An application of the step-shear-rate method to pseudoplastic flow of styrene-acrylamide copolymer particles/ n-alcohol suspensions

• Published in: Journal of colloid and interface science 1986-12, Vol.114 (2), p.505-512
• Main Authors: Ishihara, Tadashi, Kurose, Takako, Kuno, Hiroshi
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Rheology and viscoelasticity
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/0021-9797(86)90436-4

The pseudoplastic flow of suspensions of styrene-acrylamide copolymer particles in n-alcohols has been studied by applying the step-shear-rate method. A constant dispersed state of the suspension was assumed during the step-shear-rate measurements. The relation between the shear stress r and the shear rate D using this method was expressed by τ = AD 1 2 + CD where A and C are constants. The effective volume fraction φ F of the suspension was calculated by applying modified Krieger's equation to C C = η 0(1 − φ F 0.74 ) −1.85 where η 0 is the viscosity of the medium. The effect of changes in steady dispersed state with shear rate on the steady flow behavior was studied by changing the starting shear rate of step-shear-rate measurement. A and φ F were proportional to D β and D b , respectively. The relation between shear stress and shear rate in steady pseudoplastic flows was expressed by τ = αD β+ 1 2 + η 0(1 − aD b 0.74 ) −1.85 D where a, b, α, and β are constants, whose changes with solid concentration, temperature, and type of medium were also examined.