Radical processes induced in poly(siloxaneurethaneureas) by ionising radiation

The effect of ionizing radiation on poly(siloxaneurethaneureas), comprising the soft phase of poly(dimethylsiloxane) chains and hard urethane segments, was examined by electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC). It was found that radical processes in the investigated polymers were determined predominantly by polysiloxane segments. Dehydrogenation proceeded mainly in the terminal groups of dimethylsiloxane sequences, forming methylene radicals, whereas abstraction of methyl group dominated in inner fragments of the polysiloxane chain. However, upon irradiation no change in glass transition temperature of polysiloxane segments was detected by DSC.