Rheological Behavior of Poly(styrene-co-acrylonitrile)/Carbon Nanotubes Sponges for Fiber Electrospinning Applications

The influence of carbon nanotubes sponges (CNT–sponges) content at 0.1 wt.%, 0.3 wt.% and 0.5 wt.% on rheological properties of three series of polymeric solutions of poly (styrene-co-acrylonitrile) P(S:AN) was evaluated. For that, amplitude and frequency sweeps were made in order to determine the storage (G’) and loss (G’’) moduli, loss factor (tan δ), structural changes and homogeneity of polymeric composite solutions as function of polymeric content P(S:AN) 0:100, 20:80, 40:60 and 50:50 wt%:wt%. For polymeric composite solutions (PCS) of pristine polyacrylonitrile, the rheological measurements show a Newtonian behavior at low shear rates and non-Newtonian behavior at higher values, meanwhile, all copolymeric PCS perform a non-Newtonian (shear thinning) behavior with a viscosity range of 0.8 < η /Pa·s < 20. The loss factor indicates a liquid-like behavior for solutions with 0.1 wt.% and 0.3 wt.% of CNT–sponges content, meanwhile a solid-like behavior was observed for 0.5 wt.% concentration. Finally, the polymeric composite solutions were processed in an electrospinning system to obtain fibers and were analyzed by SEM technique, CNT-sponges agglomerations were found into fibers with 0.5 wt.% content. The aim of this rheological analysis was carried out to predict the viscoelastic parameters and the suitability of solutions to electrospun process.