Effect of radiation on the melting behavior of polytetraoxane obtained by γ-ray induced-polymerization in the solid state

It was found that the irradiation on polytrioxane caused meridional scattering streak in small angle X-ray scattering patterns, while unirradiated polytrioxane does not show meridional scattering in SAXS patterns. The SAXS patterns of polytetraoxane obtained after the polymerization in solid state showed meridional scattering, and it indicates the existence of long spacing period in the direction of the C-axis of polymer crystals. The polytetraoxane prepared by the γ-ray-induced postpolymerization of tetraoxane in solid state was irradiated with γ-ray at room temperature, and its melting behavior was investigated. The profile of the endothermic valleys at melting in heating curves was similar in every sample irradiated with the dose below 10 MR, while the temperature at which melting started shifted to lower temperature as the dose increased. The irradiation with the dose of 50 MR or more caused remarkable change in the profile of the endothermic valleys at melting, and it indicates the destruction of the polymer crystals. After the irradiation of 300 MR, radiation damage was produced significantly in the crystals, though the apparent morphology of the original sample was kept. Small angle and wide angle X-ray scattering patterns varied little with the change of irradiation dose, and it indicates no significant crystallographic change by the irradiation. (Kako, I.)