Abstract
This work studies the influence of the concentration and oxidation degree on the rheological behavior of graphene oxide (GO) nanosheets dispersed on polyethylene glycol (PEG). The rheological characterization was fulfilled in shear flow through rotational rheometry measurements, in steady, transient and oscillatory regimes. Graphene oxide was prepared by chemical exfoliation of graphite using the modified Hummers method. The morphological and structural characteristics originating from the synthesis were analyzed by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and atomic force microscopy. It is shown that higher oxidation times increase the functional groups, which leads to a higher dispersion and exfoliation of GO sheets in the PEG. Moreover, the addition of GO in a PEG solution results in significant growth of the suspension viscosity, and a change of the fluid behavior from Newtonian to pseudoplastic. This effect is related to the concentration and oxidation level of the obtained GO particles. The results obtained aim to contribute towards the understanding of the interactions between the GO and the polymeric liquid matrix, and their influence on the suspension rheological behavior.
Highlights
Graphene was first obtained and characterized in 2004 by two Russian researchers that used the mechanical exfoliation technique to peel a graphite plate and obtain fine graphene flakes [1]
This work presented a rheological characterization of suspensions of graphene oxide (GO)
GO characterization techniques showed that the oxidation and that nanosheets in polyethylene glycol (PEG)
Summary
Graphene was first obtained and characterized in 2004 by two Russian researchers that used the mechanical exfoliation technique to peel a graphite plate and obtain fine graphene flakes [1]. Due to its excellent electronic, mechanical, thermal, and optical properties, many studies about graphene have been developed, and its applicability has been increasing in several industrial sectors [7,8,9]. It has excellent properties and numerous applications, there are still some challenges to obtain large quantities of graphene with lower costs and higher structural quality (high purity). This fact has led to the necessity to study and analyze different processes of synthesis [10]
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