Structure Within Thin Epoxy Films Revealed by Solvent Swelling [electronic resource] : A Neutron Reflectivity Study
- Washington, D.C. : United States. Dept. of Energy, 1999.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
- Physical Description:
- 32 pages : digital, PDF file
- Additional Creators:
- Sandia National Laboratories
United States. Department of Energy
United States. Department of Energy. Office of Scientific and Technical Information
- Structure within thin epoxy films is investigated by neutron reflectivity (NR) as a function of resin/crosslinker composition and cure temperature. Variation in the crosslink density normal to the substrate surface is examined by swelling the films with the good solvent d-nitrobenzene (d-NB). The principle observation is a large excess of d-NB near the air surface. This is not a wetting layer,but rather indicates a lower crosslink density in the new-surface region. This effect is due to preferential segregation of the crosslinker to the air surface, driven by the lower surface energy of the crosslinker relative to the epoxide oligamers. The magnitude of the effect is a function of composition and cure temperature. Exclusion of d-N13from the region immediately adjacent to the substrate surface is also observed, possibly indicating a tightly bound layer of epoxy. Regarding swelling in the bulk of the films, the behavior is non-symmetric with departure from the stoichiometric ratio. The films deficient in curing agent show greater equilibrium swelling and faster swelling kinetics than the films with an excess of curing agent.
- Published through SciTech Connect.
Majewski, J.; Kent, M.; Satija, S.; Yim, H.; McNamara, W.F.; Ivkov, R.
- Funding Information:
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