Rheological Measurements

Schöff, Clifford K.; Kamarchik, Peter

doi:10.1002/0471440264.pst521

Cited by 6 publications

(8 citation statements)

References 302 publications

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“…The Ostwald‐de Waele law, or the “power‐law”,18 is widely used for non‐Newtonian fluids, where τ is shear stress (Pa), is shear rate(s −1 ), K is a viscosity related constant, and n (flow behavior index) is an exponent that equals the slope of the logτ −log flow curve. For Newtonian fluids, n = 1; for dilatant fluids, n > 1; for pseudoplastic fluids, n < 1.…”

Section: Resultsmentioning

confidence: 99%

Rheological behavior of semi‐aromatic transparent polyamide

Chen

et al. 2005

J of Applied Polymer Sci

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ABSTRACT:The rheological behaviors of semi-aromatic transparent polyamide (SATPA) melt are investigated using a capillary rheometer. The effects of shear rate, shear stress, and temperature on the apparent viscosity a of SATPA are discussed. A correlation of non-Newtonian index with temperature is obtained. The results show the shear thinning of SATPA; meanwhile a decreases with increasing temperature and shear rate, and the viscous flow activation energy is further obtained from temperature dependence of the samples. It was concluded that the apparent viscosity a is sensitive to temperature at lower shear rate owing to the higher viscous flow activation energy; on the contrary, the influence of temperature effect on the apparent viscosity becomes minor at higher shear rate due to the lower viscous flow activation energy.

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Section: Resultsmentioning

confidence: 99%

Rheological behavior of semi‐aromatic transparent polyamide

Chen

et al. 2005

J of Applied Polymer Sci

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“…The Ostwald‐de Waele or the “power‐law,”26 is widely used as a model for non‐Newtonian fluids, where τ is shear stress (Pa), is shear rate (s −1 ), K is a viscosity related constant, and n is an exponent (flow behavior index) that equals the slope of the log τ ‐log γ flow curve. For Newtonian fluids, n = 1; for dilatant fluids, n > 1; for pseudoplastic fluids, n < 1.…”

Section: Resultsmentioning

confidence: 99%

Study of rheological property of nylon‐1212 with Haake Rheometer

Zhang

Liu

Zhao

et al. 2003

J of Applied Polymer Sci

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Rheological properties of nylon-1212 have been studied by means of Haake Rheometer. The effect of shear rate and temperature on the apparent vicosity of nylon-1212 was discussed. A correlation of non-Newtonian index with the temperature was obtained. The results showed that the apparent viscosity decreases with the increase of the temperature. With increasing shear rate, shear thinning of nylon-1212 was observed clearly. From the relation of the temperature dependence of the polymer, we obtained the viscous flow activation energy. We conclude that the apparent viscosity is sensitive to temperature at lower shear stress because of higher viscous flow activation energy, and the temperature affect on the apparent viscosity becomes weaker at higher shear stress because of lower viscous flow activation energy. We have investigated the creep and elastic recovery of nylon-1212. A creep test was carried out to define the linear viscoelastic range as 1.0 and 5.0 Pa for 195 and 190°C nylon-1212 melts, respectively. A time-dependent response was found for the creep and recovery phases at a lower applied shear stress. However, at higher shear stress, the creep and recovery phases were time-independent.

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“…The rheology of paints depends mainly on the nature and concentration of the polymer matrix [1], and determines the performance of the paint during the whole handling cycle, from storage to application and drying [2]. The stability required on a paint to allow the storage of the dispersion without settling should be analyzed by dynamic rheology in the linear viscoelastic zone.…”

Section: Introductionmentioning

confidence: 99%

A simple model to describe the thixotropic behavior of paints

Armelín¹,

Martí²,

Rudé³

et al. 2006

Progress in Organic Coatings

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We propose a simple rheological model to describe the thixotropic behavior of paints, since the classical hysteresis area, which is usually used, is not enough to evaluate thixotropy. The model is based on the assumption that viscosity is a direct measure of the structural level of the paint. The model depends on two equations: the Cross-Carreau equation to describe the equilibrium viscosity and a second order kinetic equation to express the time dependence of viscosity. Two characteristic thixotropic times are differentiated: one for the net structure breakdown, which is defined as a power law function of shear rate, and an other for the net structure buildup, which is not dependent on the shear rate. The knowledge of both kinetic processes can be used to improve the quality and applicability of paints. Five representative commercial protective marine paints are tested. They are based on chlorinated rubber, acrylic, alkyd, vinyl, and epoxy resins. The temperature dependence of the rheological behavior is also studied with the temperature ranging from 5 ºC to 35 ºC. It is found that the paints exhibit both shear thinning and thixotropic behavior. The model fits satisfactorily the thixotropy of the studied paints. It is also able to predict the thixotropy dependence on temperature. Both viscosity and the degree of thixotropy increase as the temperature decreases.

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Rheological Measurements

Cited by 6 publications

References 302 publications

Rheological behavior of semi‐aromatic transparent polyamide

Rheological behavior of semi‐aromatic transparent polyamide

Study of rheological property of nylon‐1212 with Haake Rheometer

A simple model to describe the thixotropic behavior of paints

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