Published online by Cambridge University Press: 02 July 2020
The fact that there is a region at the epoxy/adherend interface known as the interphase whose chemistry and structure are different from that of bulk epoxy is well established (1-2). The specific nature of the interphase depends on the resin and curing agent, the adherend surface-chemical properties, and the adherend sizing treatment if any, among other possible variables. The interphase is critically important, since it is responsible for stress transfer between the matrix and reinforcing fibers. While it has been studied by a variety of analytical methods (eg. 3-5), none have had sufficient spatial or spectral resolution to establish the physical extent of the interphase or its compositional deviation from bulk epoxy. This research exploits high-spatial-resolution analysis in a field-emission STEM to study the interphase in epoxy/adherend systems using high-angle electron scattering (HAADF-STEM) and energy-loss spectroscopy (PEELS).
Thin specimens were cut by ultramicrotomy using a diamond knife from single-fiber tensile bars consisting of anodized aluminum wire embedded in an epoxy matrix (Fig 1.)