engleski

Poly(ethylene oxide) irradiated in solid state, melt and aqueous solution - DSC and WAXD study

The interactions of aggregate state of poly(ethylene oxide), PEO and its γ-irradiation conditions (total dose, atmosphere) on thermal and crystalline properties were investigated by DSC and WAXD taking into account sample molecular mass and form. In dose range up to 200 kGy in PEO irradiated in the solid state and in the presence of oxygen, chain scission dominated particularly in PEO powders because of large surface in contact with air. In solid samples the degree of crystallinity and crystallite size increased with dose up to 50 kGy probably due to recrystallization of broken tie molecules, partial crystallization on degradation of amorphous phase could contribute. Slight changes in preferred crystallite orientation confirm the role of tie molecules. These proceses presumably manifest also through slight changes in preferred crystallite orientation. The least changes in crystallinity and temperatures of the phase transformations were attained in solid PEO films. Greater decrease in crystallinity and transformation temperatures without the initial crystallinity increase was achieved in PEO samples irradiated at temperatures above its melting and in aqueous solution. Such radiation crosslinking of the aqueous solution of PEO in an inert atmosphere is the most suitable way to obtain lower degree of crystallinity and phase transformation temperatures while preserving mechanical properties.

poly(ethylene oxide) ; gamma-irradiation ; degradation ; crosslinking ; crystallinity ; DSC ; WAXD ; aggregate state ; crystallite size ; crystallite orientation

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