Morphology and Fracture Toughness of Thermoplastic Modified Epoxy Networks Prepared via Electromagnetic Processing

Epoxy resins have served as matrix resins for advanced composite structures because of their many desirable properties including outstanding adhesion, mechanical strength, dimensional stability, and high glass transition temperature. However, their appli­ cation is limited by the extensive curing cycles required to develop optimum mechanical properties. Recently, we have demonstrated that the rate of network formation for epoxy resins is significantly accelerated by utilizing electromagnetic radiation. Processing of this type has been shown to be effec­tive in curing epoxy resins quickly and efficienciently with the retention of good mechanical properties.

We have extended these studies to invesigate the effect of electromagnetic processing on the phase separation behavior of thermoplastic modified epoxy resins. , We have chosen amine terminated polysulfone oligomers as modifiers because of their high tough­ness, high modulus, high Tg and their stability against moisture. The mechanism of toughening in modified epoxy resins is thought to occur by the initiation and growth of shear yield deformations which are promoted by chemically incorporated phase separated ductile particles which act as stress concentrations upon loading.