Evaporation and Rheology Chart the Processability Map for Centrifugal Force Spinning

Abstract

We show that poly(ethylene oxide) (PEO) solutions formulated using solvent mixtures of acetonitrile (AcN) and water can be centrifugally spun into fibers. We find that spinnability and fiber morphology depend on solvent choice if polymer concentration, solution shear rheology, the number of entanglements, extensional relaxation time, and the parameters for centrifugal spinning are nearly matched. We obtain an intrinsic spinnability map for volatile entangled (VE) polymer solutions by contrasting the measured shear relaxation time with the evaporation rate determined using thermogravimetric analysis (TGA). Finally, we chart a processability map for centrifugal spinning by plotting extensional relaxation time, measured for the volatile polymer solutions using a closed-cell dripping-onto-substrate (DoS) rheometry, against the time of flight (from the nozzle to the collector) by scaling both the timescales with an evaporation time. The processability map incorporates the influence of centrifugal spinning speed, nozzle diameter, distance from the collector, ambient conditions, and solvent and polymer properties, establishing an imitable paradigm for distinguishing between spinnable and sprayable formulations.