Irradiation of some polysiloxanes in various gases

The changes produced by γ‐irradiations on two polysiloxanes in several gaseous atmospheres were studied by both sequential and parallel exposures with an in‐situ vibrating reed technique. Irradiation in atmospheres of N 2 O, He, air, and a mixture of 20% NO 2 and 80% N 2 , caused reduction in the crosslinking rates of the polymers as compared to vacuum. Marked discolorations of the samples occurred when irradiations were conducted in air, N 2 O, and 20% NO 2 –80% N 2 . Similarities in crosslinking rates and color changes were obtained when the polymers were irradiated in either air or the gas mixture.