Effect of the Extent of Cure on the Modulus, Glass Transition, Water Absorption, and Density of an Amine-Cured Epoxy
Abstract
The modulus, density, glass transition (Tg), and water absorption characteristics of an amine-cured resin (diglycidyl ether of bisphenol A (Epon 828)/ diaminodiphenyl sulfone (DDS) were studied as a function of extent of cure. The glass transition is a function of the extent of cure and reaches a maximum temperature, Tg, when it is completely cured; specimens with different extents of cure were formed by isothermal cure below Tg for different times. After slowly cooling, the density at each extent of cure was obtained at room temperature. Moisture absorption was monitored gravimetrically at 25 degrees C for two months at several humidity levels. The room temperature density and modulus decreased with increasing extent of conversion whereas the glass transition temperature and equilibrium water absorption increased. The equilibrium water absorption increased linearly with relative humidity, and the absorptivity increased linearly with specific volume. An interpretation of these anomalous results is made in terms of the nonequilibrium nature of the glassy state. The glass transition temperature increases as the extent of cure increases resulting in a material that is further from equilibrium at room temperature and therefore having more free volume and a greater propensity to absorb water.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1983
- Accession Number
- ADA127090
Entities
People
- John B. Enns
- John K. Gillham
Organizations
- Princeton University