Influence of Oxidation Degree of Graphene Oxide on the Shear Rheology of Poly(ethylene glycol) Suspensions

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.

Tailoring the graphene oxide chemical structure and morphology as a key to polypropylene nanocomposite performance

“…Due to the hydrophilic feature of GO, [ 13 ] it presents higher chemical affinity with polar polymers. [ 17–21 ] Li et al [ 20 ] showed the influence of different oxidation degrees of GO on its structure and on the poly (vinyl alcohol)/graphene oxide (PVA/GO) composite properties. They observed that the higher the amount of oxidizing agent (KMnO 4 ) added to the synthesis of GO, the higher the oxidation degree of it.…”

Alignment of a flexible platelike particle in shear flow: Effect of surface slip and edges

“…Hereσ [i] represents the decreasing order values ofσ for which a stable aligned solution is found. For the first value,σ = σ [1], we use the stable solution of a rigid undeformed body oriented at φ c as the initial guess, and for the second, and slightly reduced, valueσ [2], we use the final profile from the previous step as the initial guess. For the following steps, the last two profiles forσ [i − 1] andσ [i − 2] are used to approximate an initial guess of the profile for the givenσ [i].…”

Rheology of Conductive High Reactivity Carbonaceous Material (HRCM)-Based Ink Suspensions: Dependence on Concentration and Temperature

“…In the particular case of 2D particle suspensions and molten composites, several works report either Newtonian or non-Newtonian flow behavior, thixotropicity, macroscale superlubricity, capability of forming particle network under shear flow, the presence of negative-to-positive normal stress first difference, and rheological responses similar to rod-like liquid crystal polymers as the main under-flow features [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Except for the work by Arapov and coworkers [ 22 ], the aforementioned studies have been carried out at a single temperature (room temperature in most cases) or within a small range of temperatures.…”