Title page for ETD etd-11082006-133622
|Type of Document
||Ellison, Matthew M.
||Metal/polymer interactions in polyimide adhesives
|Taylor, Larry T.
|Anderson, Mark R.
|Dillard, John G.
|Hanson, Brian E.
|Wightman, John P.
- Sulfur oxidation
|Date of Defense
Due to their superior thermal and chemical stability,
polyimides are often used as adhesives in hazardous
environments. This study examines the effect of thioether
sulfur in the polyimide backbone on bond strength. X-ray
photoelecton spectroscopy (XPS) and reflectance infrared
spectroscopy indicated that certain metals catalyze the
oxidation of the thioether sulfur. It was believed that
this oxidation could lead to direct metal-oxygen-sulfur
bonds across the polymer/metal interface which would serve
to enhance interfacial strength. Bonds were made using
substrates that were believed to catalyze the oxidation
strongly (steel) and minimally (aluminum). In addition,
non-sulfur containing polyimides with similar Tg were also
studied for comparison. The polymer/metal interface was
studied using both the T-peel and wedge tests. In some cases, oxidized sulfur was detected on the failed surfaces
via XPS. No apparent effect was observed in the T-peel
test, where the T-peel strengths of non-sulfur and sulfur
containing polyimides were similar. In the wedge test,
however, the sulfur containing BDSDA/ODA bonded to steel had
an initial crack length of 34 mm. Even after eleven days
the crack length was only 47 rnm, which was the initial crack
length for the next best polyimide. Thus, metal-catalyzed
oxidation of sulfur did take place, but not to an extent to
have a noticeable effect on peel strength.
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