Experimental Analysis of the Extensional Flow of Very Weakly Viscoelastic Polymer Solutions.

Manuel Rubio,José María Montanero,Emilio José Vega,Alberto Ponce-Torres

doi:10.3390/ma13010192

Abstract

We study with ultra-high-speed imaging the thinning of the filament formed during the breakup of a pendant droplet of very weakly viscoelastic polymer solutions of polyvinylpyrrolidone (PVP) and polyethylene oxide (PEO). In the latter case, we consider two molecular weights: g/mol (PEO100K) and g/mol (PEO2M). The results allow us to measure with high reproducibility extensional relaxation times of the order of 10 s. Despite the noticeable differences between PVP and PEO100K, very similar values are obtained for the range of concentrations where the linear elasto-capillary is established. For PEO2M, the extensional relaxation time depends on the concentration even for values significantly smaller than the overlap one. The prediction for the concentration below which the linear elasto-capillary regime cannot be reached qualitatively agrees with the results for PVP and PEO2M, while it underestimates the critical concentration for PEO100K. The results for PEO2M are consistent with those reported in the literature for higher concentrations.

Highlights

Elastic polymer solutions have great relevance in many applications, such as inkjet printing and nanofiber spinning
We have presented an experimental technique for measuring extensional relaxation times of the order of 10 μs
The technique relies on the capillary thinning of the filament formed during the breakup of a pendant droplet hanging on a submillimeter feeding capillary

Summary

Introduction

Elastic polymer solutions have great relevance in many applications, such as inkjet printing and nanofiber spinning. Flexible electronic circuits are fabricated with droplet-based inkjet printing of PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)) [1] due to its high electrical conductivity, transparency, physical and chemical stability, and capability to form films. The production of nanofibers and their mats is useful for a wide range of applications, including filters, membranes, microelectronics, military, optics or health, and personal care, among many others [2]. Membranes and scaffolds made up of nanofibers of low-molecular-weight PVP (polyvinylpirrolidone) are widely used for tissue engineering due to its biocompatibility and low toxicity [3]. Experimental information about the extensional flow of polymer solutions with low molecular weights and low concentrations is very useful for the applications mentioned above and many others

Methods

Results

Conclusion