Abstract

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.

Highlights

  • Epoxy resins, a member of the thermoset group, have widely used as matrix materials in the production of polymer matrix composite materials [1]

  • The ratios of components in Carboxy-terminated butadiene acrylonitrile (CTBN)/ epoxy blends cured by anhydride- and amine-based were given in Table 2 and Table 3, respectively

  • The CTBN modification effect on the tensile and fracture properties of CTBN/epoxy blends cured by anhydride- and amine-based agent was investigated, and the results obtained from the study were summarized below: 1. The curing temperature is a necessary procedure for obtaining the optimal toughening effect of rubber, in epoxies cured by anhydrite-based agent

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Summary

Introduction

A member of the thermoset group, have widely used as matrix materials in the production of polymer matrix composite materials [1]. Epoxy resins are preferred over other thermoset matrices in terms of their thermal stability, mechanical properties and processability [2]. They are commonly cured with amine-based agents to form rigid network polymers [3]. When epoxy resins are subjected to a curing process, they form a high cross-linking rate and turn into an amorphous thermoset material. The fracture behavior of final products produced by CTBN/ epoxy blends depends on the size of the rubber particles [12, 15,16,17]

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