Investigation of readily processable thermoplastic-toughened thermosets. I. BMIs toughened via a reactive solvent approach

Document Type

Article

Publication Date

12-7-1998

Department

Department of Chemistry

Abstract

Moderate increases (∼ 50-75%) in the toughness of bismaleimides (BMIs) were achieved with very low-molecular-weight (∼ 1000 g/mol) imide thermoplastics at low levels of thermoplastic loading (∼ 10-20%). The thermoplastic was introduced into the BMI using a simple, one-pot, reactive solvent approach. In this approach, the reactive diluent of a two-part BMI was used as the reaction solvent for the thermoplastic synthesis. The BMI monomer was then dissolved in the thermoplastic reaction solution to yield a low-viscosity homogenous prepolymer. The viscosity of the thermoplastic solution was ∼ 6 Pa S at 55°C. The effect of thermoplastic loading and molecular weight on viscosity was determined by rheology, and the fracture toughness of neat resin plaques was determined by compact tension. Increasing the thermoplastic loading increased prepolymer viscosity without improving toughness, while increasing the thermoplastic molecular weight increased the toughness by only 25% more than the lowest-molecular-weight thermoplastic, yet increased viscosity fivefold. Fracture surfaces showed no obvious phase separation by scanning electron microscopy.

Publication Title

Journal of Applied Polymer Science

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