The effect of electron irradiation on the mechanical properties (deformability) of polyethylene terephthalate (PET), polytetrafluoroethylene ( PTFE ), polyimide ( PI ), and Fenilon ( Fe ) The effect of ionizing radiation on the properties of polymer materials depends on the features of the macromolecular structure of the initial substance, its phase state, the conditions of irradiation, and other factors. Electron irradiation considerably modifies the l$olymer structure, namely the latter is transformed from the linear to the three-dimensional state, its molecular m~.qs increases or decreases, free radicals are initiated and annihilated, etc. Needless to say that all these factors greatly affect the properties of the polymers [I].This study deals with the effect of electron irradiation on the mechanical properties of industrially produced polymer films of polyethylene terephthalate (PET), polyJmide (PI), polytetrafluoroethyiene (PTFE), and Fenilon (Fe) of thickness h no less than 50 ~m and the thermophysical properties of PTFE of thickness h = 2 ram.For the mech~nlcal tests, samples of the films in the form of 10 x 200 mm 2 strips were placed in a special cartridge. The samples were separated by spacers to ensure better removal of heat. For uniform irradiation, the samples were interchanged at regular time intervals. Irradiation was carried out with electrons of 2 MeV up to absorbed doses of 1, 10, 30, and 100 MGy. The temperature conditions for each type of sample was adjusted by electron beam current with appropriate cooling and did not exceed 25-30~The mechanical characteristics were determined by standard methods after accumulation of specified absorbed doses. Both unirradiated and irradiated polymer films were tested in tension. The mechanical tests were performed with automatic recording of the load-deformation curves. Figure 1 shows the graphs of this dependence for four types of polymer films, whereas the variation of the dependence for the different radiation doses absorbed by the PET film is given in Fig. 2. The results of processing the mechanical tests are shown in Fig. 3 as the dependence of the rupture stress ~f and relative strain sf in tension on the absorbed dose of electron radiation.The experimental results show that the polyethylene terephthalate film is the strongest of the unirradiated polymer films. In PET and Fe films, the yield point is very pronounced. As the data in Fig. 2 Abed Alma-Ata State University, Kazakhstan.

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