Ionic changes, glass transition temperature

Novel sulfonated and carboxylated ionomers having "blocky" structures were synthesized via two completely different methods. Sulfonated ionomers were prepared by a fairly complex emulsion copolymerization of n-butyl acrylate and sulfonated styrene (Na or K salt) using a water soluble initiator system. Carboxylated ionomers were obtained by the hydrolysis of styrene-isobutyl-methacrylate block copolymers which have been produced by carefully controlled living anionic polymerization. Characterization of these materials showed the formation of novel ionomeric structures with dramatic improvements in the modulus-temperature behavior and also, in some cases, the stress-strain properties. However no change was observed in the glass transition temperature (DSC) of the ionomers when compared with their non-ionic counterparts, which is a strong indication of the formation of blocky structures. 

If the polymeric material is in the glassy state, that is, below the glass transition temperature (Tg) or has some crystallinity, trapped electrons and trapped radicals can be produced upon irradiation with either electron beam or y-irradiation. Phenomena such as thermoluminescence, electrical conductivity, color changes in the polymer, and imperfections within crystals have attributed to ionic species. Trapped electrons have been identified in y-irradiated polyethylene [46]. 

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