On the microstructure of the epoxy/adherend interphase

M. Libera, W. Zukas, S. Wentworth, A. Patel

Research output: Contribution to journalConference articlepeer-review

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Abstract

It is now recognized that there is a region at the epoxy/adherend interface known as the interphase whose chemistry and structure are different from those of bulk epoxy. There is, however, no adequate understanding of its microstructure. This paper describes differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) studies of the interphase between an aromatic amine cured epoxy and alumina/oxidized-aluminum surfaces. DSC results show dramatic differences in resin-cure behavior in the presence of particulate alumina. TEM results on microtomed cross-sectional specimens of anodized aluminum wire embedded in epoxy show regions of incomplete epoxy infiltration and interfacial stress. RuO4 staining combined with high-angle annular-dark-field STEM imaging indicates that there are structural variations within the bulk epoxy at lengths of approx. 10-30nm. The magnitude of these fluctuations decreases in the near the adherend interface, and there is a simultaneous variation in the average epoxy structure. A plausible interpretation of these observations is that the interphase region suffers a variation in curing-agent concentration of unknown magnitude and there is a higher concentration of homopolymerized epoxy there relative to the bulk.

Original languageEnglish
Pages (from-to)65-70
Number of pages6
JournalMaterials Research Society Symposium Proceedings
Volume385
DOIs
StatePublished - 1995
EventProceedings of the 1995 MRS Spring Meeting - San Francisco, CA, USA
Duration: 17 Apr 199520 Apr 1995

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