The multipass rheometer a review

Mackley, M. R.; Hassell, David

doi:10.1016/j.jnnfm.2011.01.007

Cited by 26 publications

(14 citation statements)

References 96 publications

(139 reference statements)

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“…Recently, a CCD camera was used to capture the local deformation along the specimen (105), whose results imply that the apparent extensional viscosity is meaningful only under geometric homogeneity. Moreover, the filament-stretching experiment can also be implemented in a multipass rheometer, which has an advantage of independently controlling both top and bottom pistons and fixing the midfilament position during the extension (106,107). Besides the standalone device to measure the extensional viscosity, such as RME and FSR, dual windup extensional rheometers with two kinds of geometry are developed recently.…”

Section: Rotational Rheometermentioning

confidence: 99%

Rheological Measurements

2013

Encyclopedia of Polymer Science and Technology

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Rheology is the science to study the flow and deformation of matter. It becomes an important field in material science and engineering, food, biotechnology, and so on. The objects in rheological study are not the ideal solid and ideal fluid, which can be described by the Hookean elastic model and the Newtonian viscous model, respectively. Instead, the rheological study often focuses on materials that can exhibit viscous, elastic, and plastic behavior under different flow conditions. They are often termed as complex fluids or soft matter, which include polymers, gels, suspensions, emulsions, biofluids, foods, inks (1). In contrast to hydrodynamics, which often accounts for the complex flow behavior of simple fluids, simple geometry is utilized in rheological measurements to understand the rather complicated relationship between the mechanical input and output of complex fluids. The real flow fields encountered in many applications (such as polymer extrusion, injection molding, blow molding, fiber spinning, inkjet printing, coating) are rather complicated (2). It becomes a problem whether the rheological measurements that performed under simple flow fields are useful in understanding the complicated flow behaviors of complex fluids. Fortunately, it has been proved in many examples that the properties determined from simple rheological measurements are sufficient to quantify the material parameters in various constitutive equations, which have been used widely and successfully to simulate the flow behaviors in polymer processing (3-11). The most frequently used simple flow fields are simple shear flow and simple extensional flow.The simplest geometry that defines the simple shear is two infinite parallel plates separated by a distance h. The liquid is set between two plates with one plate moving parallel to the other (Fig. 1). In reality, when the length L and the width B are much larger than the gap h, the flow in the center regime resembles the flow between two infinite plates. It means that the edge effects are ignored in most experimental shear geometries. In rheological measurements, the flow between two plates should be laminar. Moreover, it is usually assumed that the velocity across the gap satisfies a linear profile. As shown in Fig. 1, if the bottom plate is fixed and the upper plate moves horizontally with the velocity V, the fluid velocity varies linearly from 0 at the bottom plate to V at the upper plate if the no-slip boundary condition is satisfied. The linear velocity profile generates a constant velocity gradient, which is known as the shear rate. Then, the flow field between two parallel plates is homogeneous in the shear rate. The homogeneous assumption is nontrivial in the rheological tests since the actual velocity

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Section: Rotational Rheometermentioning

confidence: 99%

Rheological Measurements

2013

Encyclopedia of Polymer Science and Technology

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“…In this respect, methods based on flow birefringence could be considered as suitable candidates. For example, flow birefringence has gained significant popularity as a way for direct visualization and measurements of fluid stresses in complex geometries, where relatively simple optical devices similar to a polariscope are used. Despite the fact that the flow field is well understood for rotational rheometers, flow visualization in these instruments may be essential for observations of the stress field associated with possible phase transitions and morphological transformations enhanced by the flow, when application of the constitutive equations of fluid mechanics are not valid.…”

Section: Introductionmentioning

confidence: 99%

Applications of shear-induced polarized light imaging (SIPLI) technique for mechano-optical rheology of polymers and soft matter materials

Mykhaylyk

Warren

Parnell

et al. 2016

J. Polym. Sci. Part B: Polym. Phys.

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A new experimental method for studying the mechano-optical rheology of polymeric liquids and soft matter materials is presented. The method is based on a combination of rotational rheology and a recently developed optical technique-shear-induced polarized light imaging (SIPLI). The method provides a unique opportunity to monitor a complete sample view during rheological measurements in plate-plate and cone-and-plate geometry. Applications of the method are presented including simultaneous SIPLI and the rheology of the oriented lamellar phase of block copolymers and liquid crystals as well as a study of the thermally induced reversible transformation of worm-like micelles to spherical micelles. In addition, a direct relation between the shish formation and the polymer melt viscosity upturn during flow-induced crystallization of semi-crystalline polymers is demonstrated. An application of SIPLI for quantitative birefringence measurements is also shown.

