Flow-induced fiber orientation in cellulose nanofiber suspension flow through a small channel with a complex geometry

Distributions of fiber orientation and fiber concentration in slit flows of concentrated suspensions were measured. Slit channels were used in the experiments: a channel with an abrupt expansion and a crank geometry with six L-shaped corners. Such channels are usually used in a polymer processing. For visualization of fibers, an index-of-refraction matching method was employed, and tracer fibers having birefringence were suspended to observe between crossed polarizers. When fibers flow through an abrupt expansion, they rapidly orient in the direction perpendicular to the flow direction near the centerline. The fiber orientation, however, returns to the flow direction in the downstream region. In the L-shaped corner, fibers randomly orient because of the decelerating flow. In the downstream region of the L-shaped corner, fiber orientation is not symmetric with respect to the centerline. This seems to result from fiber-fiber interactions in the concentrated suspension. The fiber concentration is uniform over a width of a channel except adjacent to the side wall in the concentrated suspension, while it has a maximum apart from the side wall in the dilute suspension.

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Numerical solution of fiber suspension flow through a parallel plate channel by coupling flow field with fiber orientation distribution

Journal of Non-Newtonian Fluid Mechanics ◽

10.1016/s0377-0257(01)00118-5 ◽

2001 ◽

Vol 99 (2-3) ◽

pp. 145-157 ◽

Cited By ~ 29

Author(s):

Kunji Chiba ◽

Kazunori Yasuda ◽

Kiyoji Nakamura

Keyword(s):

Flow Field ◽

Fiber Orientation ◽

Parallel Plate ◽

Orientation Distribution ◽

Fiber Suspension ◽

Suspension Flow ◽

Fiber Orientation Distribution ◽

Fiber Suspension Flow ◽

Flow Through ◽

Plate Channel

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Orientation and Concentration Distributions of Short Fibers in Concentrated Suspension Flow through a Slit Channel with a Sudden Expansion: Effects of Fiber-Fiber Interaction and Polymer.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C ◽

10.1299/kikaic.67.3363 ◽

2001 ◽

Vol 67 (662) ◽

pp. 3363-3369

Author(s):

Kazunori YASUDA ◽

Kiyoji NAKAMURA ◽

Noriyasu MORI

Keyword(s):

Suspension Flow ◽

Sudden Expansion ◽

Short Fibers ◽

Concentrated Suspension ◽

Slit Channel ◽

Flow Through ◽

Fiber Interaction

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Fiber Orientation Control by Stretching in Cellulose Nanofiber Green Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.754.135 ◽

2017 ◽

Vol 754 ◽

pp. 135-138

Author(s):

Hitoshi Takagi ◽

Antonio Norio Nakagaito ◽

Yuya Sakaguchi

Keyword(s):

Fiber Orientation ◽

Vinyl Alcohol ◽

Glass Fibers ◽

Cellulose Nanofibers ◽

Polymeric Composite ◽

High Strength ◽

Sample Surface ◽

Cellulose Nanofiber ◽

Poly Vinyl Alcohol ◽

Nanofiber Alignment

The presence of nanoscale cellulosic fiber; namely cellulose nanofiber, increases year by year because the mechanical and physical properties are believed to be comparable to those of common glass fibers. On the other hand, most of the reported strength data for the cellulose nanofiber-reinforced polymeric composite materials was not as high as expected. In order to obtain high-strength cellulose nanofiber-reinforced polymer composites, we tried to optimize the fiber orientation of cellulose nanofibers in poly (vinyl alcohol)-based polymer matrix by using a repeated mechanical stretching treatment. The fiber orientation of cellulose nanofibers in the poly (vinyl alcohol) matrix can be modified by changing the total amount of stretching strain applied during the multiple stretching treatments. The degree of fiber alignment was directly evaluated by observing the cellulose nanofibers on the sample surface with a digital microscope. The efficacy of proposed nanofiber alignment control has been explored experimentally and theoretically. The tensile strength and modulus of the cellulosic nanocomposites after applying the multiple stretching treatments increased by approximately 80% and 40% respectively, as compared with those of the untreated nanocomposites.

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