Viscoelastic material functions of noncolloidal suspensions with spherical particles
作者:
Birnur K. Aral,
Dilhan M. Kalyon,
期刊:
Journal of Rheology
(AIP Available online 1997)
卷期:
Volume 41,
issue 3
页码: 599-620
ISSN:0148-6055
年代: 1997
DOI:10.1122/1.550841
出版商: The Society of Rheology
关键词: Suspension;Normal stress, negative
数据来源: AIP
摘要:
We have characterized various steady and time-dependent material functions of suspensions of a non-Newtonian binder, poly(dimethyl siloxane), incorporated with 10%–60% by volume of hollow and spherical glass beads. The material functions included storage and the loss moduli, shear stress and first normal stress difference growth and relaxation, relaxation modulus upon step strain and creep and recovery behavior. Both constant shear stress and shear rate experiments were carried out using multiple rheometers over a broad temperature range (−35to 40 °C) while following sample fracture and wall slip effects. With increasing volume fraction, φ, of the noncolloidal particles, the strain range, over which linear viscoelastic behavior is observed, became narrower and the relaxation time of the suspension increased. Increasing solid content gave rise to the development of the yield stress and the dependence of large amplitude oscillatory shear properties on time and deformation history. The yield stress values increased with φ, but were not sensitive to temperature. Forφ⩾0.3the first normal stress difference values reached reproducible and steady negative values (with tensile force positive). Larger negative values of the first normal stress difference were observed with increasing deformation rate and solid concentration. The manifestations of the material functions resulting from the incorporation of the solids into the non-Newtonian binder included the suppression of the extrudate swell and the dipping of the free surface in the Weissenberg experiment.
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