Rad damage to teflon and PTFE -Reply

[FRAMEP@ORAU.GOV]

Jeff:

Quoting Bolt & Carroll's "Radiation Effects on Organic Materials":"Teflon
and Kel-F are among the most sensitive [polymers]to radiation in the
presence of oxygen. Even with thick specimens, irradiation in air causes
rapid deterioration of mechanical properties.""The tensile strength of 0.14
in. specimens of teflon was reduced to half...at about 4 E6 rads".

Quoting Kircher and Bowman's "Effects of Radiation on Materials and
Components" regarding these materials" Fluorinated materials do not
crosslink but instead the fluorine atom is liberated and reacts to break a
carbon-to-carbon bond which contributes to the poor resistance of
fluoroethylene polymers to radiation" "The rapid degradation of
polytetrafluoroethylene..can be attributed chiefly to the prevalence of
main chain scission by liberated fluorine atoms and the production of
entrapped fluorocarbon gases." ..."threshold damage fot Teflon as 1.7E6
ergs per gram and 25% damage as 3.4 E6 ergs per gram.....tensile
strength of Teflon decreases by 40% after a dosage of 3 E8 ergs per
gram while the elongation decreases by 93%...."dielectric constant of
specimens ranging in thickness from 3 to 125 mils showed no significant
change after.. 5.0 E9 ergs per gram."

This might not help but it was the best I could locate. Good luck

Paul Frame
Professional Training Programs
ORISE
framep@orau.gov