Orthogonal superposition rheometry of colloidal gels: time-shear rate superposition. Issue 42 (17th October 2018)

• Record Type: Journal Article
• Authors: Sung, Sang Hoon; Kim, Sunhyung; Hendricks, Jan; Clasen, Christian; Ahn, Kyung Hyun
• Is Part Of: Soft matter. Volume 14:Issue 42(2018)
• Page Start: 8651
• Page End: 8659
• Publication Date: 2018-10-17
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c8sm01512k
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : Shear rate tunes a master clock for all relaxation modes in the sheared colloidal gels to produce a "time-shear rate superposition (TSS)". Abstract : We explore the relaxation behavior of model colloidal gels under steady shear flow by means of orthogonal superposition rheometry. Fumed silica and carbon black dispersions in Newtonian matrices are used as a model system. As shear rate increases, the frequency dependent orthogonal moduli of the gels shift along the frequency axis without changing their shape, which finally can be superimposed to yield a single master curve. This indicates that the shear rate tunes a master clock for overall relaxation modes in the sheared colloidal gels to produce a "time-shear rate superposition (TSS)", as temperature does in polymeric liquids to produce a time-temperature superposition (TTS). The horizontal shift factor required at each shear rate to obtain the master curve is found to be directly proportional to the suspension viscosity for all the cases. From this result, we suggest that the suspension viscosity determines the overall relaxation time of the particles in the flowing colloidal gel.