The d.c. conductivity and the dielectric constant of an epoxy resin cured with a diamine were examined in a frequency interval extended up to 10" Hz. The analysis of the dielectric behavior has permitted gaining a better knowledge of the relationships between dielectric parameters and the physical a
Surface Energetics Evolution during Processing of Epoxy Resins
✍ Scribed by Stéphane A. Page; Raffaele Mezzenga; Louis Boogh; John C. Berg; Jan-Anders E. Månson
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 123 KB
- Volume
- 222
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
The surface energetics evolution throughout the entire curing process of two epoxy resins is predicted using a previously developed semiempirical relationship between surface tension and the solubility parameter. Evolution of the temperature and time of both the solubility parameter and density is investigated and used for this prediction, as is the concept of molar volume or mass of the interacting element. The theoretical prediction is compared with measured surface tensions. Experimental data are determined at different times during an isothermal curing process by the Wilhelmy wetting force method for surface tension with viscous drag corrections. Once corrections for viscous effects on measured surface tensions are made, very good agreement is found for the surface energetics evolution. Moreover, the total surface energies of solid cured epoxy resins, which cannot be directly measured, can be estimated with this prediction. Finally, this study provides a tool for further understanding the final adhesive properties of polymeric material considering the time evolution of surface energetics during processing.
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## Abstract Variations in electrical properties of epoxies during polymerization permit interpretation of molecular changes occuring. Three liquid epoxy resins selected for test were of different molecular weights, varying from 6,400 to 26,800 cycles/sec. Curing agents selected included triethylene