Shear thickening implies that the viscosity of a fluid increases with increasing rates of shear. In the past work reported, all shear thickening phenomena were observed in concentrated solid/liquid colloidal suspensio...Shear thickening implies that the viscosity of a fluid increases with increasing rates of shear. In the past work reported, all shear thickening phenomena were observed in concentrated solid/liquid colloidal suspension. In this paper, the shear thickening was observed in colloidal dispersion gel, with very lower volume fraction, of partially hydrolyzed polyacrylamide(PHPA)/aluminum citrate. Colloidal dispersion gels are made of low concentrations of polymer and crosslinker. Polymer mass fractions normally range from 0.01% to 0.12%. In this concentration regime, there is not enough polymer to form a continuous network, so a conventional bulk type gel cannot form. Instead of a solution of separate gel bundles forms, and it is a mixture of predominantly intramolecular and minimal intermolecular crosslinks. In the work reported here, the colloidal dispersion gels are made of PHPA of 0 03%, KCl of 0.5%, thiourea of 0.1% and Al 3+ with a mass fractions range of 0—0 003%, the Al 3+ ∶PHPA mass ratio changes from 0 to 0.1. The critical shear rates(CSR) for the onset of shear thickening are about 200 s -1 for all CDG systems studied, i.e ., the Al 3+ ∶PHPA mass ratio don’t affect the CSR. In the lower shear regime than CSR shear thinning was observed and in the higher shear regime than CSR the shear thickening was observed. The shear thickening may be explained with cluster formation mechanism.展开更多
The secondary structure parameters of partially hydrolyzed poly(acrylamide)(HPAM) in the process of chemical oil recovery have been determined by means of GPC-light scattering cooperation. It was found that the mean m...The secondary structure parameters of partially hydrolyzed poly(acrylamide)(HPAM) in the process of chemical oil recovery have been determined by means of GPC-light scattering cooperation. It was found that the mean molecular mass of HPAM had decreased to 4 to 8 times, the molecular mass distribution of HPAM became broad. It has been deduced that the molecular mass decrease of HPAM results from the HPAM degradation and the mechanical degradation is a determinant because the molecular mass distributions of HPAM after degradation were narrower than the results estimated with the random degradation theory. The chain flexibility somewhat decreased when HPAM solution flowed in underground sandstones in the period of 6 to 8 months, that is, (<S 2> n/<M> n) 1/2 increased from original 0.065 to 0.075 for HPAM in flooding 2 and 4 years and 0.081 for 6 years, which maybe imply HPMA further hydrolyzed under the underground weak basic condition of the oilfield.展开更多
文摘Shear thickening implies that the viscosity of a fluid increases with increasing rates of shear. In the past work reported, all shear thickening phenomena were observed in concentrated solid/liquid colloidal suspension. In this paper, the shear thickening was observed in colloidal dispersion gel, with very lower volume fraction, of partially hydrolyzed polyacrylamide(PHPA)/aluminum citrate. Colloidal dispersion gels are made of low concentrations of polymer and crosslinker. Polymer mass fractions normally range from 0.01% to 0.12%. In this concentration regime, there is not enough polymer to form a continuous network, so a conventional bulk type gel cannot form. Instead of a solution of separate gel bundles forms, and it is a mixture of predominantly intramolecular and minimal intermolecular crosslinks. In the work reported here, the colloidal dispersion gels are made of PHPA of 0 03%, KCl of 0.5%, thiourea of 0.1% and Al 3+ with a mass fractions range of 0—0 003%, the Al 3+ ∶PHPA mass ratio changes from 0 to 0.1. The critical shear rates(CSR) for the onset of shear thickening are about 200 s -1 for all CDG systems studied, i.e ., the Al 3+ ∶PHPA mass ratio don’t affect the CSR. In the lower shear regime than CSR shear thinning was observed and in the higher shear regime than CSR the shear thickening was observed. The shear thickening may be explained with cluster formation mechanism.
文摘The secondary structure parameters of partially hydrolyzed poly(acrylamide)(HPAM) in the process of chemical oil recovery have been determined by means of GPC-light scattering cooperation. It was found that the mean molecular mass of HPAM had decreased to 4 to 8 times, the molecular mass distribution of HPAM became broad. It has been deduced that the molecular mass decrease of HPAM results from the HPAM degradation and the mechanical degradation is a determinant because the molecular mass distributions of HPAM after degradation were narrower than the results estimated with the random degradation theory. The chain flexibility somewhat decreased when HPAM solution flowed in underground sandstones in the period of 6 to 8 months, that is, (<S 2> n/<M> n) 1/2 increased from original 0.065 to 0.075 for HPAM in flooding 2 and 4 years and 0.081 for 6 years, which maybe imply HPMA further hydrolyzed under the underground weak basic condition of the oilfield.
