ESCA and contact‐angle (H2O and CH2I2) measurements are used to follow changes in the surface of poly(ethylene terephthalate) film photooxidized (254 nm radiation in O2) for varying times, followed by aging for as many as three weeks or washing with water. Photooxidation occurs uniformly throughout the outermost 50 Å of the film to give a surface stoichiometry that corresponds to C10O6.6. Oxidation produces mainly carboxyl (acid) and alcohol/phenol groups, carbonyls form after extensive treatment. Low molecular weight products formed by chain scission and oxidation are removed by washing and diffuse into the bulk when aged. Oxidized products in higher molecular weight chains are not removed by washing, but can diffuse into the polymer bulk or reorient because of their chain mobility; therefore they are directed toward the polymer bulk rather than the surface. Extended photooxidation produces a stable oxidized surface more resistant to aging changes. The results are compared with those obtained for poly(ethylene terephthalate) film oxidized in an electrical discharge.
GREGORY J. COURVAL and DEREK G . GRAY. Can. J. Chem. 54, 3496 (1976). Considerable variation in the measurement of polynier-solvent interactions using gc retention data may occur due to kinetic factors, surface excess concentrations of probe vapour, and nonlinear partition isotherms. The kinetic factors. which appear as a flow rate dependence of the retention volume. are anal) sed in terms of a previously reported theoretical model for retention on polymeric stationary phases passing through the glass transition. The predicted linear extrapolations to zero flow rate are obtained for the retention of tz-tetradecane on polystyrene. The variation of this flow rate dependence with temperature and with the thicknesc of the stationary phase are also in qualitative agreement with the theory. A simplified model for the effect of loading on the retention diagram is presented. Non-linear absorption and bulk sorption isotherms result in a dependence of retention volume on sample size, necessitating an extrapolation of the measured retention volumes to zero peak height. The temperature variation of the flow rate dependence, the effect of loading. and the effect of sample size on retention volume are all further complicated by uneven distribution of polymer on suplsort. From scanning electron micrographs of the beads it is evident that 'beading up' of the polystyrene on the glass surface may occur at low loadings, resulting in a non-uniform coating with large areas of the beads uncoated. It is concluded that in order to obtain reliable dava on polymer-solvent interactions using gas chromatography, all of the above-mentioned factors must be coniidered. Chem. 54, 3496 (1976). 11 peut se produire de grandes variations dans les rnesures des interactions polymkre-solvant en se basant sur des donnees de retention en cpg: ces variations proviennent de facteurs cinetiques, de concentrations d'excks au niveau de la surfaces et d'isothernies de partition nonlineaires. On analqse les facteurs cinetiques, qui apparaissent par une dependance des volumes de retention sur les vitesses d'ecoulernent, en termes du modi-ie thiorique rapport6 anterieurenient pour la retention sur des phases stationnaires sous forme de polymkre passant h travers une transition de verre. Comme prevu, on obtient des extrapolations lineaires sur une vitesse d'Ccoulement de r i r o pour la retention de 11-tttradCcane sur du poljst!,rkne. La variation de la vitesse d'Ccoulement avec la temperature et avec i'epaisseur de la phase stationnaire est aussi en accord qualitatif avec la theorie. On presente un modkle simplifii de 19efTet du chargement sur le diagramme de retention. Les isothernies nonlineaires d'absorption et de sorbtion de masse conduisent i une dipendance du v o l~~m e de retention sur la grosseur de l'echantillon et ceci necessite une extrapolation des volumes de retention niesurCs vers Line valeur nulle pour la hauteur des pics. De plus la \ariation avec la temperature dc la dependance de la vitesse d'icoulement ainsi que I'effet du chargenient et I'ei...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.