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Correlation Of Polysiloxane Molecular Structure To Shear-Thinning Power-Law Exponent Using Elastohydrodynamic Film Thickness Measurements, Thomas Zolper, Paul Shiller, Gary Doll, Manfred Jungk, Tobin Marks, Yip Chung, Aaron Greco, Babak Dehkordi, Qian Wang

Gary L. Doll

Siloxane-based polymers (polysiloxanes) are susceptible to temporary shear-thinning that manifests as a reduction of elastohydrodynamic film thickness with increasing entrainment speed or effective shear rate. The departure from Newtonian film thickness can be predicted with the power-law exponent ns, an indicator of the severity of shear-thinning in a polymeric fluid that is influenced by the macromolecular structure. In this paper, a combination of extant rheological and tribological models is applied to determine the power-law exponent of several polysiloxanes using film thickness measurements. Film thickness data at several temperatures and slide-to-roll ratios are used to validate the methodology for several siloxane-based …