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The modification of local structure of some commercial polyethylene terephthalate (PET) samples, gamma irradiated at different doses, was investigated by X-ray diffraction method before and after thermal treatment. Before the thermal treatment, the samples exposed to different doses of gamma radiations, does not show noticeable structural changes. However, the gamma exposure affects the thermal behavior of samples submitted to melting–cooling process. These modifications have been highlighted by X-ray diffraction, and confirmed also by thermal analysis and electron spin resonance spectroscopy. [ABSTRACT FROM AUTHOR]

Thermal degradation of commercial polystyrene was investigated by XRD and FT-IR metods. The samples were heated 30 minutes at temperatures 140°C, 200°C, 250°C, 300°C and 350°C and then brought back to room temperature. XRD investigation denotes structural modification for samples heated above 200°C. This modification is confirmed by FT-IR measurments. Some vibration bands are affected by thermal degradation at temperatures higher than 200°C. Both FT-IR and XRD methods reveal modification of microscopic structure of the polystyrene submitted to thermal degradation. [ABSTRACT FROM AUTHOR]

The effects of gamma radiation on the local structure of PVA membranes containing TiO were investigated by ESR and XRD methods. An intense ESR signal is observed after irradiation at 16 KGy dose. This signal appears only for irradiated samples and it is associated with the breaking of the polymeric chain, followed by local reorganization of the polymeric segments and the apparition of the unpaired electrons and free radicals. The intensity of the signal decreases with the concentration of TiO, indicating a shielding effect of the dopand. That the modification of local order of the polymeric chains has been modified after irradiation is confirmed by XRD method. [ABSTRACT FROM AUTHOR]