Study of Extensional Rheology Behavior of Sodium Alginate/Polyethylene Oxide Solutions for Blow Spinning.

Blow spinning is a low-cost and versatile method that permits the large-scale production of fibrous membranes. However, polysaccharides that show numerous merits such as biocompatibility and biodegradability often have a low spinnability due to their high chain rigidity and low ability to form sufficient entanglements. Here, we report the fabrication of polysaccharide micro-fibrous membranes from sodium alginate/polyethylene oxide solutions formulated in solvent mixtures of water and ethanol. The shear and extensional rheological responses of the solutions are characterized, and parameters including specific shear viscosity, reptation time, extensional relaxation time, and maximum stretch ratio are correlated with the concentrations of polymer, polyethylene oxide, and ethanol. It is found that flexible polyethylene oxide and poorer solvent ethanol can synergistically delay the chain relaxation during stretch and increase the stretchability of the solutions. A processability map of the solutions for blow spinning is constructed, enabling the fabrication of fibrous membranes with a fiber diameter of ~1 μm, tensile strength of 4.89 MPa, elongation at break of 15.24%, and Young's modulus of 45.43 MPa. This study presents a new strategy to fabricate sodium alginate-based membranes, which should provide insights into the design of other polysaccharide membranes with specific functions and applications.