Bisphenol-A benzoxazine and cycloaliphatic epoxy copolymer for composite processing by resin infusion

Abstract

The process and high-temperature performance of bisphenol-A based benzoxazine were tailored by copolymerizing with bi-functional cycloaliphatic epoxy resin in order to be used as a matrix for the advanced composite fabrication. The melt viscosity, cure kinetics, thermo-mechanical, and tensile properties of the systems with various cycloaliphatic epoxy resin and benzoxazine concentrations were studied using rheometer, differential scanning calorimetry, dynamic mechanical analyzer, and micro-tensile tester, respectively. Mixtures with cycloaliphatic epoxy resin concentration greater than 25 wt.% provided a suitable viscosity for composite processing by resin infusion. The isothermal and nonisothermal cure kinetics of the benzoxazine and cycloaliphatic epoxy resin reaction was studied. The predicted kinetic curves based on Kamal and Sourour phenomenological reaction model expanded with a diffusion factor resulted in an agreement with the experimental kinetic curves. The investigation of copolymers with various mixture compositions showed an increase of 56% in glass-transition temperature ([Formula: see text] and 79% in cross-linking density by increasing epoxy concentration up to 40 wt.% in comparison with homopolymerized benzoxazine.