Low dose γ‐irradiation of some fluoropolymers: Effect of polymer chemical structure

Wiley - Tập 45 Số 5 - Trang 783-795 - 1992
Y. Rosenberg1, A. Siegmann1, M. Narkis2, S.M. Shkol'nik3
1Department of Materials Engineering, Technion, Haifa 32000
2Department of Chemical Engineering, Technion, Haifa 32000
3Soreq Nuclear Research Center, Yavne 70600, Israel

Tóm tắt

AbstractThe effect of low dose (1–20 Mrad) γ‐irradiation on five fluoropolymers (PVF, PVDF, ETFE, FEP, PFA), differing in fluorine content and chain structure, was studied. The radiation effect, reflected by changes in thermal and mechanical properties, as well as NaOH etched surface morphology, was investigated. The main chain structure was found to predominate the irradiated polymers' behavior. The tensile strength of PVF and its resistance to etching increased with radiation dose, while its degree of crystallinity and melting temperature decreased. These changes were correlated with network formation by irradiation and by the incorporation of crosslinked segments into the crystalline phase during recrystallization. Solvent extraction of PVDF (no solvents were found for the other fluoropolymers) revealed increased gel formation with increasing dose. The degree of crystallinity and the tensile strength dependence on radiation dose for PVDF and ETFE reflected the competition between crosslinking and chain scission events. FEP and PFA undergo predominantly chain scission accompanied by reduction of their mechanical properties. PFA even exhibited an increase in both its melting temperature and degree of crystallinity, stemming from a massive degradation process forming shorter chains. Chemical mechanisms are discussed in an attempt to correlate the irradiation effects with the polymers' chain structure.

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Wiley

Tập 45 Số 5

783-795

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