平面急縮小流路を通過するセルロースナノファイバー分散系流体の秩序性変化に関する実験的研究

抄録

Flow-induced ordered-state changes of TEMPO-oxidized cellulose nanofiber (CNF) suspensions were experimentally investigated in flows through a planar channel with an abrupt contraction. Three types of planar channels with an abrupt contraction (contraction ratio = 4) were used to measure anisotropic parameter (DO: degree of order) by optical observation. Furthermore, velocity profiles were measured by particle-tracking velocimetry in order to investigate their flow properties. The DO at the centerline around the contraction rose steeply. Moreover, the DO after the abrupt contraction did not agree with that upstream, and a relatively high DO was maintained in the downstream region. To gain deeper insight into the experimental results, elongational rates were estimated from velocity profiles. These rates dropped to approximately zero after the abrupt contraction. The viscosity was modeled by the power-law relation to fit the predicted velocity profiles to the measurements. Because neither shear nor elongational action was present, relatively high DO at the centerline was maintained.