Accession Number : AD0698918

Title :   THE PHOTO-OXIDATION OF POLYPROPYLENE: SOME EFFECTS OF MOLECULAR ORDER,

Corporate Author : NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO) DIV OF APPLIED CHEMISTRY

Personal Author(s) : Kato,Y. ; Carlsson,D. J. ; Wiles,D. M.

Report Date : 05 FEB 1969

Pagination or Media Count : 12

Abstract : Fractional crystallization was used to separate a commercial, predominantly isotactic, unstabilized polypropylene into fractions of relatively low and relatively high atacticity, but of similar molecular weight. IR spectroscopy was used to follow the photo-oxidations of films formed from these fractions during irradiation in air with light of wavelengths greater than 3000 A. The major oxidation products included hydrogen-bonded hydroperoxides and carbonyl compounds. Films of constant tacticity, but varying morphology were prepared by quenching from the melt. No distinct correlation was found between sample photostability and morphology, as indicated by film density. Films of low atactic content were found to undergo faster photo-oxidation than films of high atactic content, irradiated under identical conditions. This effect is believed to be due to the occurrence of a stereo-dependnt step (or steps) in the oxidative chain, and not due to differences in sampling morphology. The possible nature of the stereo-dependent steps is considered in terms of well-established oxidative chain processes. The effects of polypropylene polymorphism on oxygen permeability are briefly considered. (Author)

Descriptors :   (*POLYMERS, *OXIDATION), POLYETHYLENE PLASTICS, PHOTOCHEMICAL REACTIONS, FILMS, STEREOCHEMISTRY, INFRARED SPECTRA, FREE RADICALS, ALDEHYDES, CANADA

Subject Categories : Polymer Chemistry
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE