Viscosity of polystyrene solutions expanded with carbon dioxide

Abstract

ABSTRACT:The viscosity of solutions of polystyrene (PS) in decahydronaphthalene (DHN) was measured in the presence of carbon dioxide (CO 2 ) with a moving-piston viscometer. The effects of the CO 2 pressure (0 -21 MPa), polymer concentration (1-15 wt %), temperature (306 -423 K), and polymer molecular weight (126 and 412 kDa) on the viscosity were investigated. In the absence of CO 2 , the increase in the viscosity with increasing polymer concentration was approximately exponential in concentration and was well described by the Martin equation. All the data fell on a single line when the relative viscosity was plotted against cM 0.50 (where c is the concentration of the polymer in solution and M is the molecular weight of the polymer). The viscosity of the polymer solution decreased with increasing CO 2 pressure under otherwise constant conditions. For a given CO 2 pressure, the viscosity reduction was greatest when the relative viscosity was high in the absence of CO 2 , that is, for high-molecular-weight polymer, high polymer concentrations, and low temperatures. Reductions in the relative viscosity of almost 2 orders of magnitude were observed in some cases. The viscosity of solutions of PS in DHN also was measured in the presence of sulfur hexafluoride (SF 6 ). At a given pressure, SF 6 was about as effective as CO 2 in reducing the solution viscosity.

The influence of charge ratio on transient networks of polyelectrolyte complex micelles

“…An exponential increase of the viscosity has been reported in rheological experiments on other soft colloidal systems such as emulsions 58 and polymer solutions. 59,60 It has also been predicted by Semenov et al, who showed that the relaxation time, and thus the viscosity, of a transient network of triblock copolymers should increase exponentially with concentration, in a concentration regime just above the overlap concentration. 61 This may well be the concentration regime we are investigating here.…”

Gas-Expanded Liquids

“…Other reported rheological measurements of CO 2 + polymer melts include poly(butylene succinate) (PBS), poly(dimethylsiloxane) (PDMS), low-density polyethylene, poly(ethylene glycol) (PEG), PMMA, polypropylene (PP), , polystyrene, , and poly(vinylidene fluoride) (PVDF) . Whittier et al report a 2 orders of magnitude reduction in the relative viscosity of PS in decahydronaphthalene in the presence of either CO 2 or SF 6 . Sarrade et al report a 5- to 500-fold reduction in the viscosities of spent oils and polymers swollen with dense CO 2 .…”

Transport Phenomena in Catalytic Hydrocracking of Polystyrene in Solution

“…Viscosity of PS/DHN solutions has been estimated according to Gandhi–Williams equation as a function of DHN viscosity, which has proven to be valid in a wide range of temperatures. , Viscosity of DHN solvent has been estimated with the free-volume viscosity model developed by Allal et al and the parameters given by Cain et al Estimated values of viscosity of PS/DHN mixtures at different pressures, temperatures, PS concentrations, and PS average molecular weights have been also included in Table .…”