Title

Application of 2-oxazoline/bismaleimide resins to high-performance composites

Date of Completion

January 1994

Keywords

Chemistry, Polymer|Engineering, Aerospace|Plastics Technology

Degree

Ph.D.

Abstract

Novel oxazolines were used as comonomers to improve the toughness and processability of bismaleimide resins. Specifically, thermosetting resins utilizing short-chain and extended bisoxazoline and bismaleimide monomers were studied for use as matrices for carbon fiber reinforced composites. Thermo-mechanical properties and fracture toughness of both neat resins and uniaxial carbon-fiber reinforced composites were evaluated. The oxazoline-modified systems had several advantages, including a large latent reaction region of up to 40$\sp\circ$C between peak melting and onset of polymerization, easy hot-melt impregnation of carbon fiber tows, and lower volume shrinkage upon curing. Composites using the extended resins had composite $G\sb{Ic}$ values of up to 670 J/m$\sp2,$ comparable to that of commercial resins. Addition of up to 17 w/w% carboxyl-terminated butadiene-acrylonitrile liquid rubber to the oxazoline-based resins increased the neat resin fracture toughness, with a corresponding increase in composite fracture toughness of up to 16%. The effect of addition of the rubber on the curing of the zwitterionic resins and their morphology was also investigated. ^