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Density–dose behavior of irradiated polytetrafluoroethylene
Author(s) -
Scherer A. E.,
Kline D. E.
Publication year - 1967
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1967.070110303
Subject(s) - irradiation , materials science , radiation , polytetrafluoroethylene , percentage depth dose curve , radiation effect , range (aeronautics) , nuclear medicine , radiochemistry , neutron , chemistry , composite material , optics , nuclear physics , medicine , physics , ionization chamber , ion , organic chemistry , ionization
The nature of the room temperature density–dose relationships in polytetrafluoro‐ethylene (PTFE) have been studied over the dose range of 10 4 to 10 9 rads. Under various conditions, samples of PTFE were irradiated in combinations of neutron and gamma (reactor and 60 Co) radiation fields resulting in density increases up to approximately 5%. For the dose range 10 5 to 10 8 rads, the increase in density measured at 0°C. is approximately proportional to the logarithm of the radiation dose. For doses less than about 10 5 rads, the increase in density appears to be directly proportional to the dose, while above 10 8 rads the density reaches a maximum and then begins to decrease. By examining the changes in slope and displacement of the curves which occur under various conditions, several effects are discernible. Compared to the effects of γ‐rays alone, the density increase per dose in the 10 5 to 10 8 rad region is lower for cases where both neutrons and γ‐rays are present in the radiation field. This may suggest that competing processes are involved in producing density changes. The discernible difference between effects of γ‐radiation and reactor radiation appears to be unique in polymers. The ambient temperature during irradiation and the post‐irradiation heat treatment of the specimens affect the changes in density. For dose rates over the range 0.1 × 10 6 to 13 × 10 6 rads/hr., no dose rate effects have thus far been observed. The feasibility of using PTFE for some types of radiation dosimetry has been demonstrated, and its possible usefulness is being investigated.