Cure and Properties of Thermosetting Polymers.

Thermosetting materials e.g., epoxies and polyimides are used in composites, coatings and adhesives. Unlike their thermoplastic counterparts, molecular structure macroscopic property relationships in thermosets are not well developed hence the current research. A general model for thermosetting materials which relates polymerization to properties is being developed. In this, a time temperature transformation TTT cure diagram relates the principal states of matter encountered i.e., liquid, rubber solgel and gel, and glass sol, solgel and gel to gelation and vitrification phenomena. The model is extended to rubber-modified thermosetting systems to show that a given chemical formulation can provide different morphologies and hence different material behavior. It is also extended to high temperature polymers where polymerization and degradation reactions compete. Computed and experimental TTT diagrams are compared.