Free radicals in irradiated polyacrylonitrile synthesized under high pressure

Using as an example polyacrylonitrile (PAN), the effect of structural differences between polymers synthesized under different hydrostatic pressures on the formation and properties of free radicals in irradiated polymers is investigated. PAN was irradiated by 60Co γ-radiation with the dose rate 0.9 mrad/H at 77 and 300 K. All PAN samples, irradiated at 77 K, provided similar ESR spectra. Free radicals, formed in PAN, γ-irradiated at 300 K and synthesized at high pressures (to 500 MPa), differ considerably as to the storing concentration, and stability from free radicals in PAN, synthesized at atmospheric pressure. The higher the PAN synthesis temperature is, the lower is their threshold concentration