Effect of γ-Fe2O3 nanoparticles on rheological and volumetric properties of solutions containing polyethylene glycol

The effect of γ-Fe 2 O 3 nanoparticles on the rheological and volumetric properties of polyethylene glycol with molar mass of 400 (g mol −1 ), PEG400, and the dilute solutions of PEG400-PEG2000 and PEG400-PEG6000 was investigated. PEGs with molar masses of 2000 and 6000 (g mol −1 ) were dissolved in PEG400 to prepare the homogeneous solutions. Rheological properties and the density values for these solutions were measured. Nanoparticles of γ-Fe 2 O 3 were added to these solutions and dispersed by an ultrasonic bath for making the homogeneous nanofluids. The UV–Vis spectroscopy, zeta potential and dynamic light scattering have been used to specify the stability and particle size distribution of colloidal solutions studied. Fluid flow and suspense structure of γ-Fe 2 O 3 nanoparticles in the base fluids of PEG400, PEG400-PEG2000 and PEG400-PEG6000 were studied by measuring the magnetorheological properties at T = 298.15 K. Bingham plastic, Herschel–Bulkley, and Carreau–Yasuda models have been applied for modeling the magnetorheological properties of nanofluids. Interparticle interactions that occurred in the investigated nanofluids can be determined by calculating the excess molar volume values. This requires to measure the density data for γ-Fe 2 O 3 -PEG400, γ-Fe 2 O 3 -PEG400-PEG2000 and γ-Fe 2 O 3 -PEG400-PEG6000 systems at T = (298.15, 308.15 and 318.15) K. The excess molar volumes were calculated from these data and fitted with Ott et al. and Singh et al. equations.