کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
607743 1454601 2013 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Migration and alignment of spherical particles in sheared viscoelastic suspensions. A quantitative determination of the flow-induced self-assembly kinetics
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی شیمی کلوئیدی و سطحی
پیش نمایش صفحه اول مقاله
Migration and alignment of spherical particles in sheared viscoelastic suspensions. A quantitative determination of the flow-induced self-assembly kinetics
چکیده انگلیسی

Flow-Induced Self-Assembly (FISA) is the flow-driven formation of ordered structures in complex fluids. In this paper the effect of shear flow on the microstructure formation of dilute sphere suspensions in a viscoelastic fluid has been studied experimentally by optical microscopy techniques. The system is formed by Polymethylmethacrylate beads suspended in 20 wt.% aqueous solutions of Hydroxypropylcellulose at volume fractions ranging between 0.1% and 1.0%. Experiments show that, under the action of flow, beads migrate from the bulk to the shear walls, there forming strings aligned along the flow direction. Strings grow with time eventually reaching a steady-state final length. The alignment kinetics have been quantified by means of an alignment factor, which is a measure of the average length of the strings. The experimental results indicate that both shear rate and particle concentration are relevant factors in determining the alignment factor kinetics. In particular, it is shown that, upon increasing shear rate, strings grow both faster and longer. As a consequence, the characteristic time of the overall alignment process remains roughly constant. It is also shown that an increase in particle volume fraction determines effects similar to an increase of shear rate.

Figure optionsDownload high-quality image (79 K)Download as PowerPoint slideHighlights
► Self- assembly of spheres in a viscoelastic fluid was obtained under shear flow.
► Beads migrate from the bulk to the shear cell walls, where they form strings.
► The alignment kinetics have been quantified via optical methods.
► A suitable alignment factor has been defined.
► Upon increasing shear rate and bead concentration, strings grow faster and longer.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Colloid and Interface Science - Volume 394, 15 March 2013, Pages 49–54
نویسندگان
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