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“…Both the pressure-driven slit flow apparatus constructed by Janeschitz-Kriegl et al 12 and improved by Kornfield et al,13 and the piston-driven slit rheometer developed by Mackley et al 23 and modified by Peters and coworkers, 24,25 can operate in the high stress region (of the order of 0.1 MPa) and are easily combined with time-resolved birefringence 24,26 and/or X-ray scattering [27][28][29][30] …”

Section: Introductionmentioning

confidence: 99%

High-Stress Shear-Induced Crystallization in Isotactic Polypropylene and Propylene/Ethylene Random Copolymers

Fernandez-Ballester

Cavallo

et al. 2013

Macromolecules

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IntroductionSemicrystalline polymers are usually processed from their molten state and subjected to intense shear and/or elongation flows. Such flow fields not only accelerate crystallization kinetics, which shortens the processing time, but can also change the morphology from isotropic spherulites to highly oriented shish-kebab structures 1-3 and, as a consequence, determine the ultimate product properties. Therefore, understanding the interplay between strong flow fields and the resulting structures is of importance for designing processing procedures to tailor these end product properties.Considerable work [4][5][6][7] has been devoted to this topic in the past half century. Many researchers have focused on the relation between shear flow and polymer crystallization, because shear fields are easily created with rotational 3 or sliding 8,9 plate-plate devices, on rotational rheometers, 10,11 and in pressure driven slit flows. 12,13 These test geometries are typically combined with time-resolved characterization techniques like mechanical spectrometry, 10, 11, 14 light scattering, 15,16 birefringence, 13, 17 X-ray scattering 7,18,19 and Fourier transform infrared (FTIR) spectroscopy, 9, 20, 21 etc. Significant progress has been made in understanding shear-induced crystallization, 4-7 while some of the fundamental issues remain unsolved. In particular, knowledge of basic mechanism of crystallization under high shear rates and stress-close to realistic processing conditions-is still limited. The need for such information is becoming urgent in order to improve the latest simulation models, since the results of numerical predictions of, for example, injection molding, 22 have to be validated and further refined from experimental evidence.Imposing a strong shear flow at chosen high shear rates or stresses under well-defined conditions requires a specially designed flow device. Both the pressure-driven slit flow apparatus constructed by Janeschitz-Kriegl et al. 12 and improved by Kornfield et al.,13 and the piston-driven slit rheometer developed by Mackley et al. 23 and modified by Peters and coworkers, 24,25 can operate in the high stress region (of the order of 0.1 MPa) and are easily combined with time-resolved birefringence 24,26 and/or X-ray scattering [27][28][29][30] AbstractCrystallization of an isotactic polypropylene (iPP) homopolymer and two propylene/ethylene random copolymers (RACO), induced by high-stress shear, was studied using in situ synchrotron wide-angle X-ray diffraction (WAXD) at 137 °C. The "depth sectioning" method (Fernandez-Ballester, Journal of Rheology 53:5 (2009), pp. 1229−1254) was applied in order to isolate the contributions of different layers in the stress gradient direction and to relate specific structural evolution to the corresponding local stress. This approach gives quantitative results in terms of the specific length of fibrillar nuclei as a function of the applied stress. As expected, crystallization becomes faster with increasing stress-from the inner to the outer layer-for...

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The multipass rheometer a review

Cited by 26 publications

References 96 publications

Rheological Measurements

Rheological Measurements

Applications of shear-induced polarized light imaging (SIPLI) technique for mechano-optical rheology of polymers and soft matter materials

High-Stress Shear-Induced Crystallization in Isotactic Polypropylene and Propylene/Ethylene Random Copolymers

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