Shear and elongational rheometry for determination of spinnability window of polymer solutions in solution blow spinning
Michał Wojasiński, Tomasz Ciach
Abstract
Abstract Recently, processes for stable and efficient production of polymeric nano‐ and submicron fibrous materials, like solution blow spinning, have developed rapidly. However, the application of new polymers, synthetic or natural, for the fabrication of innovative fibrous materials still requires a trial‐and‐error approach to determine the spinnability window of polymer concentration in the solution. In this study, we investigated the use of shear and elongational rheometry to determine the spinnability window of polymer solutions of two synthetic polymers—poly‐L‐lactic acid (PLLA) and polyurethane (PU). Based on measured values of four polymer solution properties: density, surface tension, zero shear viscosity, and relaxation time, we calculated Ohnesorge (Oh) and Deborah (De) numbers corresponding to the polymer concentration ranges from 1 to 9%w/w for PLLA and 1–12%w/w for PU. After blow spinning each of the investigated solutions and using images from the scanning electron microscope and calculated values of Oh and De numbers, we determined the spinnability window for both polymers in the solution blow spinning process to be Oh >0.5, De/Oh >1, and Oh < 25.