title: Spreading of completely wetting, non-Newtonian fluids with non-power-law rheology.
abstract: Spreading non-Newtonian liquids with non-power-law rheology on completely wetting surfaces are seldom investigated. This study assessed the wetting behavior of polydimethylsiloxane (PDMS), a Newtonian fluid, two carboxymethylcellulose (CMC) sodium solutions, a PDMS+2%w/w silica nanoparticle suspension and three polyethylene glycol (PEG400)+5-10%w/w silica nanoparticle suspensions (non-power-law fluids) on a mica surface. The theta(D)-U and R-t data for spreading drops of the six tested, non-power-law fluids can be described by power-law wetting models. We propose that this behavior is attributable to a uniform shear rate (a few tens to a few hundreds of s(-1)) distributed over the thin-film regime that controls spreading dynamics. Estimated film thickness was below the resolution of an optical microscope for direct observation. Approximating a general non-Newtonian fluid spreading as a power-law fluid greatly simplifies theoretical analysis and data interpretation.
authors.affiliation: Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Min
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Duan
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Wang
authors.forename: Zhan-Peng
authors.initials: ZP
authors.lastname: Liang
authors.forename: Duu-Jong
authors.initials: DJ
authors.lastname: Lee
authors.forename: Ay
authors.initials: A
authors.lastname: Su