
Session D40 - Poster Session I.
POSTER session, Monday afternoon, March 12
Exhibit Hall, Washington State Convention Center
Durability of polymeric coatings is investigated by using positron annihilation spectrscopy and gloss measurements in a variety of commercial coatings and model polyurethane under UV irradiation of both accelerated and natural weathering conditions. Significant variations of sub-nanometer defect parameters determined from PAS results are observed as a function of depth, of exposure time, and of weathering conditions. The loss of durability at the early stage of UV irradiation is interpreted in terms of photo-oxidation mechanism which involves the change of surface roughness and chemical structures. This is correlated with results obtained using glossiness and cross-linking dennsity measurements.
* Supported by NSF-CMS-9812717; AFOSR:F49629-97-0162,F49629-98-1-0309