Two‐dimensional modeling of polymer wet spinning: The effects of mass transfer dynamics on structural properties

Abstract

In this work, a two-dimensional model of polymer wet spinning that couples simultaneous momentum and energy transport with ternary diffusion and phase separation processes is presented and its predictions for a model system are discussed. The uniqueness of the model lies in its two-phase nature and ability to predict important characteristics of the wet spinning process, such as the locking-in of axial velocity, mass transfer behavior, and internal structure formation along the spinline. The model predicts growth of the two-phase gel that forms and the porous fractions within it, along with the compositions of the polymer-rich and solvent-nonsolvent-rich phases. The appearance of a skin-core structure that depends on the system and operating conditions is also predicted. These features are demonstrated through analyses of the isothermal wet spinning of poly(acrylonitrile) solutions in dimethlysulfoxide using two different nonsolvent coagulants, water and ethanol.

Stretchable, conductive and porous MXene-based multilevel structured fibers for sensitive strain sensing and gas sensing

“…Such porosity distribution may be attributed to the phase separation distribution across the radial direction. 39 Similar porous structures have been observed in wet-spun polymer fibers such as PAN, 40,41 PVDF, 42 and poly(lactide- co -glycolide). 43 However, to the best of our knowledge, this is the first time that fibers with both good stretchability and conductivity have been produced using this phase separation mechanism.…”

Reaction-Spun Transparent Silica Aerogel Fibers

“…The spinnability is determined by the diffusivity and gelation speed of the resulting CS. − As for the CS 1.2–0.01 , it contains soluble oligomers. To obtain a gel network, these oligomers first need more water to hydrolyze to form a colloid (sol) and then further condense to form a gel; that is why more than 30 min is needed for CS 1.2–0.01 to form a gel according to Fick’s law, J = –D∇ϕ , where J is the diffusion flux, D the diffusion coefficient or diffusivity, and ϕ the concentration.…”

An efficient numerical framework for fiber spinning scenarios with evaporation effects in airflows

“…The works of [12,13] extended the models by incorporating viscoelastic material laws. Apart from that, the effect of solvent evaporation was taken into account in mathematical models for several other spinning processes like melt spinning [15,34] and electrospinning [33,32].…”