Photoradiation processes in combined polymeric materials

The methods of ESR, optical and mass-spectroscopy have been used to study the formation and decay of active intermediates. radiation and photoradiation gas evolution in a series of combined polymeric materials, The investigated samples were films of polyimide (PI). one- or two-side coated PI-fluoroplast, poly(ethylene terephthalate) (PET), PET coated with polyacryl on both sides, etc. Different coatings and polymeric substrates have been established to produce a mutual effect on the radiation- and photo-induced transformations of the combined polymers at the stage of radical Formation and gas evolution. Thus, gamma -irradiation of PI-fluoroplast films at 300 K intensifies the radiation-chemical processes in the fluorinated coatings, namely. the radiation-chemical yield of macroradicals in the coatings is several times higher than that in fluoro-containing polymers. In the PET film coated with polyacryl the yield of macroradicals related to polyacrylic acid is significantly louver than the value generally cited in the publications. A mutual effect of the coatings and substrates on the radiation and photoradiation-induced gas evolution is even more noticeable. Thus, a gas mixture of the PI-fluoroplast film contains lower amounts of carbon oxide and fluorinated products and no hydrogen at all, The interphase processes, distortion of the boundary layer structure. electronic equilibrium. mutual effect of the evolved gases. etc. can account for the reasons of such non-additivity. (C) 2001 Published by Elsevier Science B.V.