An experimental study of the relationship between rheological properties and spinnability in the dry spinning of cellulose acetate–acetone solutions

Abstract

SynopsisThe elastic and viscous properties of five cellulose acetateacetone solutions, varying from 19.9% to 28.6% solids concentration, are independently determined at 60°C by capillary rheometry techniques. The viscous flow behavior of the solutions is determined over four decades of shear rate. The Bagley analysis is used to determine the entrance pressure drop and the true shear stress at various shear rates. A plot of the entrance pressure drop at the maximum experimental shear rate versus solution concentration undergoes a rapid increase in slope at 24.0y0 solids concentration, the significance of which is discussed with respect to the development of an elastically deformable chain entanglement network. The die swell behavior of the solutions at 60°C is determined on a commercial-type dry-spinning apparatus. When the die swell ratio is plotted versus volumetric flow rate, all five solutions are found to possess a characteristic curve with a distinct maximum. Photographs illustrating the variation of die swell with volumetric flow rate are shown. Die swell measurements are also shown to correlate well with entrance pressure drop measurements. The degree of spinnability of each cellulose acetate-acetone solution at 60°C is found by determining first godet speed at which one or more threads break abruptly. Spinnability is found to go through a maximum at 24.0% solids concentration. The rheological measurements and spinnability results are discussed through the aid of a single rheological parameter incorporating both elastic and viscous solution responses.

Role of chain entanglements on fiber formation during electrospinning of polymer solutions: good solvent, non-specific polymer–polymer interaction limit

“…In theory, at even higher polymer concentrations (cOc*), increased chain entanglements can temporarily serve to stabilize the electrospinning jet by inhibiting jet breakup. For dry spinning it has been suggested that above a critical dope (polymer) concentration, the dynamic 'short range' network in the spinning solution is converted to a more stable elastically deformable 'long range' network as the solvent evaporates [34,35,47]. In other words, 'spinnable' solutions exhibit elastic properties [33].…”

A comparison of Newtonian and viscoelastic constitutive models for dry spinning of polymer fibers

“…It is believed by the authors that a similar entanglement network is also formed in the course of the dry spinning process. Leaving the spinneret, the spinning solution can be regarded as a “short range” entanglement network,17 which means the low entanglement frequency because of the considerable existence of solvent would allow viscous flow before solidification or significant elastic strain. After a critical solution concentration, which may correspond to the solidification point, the filament becomes a “long range” entanglement network, which implies that a given polymer chain in the network is entangled with other chains at a sufficient number of points along its length.…”

Drying Behavior of Acetate Filament in Dry Spinning

“…Concentration dependence of die swell ratio at 60 C(Griswold and Cuculo, 1974). Concentration dependence of die swell ratio at 60 C(Griswold and Cuculo, 1974).…”