Re: Rad damage to teflon and PTFE -Reply

[chatho@roadrunner.com (Charles Thomas)]

>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
>
These were the two references that I intended to look up for you.  Thanks to
Paul that is no longer necessary.  These are about the best references Ihave.
Charles C. (Tommy) Thomas
3373 Avenida San Marcos
Santa Fe, NM  87505-9210
Phone/Fax 505-471-9048
e-mail chatho@roadrunner.com or chatho@lanl.gov
Approved by the Boss - M. S. Thomas