Rheology of short-fiber composites: A systematic approach

Rheology of concentrated suspensions containing mixtures of spheres and fibres

“…For large deformations, the viscosity levels off to an equilibrium value. This behaviour is characteristic for nondilute fibre suspensions (Barbosa et al 1994). The rheopectic viscosity increase at the start up of shear flow can be attributed to a combination of following effects.…”

“…(3) Elastic properties in the fibre network caused by strong interactions leads to delayed response of the sheared material. In semi-dilute long fibre systems, increase in viscosity at small strains was found to be proportional on nL 3 , where L is the fibre length and n the number of fibres (Barbosa et al 1994). Furthermore, the maximum viscosity was shown to depend only on total shear deformation and not on the contributions from shear rate and time, separately.…”

“…For an ideally random fibre orientation, each orientation angle is equally possible. If the suspension is sheared fibres start to rotate and align parallel to the streamlines (Barbosa et al 1994). Thus, with increasing shear deformation the fibre angle distribution is expected to shift from a flat curve without distinctive maximum to a curve with a maximum at small angles.…”

“…Theories of fibre suspension rheology were recently reviewed by Petrie (1999). The description of fibre orientation in flow is the main objective of experimental studies carried out with concentrated fibre suspensions (Stover et al 1999;Barbosa et al 1994). Experimental work treating the effect of fibre orientation on the rheology can also be found (Ganani and Powell 1985;Petrich et al 2000).…”

Carbon Nanotube/Nanofibre Polymer Composites

“…The combination of high shear and elongational flows, occurring during processing under non-isothermal conditions, leads to complex variations in molecular orientation and crystal morphology. Furthermore, there is a direct influence of reinforcing fibres on the surrounding matrix which depends on the interfacial interactions, the fibre volume fraction, as well as the aspect ratio and orientation of the fibres [196,197]. Finally, relative movements between filler and matrix during processing result in a modification of the local flow field and molecular conformation.…”