Electron beam curing of epoxy resins by cationic polymerization
- Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States)
- Oak Ridge Institute for Science and Education, TN (United States); and others
A Cooperative Research and Development Agreement (CRADA) sponsored by the Department of Energy Defense Programs and 10 industrial partners has been established to develop high performance Electron Beam (EB) curable polymer matrix composites. EB curing of composites has a number of advantages over conventional thermal curing. Composites cured by EB have much shorter cure times, lower overall energy requirements, and reduced thermal stresses in the cured part. Furthermore, less expensive tooling can be used since the process occurs at lower temperatures. Preliminary investigations have determined that conventional epoxy resins can be cured at selectable temperatures with high glass transition temperatures (essentially the same as with thermal curing), while still exhibiting equivalent or comparable mechanical properties. A cationic photoinitiator at a concentration of 1-3 parts per hundred of the epoxy resin is required for this process. Gamma cell screening of cationic photoinitiators with bisphenol A, bisphenol F, and cycloaliphatic epoxies demonstrated that diaryliodonium salts of weakly nucleophilic anions such as hexafluoroantimonate are most effective. Diaryliodonium salts were also found to be the most effective initiators for the cationic polymerization of epoxy resins when a high energy/power electron beam accelerator was used as the source of ionizing radiation. For example Dow Tactix 123 (bisphenol A epoxy) containing 3 phr (4-octyloxyphenyl) phenyliodonium hexafluoroantimonate was irradiated at a total dosage of 100 kGy. Glass transition temperature (tan delta) of the cured material as determined by dynamic mechanical analysis was 182{degrees}C as compared to 165{degrees}C for the thermally cured material.
- OSTI ID:
- 412048
- Report Number(s):
- CONF-960310-; TRN: 96:005072-0013
- Resource Relation:
- Conference: 41. international symposium of the Society for the Advancement of Material and Process Engineering and exhibition: materials and processes challenges - aging systems, affordability, alternative applications, Anaheim, CA (United States), 25-28 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of Society for the advancement of material and process engineering. 41st International SAMPE symposium and exhibition, Volume 41, Books 1 and 2; PB: 1844 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
High energy electron beam curing of epoxy resin systems incorporating cationic photoinitiators
High energy electron beam curing of epoxy resin systems incorporating cationic photoinitiators