THE EFFECTS OF SPACE ENVIRONMENTS ON INSULATION OF TEFLON (TRADE NAME) TFE AND FEP RESINS
DU PONT DE NEMOURS (E I) AND CO WILMINGTON DE PLASTICS DEPT
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Teflon TFE and FEP resins do not evaporate in a vacuum of 10 to the minus 7th power mm Hg. Theoretical calculations indicate that these resins will not evaporate in any anticipated space vacuum to an extent which would put a practical limit on their usefulness. Although some outgassing occurs initially, the volatiles are all absorbed atmospheric gases. The presence of oxygen greatly influences the physical and electrical properties of irradiated Teflon TFE and FEP resins when irradiated above an approximate value of 40,000 rads. With proper design considerations, Teflon TFE resins maintain their usefulness after radiation dosages of at least 10 to the 7th power rads in the absence of oxygen. Teflon FEP resins, when irradiated in the absence of oxygen and above 80C show an improvement in certain desirable physical properties with doses greater than 2,600,000 rads. An upper dose limit for this material cannot be predicted because of lack of adequate data. Low frequency loss properties of Teflon TFE polymers are drastically affected by x-ray irradiation. High frequency loss properties are considerably less affected. The increases in dielectric constant and dissipation factor depend upon the ambient oxygen concentration during exposure and recovery. The dielectric constant and dissipation factor of Teflon FEP resins are unaffected by x-ray irradiation in vacuum for measured frequencies of 60 cps to 100 kcps.
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