Accession Number : AD0649738

Title :   PHOTODEGRADATION OF HIGH POLYMERS IN SOLUTION. PART IV. THE EFFECT OF ADDITIVES ON THE PHOTOLYSIS OF POLY(METHYL METHACRYLATE).

Descriptive Note : Interim rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Fox,Robert B. ; Price,Thomas R.

Report Date : 10 MAR 1967

Pagination or Media Count : 23

Abstract : Poly(methyl methacrylate) was photolyzed by 2537A radiation at room temperatures in methylene chloride and in dioxane. The quantum yields for random scission in the absence of air in dioxane were 0.168 scission/quantum absorbed at an intensity absorbed by the polymer of 0.30 X 10 to the 16th power quanta/ml-min; in methylene chloride the corresponding data are 0.149 and 0.27 x 10 to the 16th power. The quantum yields in the presence of air are about half these yields. A wide variety of chemical additives in the polymer solutions were sensitizers or inhibitors of degradation. The strongest inhibitors were those additives whose lowest excited triplet levels were below about 23,000/cm, and the sensitizers were those additives whose lowest excited triplet levels were above 27,000/cm. By postulating electronic energy transfer via the lowest excited triplet levels as the mechanism for inhibition or sensitization a triplet is inferred for the polymer between 23,000 and 27,000/cm. As further evidence of this postulate a number of nitro compounds which would be expected to form triplets were found to show promise as inhibitors to the poly(methyl methacrylate) photolysis. (Author)

Descriptors :   (*POLYMERS, DEGRADATION), (*ACRYLIC RESINS, *PHOTOLYSIS), SOLUTIONS(MIXTURES), ADDITIVES, PHOTOCHEMICAL REACTIONS, ULTRAVIOLET RADIATION, CHEMICAL BONDS, SENSITIVITY, INHIBITION, MOLECULAR ENERGY LEVELS, EXCITATION, STABILIZATION

Subject Categories : Radiation and Nuclear Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE