy/CTBN blends. In this study, 1 wt.%, 3 wt.%, 5 wt.%, 7 wt.%, 10 wt.% and 15 wt.% CTBN were added to two different epoxy-hardener systems. The CTBN/epoxy blends were prepared by ultrasonic mixing device and curing processes were determined by DSC analysis. As CTBN fraction by weight increased in both epoxy systems, a decrease in tensile strength and modulus was detected, but deformation ability improved. The fracture toughness of CTBN/epoxy blends cured with amine-based hardener increased up to 10 wt.% CTBN addition and then decreased. The average rubber particle size was found to have a significant effect on the fracture toughness of CTBN/epoxy blends. Compared to pure epoxy, fracture toughness increased approximately 3.5-fold in amine-cured 10% CTBN / epoxy blend. In CTBN/epoxy blends cured by amine-based curing agent, CTBN shifted the reaction rate and thus it was provided better control over CTBN particle size in the cured CTBN/epoxy. The toughening mechanisms induced by CTBN, such as rubber cavitation and matrix shear banding, contributed to the enhanced fracture toughness of the amine-cured CTBN/epoxy.