DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click
HERE to register or log in.
Accession Number:
ADA210362
Title:
An Investigation of the Degradation and Stabilization of Polymer Systems
Descriptive Note:
Final rept.
Corporate Author:
UNIVERSITY OF SOUTHERN MISSISSIPPI HATTIESBURG DEPT OF POLYMER SCIENCE
Report Date:
1989-07-14
Pagination or Media Count:
6.0
Abstract:
The project on Investigation of the Degradation and Stabilization of Polymer Systems concentrated primarily on a detailed study of the factors which effect the photolytic decomposition of polyurethanes based on aromatic diisocyanates. An extensive investigation of the photophysics of 1,5-naphthalene diisocyanate based polyurethanes in solution was also conducted. In addition, ground work was laid to initiate studies on the photodegradation of polycarbonate, polyureas, and polymides. Employing both steady and time resolved fluorescence spectroscopy to analyze the photolysis products of model compounds and polyurethane films, photo-Fries and other cleavage products were identified at the very early stages of photolytic induced decomposition. We also clearly established the critical effect of polymer main-chain flexibility, crystalline content, and hydrogen bonding on the extent of degradation of polyurethane films and coatings. Laser flash photolysis results confirmed the contribution of peroxide and aromatic ketone impurities incorporated into all commercial polyurethanes during the synthesis and processing steps to the photodegradation process. For methylene 4,4-diphenyl diisocyanate MDI based polyurethanes, transient spectra of diphenyl methyl radicals were detected under a variety of conditions, thus providing unequivocal evidence for one of the primary modes of the initial stages of photooxidation of segmental polyurethane elastomers.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
