Accession Number : AD0680759

Title :   NANOSECOND PULSE RADIOLYSIS OF POLYSTYRENE AND POLY(METHYL METHACRYLATE),

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Ho,S. K. ; Siegel,Seymour

Report Date : NOV 1968

Pagination or Media Count : 43

Abstract : Polystyrene and poly(methyl methacrylate) (PMMA) containing diphenyl and naphthalene as solutes have been studied by nanosecond pulse radiolysis. Solute negative ions were detected in PMMA but not in polystyrene. Solute triplet states were formed in times short compared with the lifetimes of the solute excited singlet states, whose presence was observed via their fluorescence. G(triplet) values for 0.2 M samples of naphthalene and diphenyl in polystyrene were estimated to be 1.7 and 1.3, respectively. It is also shown that for high concentrations of solute less than 25 percent of the solute triplet states is derived from ion neutralization inside the spur. No evidence of intersystem crossing from solute excited singlet states was observed. Triplet yields in PMMA were smaller than those in polystyrene by a factor of two or more and were strongly affected by other transient species accumulated inprevious irradiations. This latter quenching mechanism appears to involve the precursor, rather than the solute triplet states themselves. Possible modes of solute triplet state formations are discussed, and it is concluded that triplet energy transfer from the solvent is the most probable mechanism. (Author)

Descriptors :   (*STYRENE PLASTICS, *RADIATION CHEMISTRY), (*ACRYLIC RESINS, RADIATION CHEMISTRY), SOLVENTS, BIPHENYL, NAPHTHALENES, FLUORESCENCE, IONS, QUENCHING(INHIBITION), DOSAGE, ULTRAVIOLET SPECTRA, VISIBLE SPECTRA, MOLECULAR ENERGY LEVELS, CONCENTRATION(CHEMISTRY)

Subject Categories : Radiation and Nuclear Chemistry
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE