Rheological Behaviors of Polyacrylonitrile/1-Butyl-3- Methylimidazolium Chloride Concentrated Solutions

Weiwei Liu,Yumei Zhang,Lingyan Cheng,Mingfang Yu,Huaping Wang,Hongyan Zhang

doi:10.3390/i8030180

Weiwei Liu, Yumei Zhang + Show 4 more

Open Access

https://doi.org/10.3390/i8030180

Copy DOI

Abstract

One of the room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazoliumchloride ([BMIM]Cl) was chosen to prepare the concentrated solutions of Polyacrylonitrile(PAN). The rheological behaviors of the solutions were measured with rotational rheometryunder different conditions, including temperatures, concentration, and molecular weight ofPAN. The solutions exhibited shear-thinning behaviors, similar to that of PAN/DMFsolutions. The viscosities decreased with the increasing of shear rates. However, theviscosity decreased sharply at high shear rates when the concentration was up to 16wt%. Thedependence of the viscosity on temperature was analyzed through the determination of theapparent activation energy. Unusually, the viscosity of solutions of higher concentration islower than that of lower concentration. Similarly, the viscosity of low molecular weightPAN was higher than high molecular weight PAN at high shear rates. The dynamicrheological measurement indicates the loss modulus is much higher than storage modulus.The trend of complex viscosity is similar with the result of static rheological measurement.The interaction between PAN and ionic liquid [BMIM]Cl was discussed.

Highlights

Polyacrylonitrile (PAN) are commercially important and used for the precursor for highperformance carbon fiber
The apparent viscosity ηa is shown as a function of shear rate for the PAN in two different solvents, [BMIM]Cl and DMF
Within the limits of the experimental techniques accessible to us, the results obtained for PAN/[BMIM]Cl solutions show that they are pseudoplastic, similar to the PAN/traditional organic solvents solutions

Summary

Introduction

Polyacrylonitrile (PAN) are commercially important and used for the precursor for highperformance carbon fiber. PAN is dissolved in a suitable solvent and spin to. Several solvents have been used to prepare PAN spinning solutions. The ionic liquids have been studied since the 1950s [3], but they can not to be handled under an inert atmosphere These are not part of our studies until some kinds of water-stable and air-stable ionic liquids are found such as [BMIM]Cl. Because of its extremely low volatility, some of the RTILs are promising environment-friendly solvents instead of the volatile organic solvents in a range of science and technology applications such as media for organic and inorganic reactions [4,5], materials processing [6] electrochemistry [7] and chemical separation [8]. This paper investigates the rheological properties of PAN copolymer/BMIMCl concentrated solutions in some detail

Materials

Preparation of concentrated solutions

Rheometry

Results and discussion

Conclusions