Topic
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 article, the phenomenon of flow-induced crystallization was investigated using a linear polyethylene above its normal melting point flowing continuously in a Biconical Rheometer, and it was found that the resin crystallized in the superheated state at rates which increased with increasing shear rate and decreasing temperature.
Abstract: The phenomenon of flow-induced crystallization was investigated using a linear polyethylene above its normal melting point flowing continuously in a Biconical Rheometer. It was found that the resin crystallized in the superheated state at rates which increased with increasing shear rate and decreasing temperature. A method of analysis of the temperature dependence of the various stages of flow induced crystallization is proposed. It deals with and attempts to explain the experimental fact that a higher viscosity enhances the rate of flow-induced crystallization in contrast to the effect of viscosity on the rate of quiescent crystallization. Some of the flow-induced crystallization samples were transparent and exhibited a high DSC thermogram “tail”.
40 citations
TL;DR: In this paper, a modified thixotropy/migration model was proposed to characterize the stress decay process of mortars under constant shear flow with the aid of a modified three-dimensional model, and the effect of sand volume fraction, clay addition and applied shear rate on the kinetics and intensity of colloidal deflocculation and sand migration.
40 citations
TL;DR: The shear rate dependence of the viscosity showed shear thinning behavior, which implies that some structure should exist in the liquid and the structure should change at high shear rates.
Abstract: The effect of adding an inorganic salt, lithium chloride, and water on the viscosity of an ionic liquid, 1-n-butyl-3-methylimidazolium chloride (BmimCl), was investigated by shear stress measurements with a rheometer. The shear rate dependence of the viscosity showed shear thinning behavior, which implies that some structure should exist in the liquid and the structure should change at high shear rates. Addition of LiCl enhances the viscosity of BmimCl. The logarithmic value of zero-shear viscosity, eta(0), of BmimCl increases linearly and largely with increasing added salt content. The increasing rate of the viscosity by addition of LiCl was about 10 times larger than that for an aqueous solution of LiCl. When water is added into BmimCl, viscosity decreased. The increasing rate of the viscosity by addition of LiCl for BmimCl with about 5 wt % of water was almost the same as that for BmimCl without addition of water.
40 citations
TL;DR: In this article, a polypropylene/ammonium polyphosphate/polyurethane intumescent fire retardant material was measured using a plate-plate rheometer.
Abstract: This work studies a polypropylene/ammonium polyphosphate/polyurethane intumescent fire retardant material. It reports the foaming expansion under a normal strain and the variation of the apparent viscosity of the heat-treated material measured using a plate–plate rheometer. The loss of the protective character of the intumescent coating is discussed. It is proposed that it is related to a limited foaming expansion value, an increase of its apparent initial viscosity and a decrease of this viscosity with time when a normal force and a sinusoidal strain are both applied. The changes in the dynamic properties of the system are explained by the chemistry of the intumescence process. Copyright © 1999 John Wiley & Sons, Ltd.
40 citations
TL;DR: In this paper, the rheological properties of poly α-olefins in Varsol 80 were studied using laminar and Taylor flows using a commercial rheometer equipped with a double-gap sample holder with axial symmetry.
Abstract: The rheological properties of 1–50 ppm poly α-olefins in Varsol 80 were studied using laminar and Taylor flows. In Taylor flow, all the studied poly α-olefins displayed polymer induced drag reduction and polymer scission. The measurements were carried out using a commercial rheometer equipped with a standard double-gap sample holder with axial symmetry. We find that this particular instrument even at the maximum obtainable geometrically averaged shear rate of 15,000 s −1 yields, an accuracy and a reproducibility better than ±2.5%. This unique precision for measurements in the presence of Taylor vortices, the small amounts of sample and time needed to carry out the measurements, and the general availability of the rheometer, suggests that these previously unexplored properties of this instrument will be of significant value for future investigations of polymer induced drag reduction.
40 citations