Radiation-thermal modification of fluoroplastic composite and evaluation of its radiation-protective characteristics

Abstract

In the work the composite on the basis of fluoroplastic with filler WO₃ is studied and its efficiency for protection against X-ray and gamma radiation is proved. The technological scheme of composite production has been developed and its physical and mechanical characteristics have been studied. The composite with 60 wt% of WO₃ content has the following properties: density 3.35 ± 0.02 g/cm³, Vickers microhardness (at 300 g load) 5.38 ± 0.32 HV, flexural strength 18.86 MPa. The γ-radiation sources used were E(²⁰⁷Bi) = 0.570 MeV with an activity of 50 kBq, E(¹³⁷Cs) = 0.662 MeV with an activity of 9 kBq, and E(⁶⁰Co) = 1.252 MeV with an activity of 100 kBq. The X-ray radiation sources were isotopes ²⁴¹Am (half-life T_1/2 = 432.1 years; photon energy E = 59.5 keV; radioisotope activity 46 μCi) and ¹⁰⁹Cd (half-life T_1/2 = 461.4 years; photon energy E = 88 keV; radioisotope activity 15 μCi). It is shown that for reduction of gamma radiation with energy 1.252 MeV by 50 % a screen from pure fluoroplastic with thickness of 6.301 ± 0.654 cm is required, and for composite with 60 wt% WO₃ the thickness of screen is 1.5 times less (4.077 ± 0.509 cm). Comparison of the linear attenuation coefficient at energy 0.662 MeV with modern analogs confirmed the high efficiency of radiation protection of the developed material. Radiation-thermal modification of the samples was carried out, which allowed to increase their radiation resistance to gamma radiation many times. After radiation-thermal modification the radiation resistance increased up to 1 ± 0.1 MGy and 4.5 ± 0.2 MGy for fluoroplastic and composite with 60 wt% WO₃ content, respectively. And the initial bending strength increased in both materials by 15 % and more.