Filling the gap between transient and steady shear rheology of aqueous graphene oxide dispersions
- 316 Downloads
Even though the rheological behavior of aqueous graphene oxide (G-O) dispersions has been shown to be strongly time-dependent, only few transient measurements have been reported in the literature. In this work, we attempt to fill the gap between transient and steady shear rheological characterizations of aqueous G-O dispersions in the concentration range of 0.004 < ϕ < 3.5 wt%, by conducting comprehensive rheological measurements, including oscillatory shear flow, transient shear flow, and steady shear flow. Steady shear measurements have been performed after the evaluation of transient properties of the G-O dispersions, to assure steady-state conditions. We identify the critical concentration ϕ c = 0.08 wt% (where G-O sheets start to interact) from oscillatory shear experiments. We find that the rheology of G-O dispersions strongly depends on the G-O concentration ϕ. Transient measurements of shear viscosity and first normal stress difference suggest that G-O dispersions behave like nematic polymeric liquid crystals at ϕ/ϕ c = 25, in agreement with other work reported in the literature. G-O dispersions also display a transition from negative to positive values of the first normal stress difference with increasing shear rates. Experimental findings of aqueous graphene oxide dispersions are compared and discussed with models and experiments reported for nematic polymeric liquid crystals, laponite, and organoclay dispersions.
KeywordsGraphene oxide Liquid crystals 2D suspensions 2D dispersions Normal stress Rheology
The authors thank Dr. Steven Aird for careful proof reading. The authors also thank Prof. Pier Luca Maffettone, Prof. Giovanniantonio Natale, and Prof. Gareth McKinley for helpful discussions. F.D.G. and A.Q.S. gratefully acknowledge the support of the Okinawa Institute of Science and Technology Graduate University with subsidy funding from the Cabinet Office, Government of Japan. B.V.C. and R.S.R were supported by IBS-R019-D1.
- Akbari A, Sheath P, Martin S T, Shinde D B, Shaibani M, Banerjee P C, Tkacz R, Bhattacharyya D, Majumder M (2016) Large-area graphene-based nanofiltration membranes by shear alignment of discotic nematic liquid crystals of graphene oxide. Nat Commun, 7Google Scholar
- Barnes HA, Hutton JF, Walters K (1989) An introduction to rheology, vol 3. Elsevier, AmsterdamGoogle Scholar
- Ewoldt RH, Johnston MT, Caretta LM (2015) Experimental challenges of shear rheology: how to avoid bad data. In: Complex fluids in biological systems. Springer, pp 207–241Google Scholar
- Kiss G, Porter R S (1978) Rheology of concentrated solutions of poly (γ-benzyl-glutamate). In: Journal of polymer science: polymer symposia, Wiley Online Library, vol 65, pp 193–211Google Scholar
- Larson RG (1999) The structure and rheology of complex fluids, vol 150. Oxford University Press, New YorkGoogle Scholar
- Macosko C (1994) Rheology: Principles, measurements, and applications. 1994. Wiley-VCH, WeinheimGoogle Scholar
- Marrucci G, Maffettone P (1990a) Nematic phase of rodlike polymers. I. Prediction of transient behavior at high shear rates. J Rheol 34(8):1217–1230Google Scholar
- Marrucci G, Maffettone P (1990b) Nematic phase of rodlike polymers. II. Polydomain predictions in the tumbling regime. J Rheol 34(8):1231–1244Google Scholar
- Pignon F, Magnin A, Piau J M (1997a) Butterfly light scattering pattern and rheology of a sheared thixotropic clay gel. Phys Rev Lett 79(23):4689Google Scholar
- Pignon F, Magnin A, Piau J M, Cabane B, Lindner P, Diat O (1997b) Yield stress thixotropic clay suspension: investigations of structure by light, neutron, and x-ray scattering. Phys Rev E 56(3): 3281Google Scholar
- Walters K (1975) Rheometry. Chapman & Hall, LondonGoogle Scholar