Dielectric Analysis of the Cure of Thermosetting Epoxy/Amine Systems.
Abstract
A low molecular weight epoxy resin was cured isothermally with an aromatic amine hardener, and the ionic conductivity was measured as a function of frequency, reaction time and cure temperature. At specific stages in the cure small samples from the reacting mixture were quenched, and then analyzed for the glass transition temperature and epoxy group conversion by differential scanning calorimetry. In this manner changes in ionic conductivity could be directly correlated with the build-up of network structure during polymerization. The conductivity was modeled as a function of the cure temperature and the cure-dependent glass transition temperature using a Williams-Landel-Ferry (WLF) relation. The behavior of the conductivity for an isothermal curing system was found to be consistent with the WLF behavior of a set of neat epoxy resins of various Tg, but with changing temperature. An empirical DiBenedetto relation was used to correlate changes in epoxy conversion with the glass transition temperature. Combining the DiBenedetto model with the WLF relation for conductivity, the ionic conductivity can be predicted as a function of the epoxy group conversion. (Keywords: Thermoset, Conductivity, Glass transition, Temperature, Williams-Landel-Ferry equation, Differential scanning calorimetry, Epoxy group conversion, Network structure, Microdielectrometry, DiBenedetto equation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 15, 1986
- Accession Number
- ADA177569
Entities
People
- Norman F. Sheppard Jr.
- Stephen D. Senturia
- Sue A. Bidstrup
Organizations
- Massachusetts Institute of Technology