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Rheometer

About: Rheometer is a research topic. Over the lifetime, 5759 publications have been published within this topic receiving 125849 citations.


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TL;DR: In this paper, the authors describe the technical performance and initial results for a two-piston, "multipass rheometer" which is capable of extending the experimental ranges of many conventional rheometers, particularly in terms of pressure control, high shear rates, and multiple, successive flow measurements.
Abstract: This article describes the technical performance and initial results for a new, two‐piston, ‘‘multipass rheometer.’’ Fluid is contained within a capillary by two servo‐hydraulically controlled pistons. Both steady flow and oscillatory data can be obtained from the device with mean pressure as an independent adjustable variable. Steady and oscillatory data are presented for a silicone oil and a viscoelastic solution and certain data are compared with results obtained from a Rheometrics RDS‐II mechanical spectrometer or with literature data. The results show that the multipass rheometer is capable of extending the experimental ranges of many conventional rheometers, particularly in terms of pressure control, high shear rates, and multiple, successive flow measurements.

117 citations

Journal ArticleDOI
TL;DR: In this article, the authors characterized various steady and time-dependent material functions of suspensions of a non-Newtonian binder, poly(dimethyl siloxane), incorporated with 10% to 60% by volume of hollow and spherical glass beads.
Abstract: 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 (−35 to 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 i

116 citations

Journal ArticleDOI
TL;DR: A slit viscometer to measure the viscosity of polymer melts under processing conditions is described in this article, where a pressure drop is generated by applying a pressure at both the entrance and the exit.
Abstract: A slit viscometer to measure the viscosity of polymer melts under processing conditions is described. Along the slit a pressure drop is generated by applying a pressure at both the entrance and the exit. In this way the pressure in the center can be controlled independently of the shear rate. The pressure gradient in the slit is measured by means of three pressure transducers which are mounted in the region of fully developed flow. Results of pressure-dependent viscosity measurements on polystyrene, polyacrylonitrile-butadiene-styrene, and polypropylene are presented in a shear rate range of five decades. The flow curves obtained at different pressures and temperatures can be shifted onto a master curve. The shear thinning behavior of the three materials is adequately described with the generalized Cross-Carreau equation, while the zero shear viscosity is modeled with a generalized Arrhenius-W.L.F. relationship, incorporating a pressure dependency. Alternatively, it is possible to describe the zero shear viscosity in terms of the free volume fraction and the temperature.

116 citations

Journal ArticleDOI
TL;DR: In this article, the degradation of polypropylene (PP) during multiple extrusion at different temperatures was studied by following changes in rheological properties such as complex viscosity and elasticity of the molten polymer.

116 citations

Journal ArticleDOI
TL;DR: In this paper, a model for undiluted emulsions of Newtonian liquids has been used to account for the variations of dynamic moduli in the terminal zone of PP/PA6 blends.
Abstract: Linear viscoelastic dynamic moduli of two‐phase PP/PA6 blends in the molten state have been measured as a function of frequency in a cone and plate rheometer. With respect to the PP and PA6 components, blends are characterized by high values of the storage modulus at low frequencies and long relaxation times. A parallel has been drawn between these results and morphological observations of sheared specimens showing that the time required for deformed dispersed domains to revert to their spherical shape is of the same order of magnitude as mechanical relaxation times. A model for undiluted emulsions of Newtonian liquids has been used to account for the variations of dynamic moduli in the terminal zone. In this frequency range, the rheological behavior is directly related to a few physically significant parameters such as zero‐shear viscosity of phases, dispersed particle size, and surface tension between phases.

116 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023240
2022487
2021164
2020196
2019201
2018162