TIT# Variation of PVDF morphology due to radial cold flow in a flexible pipe
AUT# Aquino, Fabio; Stribeck, Almut; Li, Xuke; Zeinolebadi, Ahmad;
     Buchner, Stefan; Santoro, Gonzalo;
SOU# Polym. Eng. Sci. (2015), submitted
LOC# xv144
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MAT#
ABS# A subsea flexible pipe has been subjected to cyclic rapid decompression.
     The poly(vinylidene fluoride) (PVDF) layers have flowed radially into
     gaps of adjacent metallic coils forming whitened noses. Microbeam
     small-angle X-Ray scattering (SAXS) scanning is applied. PVDF layers
     (inner: wear, outer: barrier) in two zones (undamaged and damaged) are
     tested. Far from noses and damage zone the samples are isotropic without
     voids. Their morphological parameters are determined and compared to
     virgin material. Approaching the noses, the structure turns into highly
     oriented microfibrils perpendicular to the local flow into the gaps. Here
     voids extend parallel to the microfibrils. At edges of the metallic
     structure they turn more perpendicular to the layer. Crystallite
     orientation extends out to both sides of the whitened nose regions, but
     in the undamaged samples tilting of the orientation direction and
     void-formation are restricted to the white regions: successive mechanisms
     of cold drawing are mapped into space Under the damaged spot voids and
     crystallite orientation are observed everywhere.