Early stages of cavitation in a stretched and decompressed poly(vinylidene fluoride) exposed to diffusive hydrogen, observed by Transmission Electronic Microscopy at the nanoscale

Michel Gerland (1) , Séverine A.E. Boyer (1) , Sylvie Castagnet (1)

1 PPrime [Poitiers] - Institut Pprime [UPR 3346]

Early stages of cavitation were addressed in a semi-crystalline polymer submitted to stretching and/or decompression in hydrogen environment. Both types of loadings were examined thanks to variable test histories. The semi-crystalline specimen was an alpha-poly(vinylidene fluoride) exposed to hydrogen pressure of 4 MPa at constant temperature of 30 °C. Tracking of cavities onset was assessed from fine TEM micrographs analysis at the nanometric scale on ultracryo-microtomed surfaces. Cavitation morphology is heavily influenced by adjusting hydrogen decompression and tensile deformation. Decompression leads to the nucleation of nanobubbles (a few nanometers in diameter), rather independent on large cavities nucleated by tension. They may coalesce if tension if applied after decompression. The most severe situation is obtained when decompression is applied to stretched samples.

Mots clés: PVDF; Hydrogen; Cavitation; TEM; Tension

Domaines: Physique [physics]; Sciences de l'ingénieur [physics]

Michel Gerland, Séverine A.E. Boyer, Sylvie Castagnet. Early stages of cavitation in a stretched and decompressed poly(vinylidene fluoride) exposed to diffusive hydrogen, observed by Transmission Electronic Microscopy at the nanoscale. International Journal of Hydrogen Energy, 2016, 41 (3), pp.1766-1774. ⟨10.1016/j.ijhydene.2015.11.015⟩. ⟨hal-03656506⟩