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Rheological Societies: Society's Site Mar 2012 - Aug 2012, Appl. Rheol. 22 (2012) 49.Sami Hietala
Nordic Rheology Conference 2011
Appl. Rheol. 22:1 (2012) 46-46 ►
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Hietala S: Nordic Rheology Conference 2011, Appl. Rheol. 22 (2012) 46.
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Cidade T, Sousa I, Franco JM: Iberian Meeting on Rheology - Rheology Trends: From Nano to Macro Systems (Ibero 2011): From nano to macro systems (Ibereo 2011), Appl. Rheol. 22 (2012) 44.
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Cheneler D: Colloidal Suspension Rheology (J. Mewis, N. J. Wagner), Appl. Rheol. 22 (2012) 12.
The measurement of elongational viscosity still evokes a series of problems in comparison with the relatively well-established measurement of shear viscosity. Recently new techniques have appeared enabling measurement of elongational viscosity with the samples for which the aspect ratios of their geometrical shapes (i.e. length vs. width (diameter)) can attain moderate values, i.e. not necessarily of a longitudinal character as in the case of earlier techniques. The aim of this contribution is to experimentally demonstrate the invariantness of transient uniaxial elongational viscosity measured with respect to a rectangular shape and thickness of LDPE samples using a SER Universal Testing Platform fixed in an Anton Paar MCR 501 host system. The width of the samples was varied within the range 2.1-12.7 mm and thickness altered within 0.1-1 mm. An advantage of fixing polymer samples directly to both drums (if possible) over the application of clamps is documented.► Cite this publication as follows:
Filip P, Svrcinova P: Measurement of elongational viscosity of polymer melts using SER Universal Testing Platform, Appl. Rheol. 22 (2012) 14776.
We applied the creep test that allows obtaining rheological information in the long-time domain (low-frequency range) that is not reachable by the use of the dynamic frequency sweep test to characterize the linear viscoelastic properties of polyethylene melts for industrial research and development. We considered the time scale for the creep test and what this imposes as limitations on the ability to make such measurements on a large group of samples. For the long- time creep test in the molten state at high temperatures, polyethylene demands very good stabilization with anti-oxidation packages to allow one to obtain useful data. The time for the sample relaxation from mounting and trimming in the parallel plate geometry of the controlled-stress rheometer prior to initiation of a creep test was also considered. The issue of what stress level to use in the linear viscoelastic region was addressed as was the issue of signal to noise. The creep test was performed within 4 hours for practical use, and the frequency range was extended down 10-4 rad/s. We tested several polyethylene samples as examples taking account of above variables and showed that the data obtained by the creep method overlapped well with low frequency end of the dynamic frequency sweep data. By testing several high molecular weight resins having broad molecular weight distribution and/or long chain branching, we demonstrated the utility of this methodology.► Cite this publication as follows:
Inn Y, Rohlfing DC: Application of Creep Test to Obtain the Linear Viscoelastic Properties at Low Frequency Range for Polyethylene Melts, Appl. Rheol. 22 (2012) 15260.
A high torque vane rheometer is used to measure the yields stress of cement-based materials. It is shown that this apparatus is suitable for the evaluation of the yield stress of various concretes and mortars in the fresh state in comparison with slump tests realized with ASTM Abrams cone. Then, the rheological properties (yield stress and shear flow behaviour) of a homogeneous kaolin clay suspension are studied with the apparatus and favourably compared with other rheometers and geometries.► Cite this publication as follows:
Estelle P, Lanos C: High torque vane rheometer for concrete: principle and validation from rheological measurements, Appl. Rheol. 22 (2012) 12881.
An effort is made to determine theoretically the new rheological properties of a rheologically defined non-Newtonian fluid as a result of the addition of particles in the original fluid. A theoretical model is proposed to determine the rheological properties of a dilute suspension of infinite-length round particles for a Power-Law fluid, which is treated as a homogeneous fluid with new rheological properties. The equations of a two-dimensional, dilatational, creeping, steady-state flow of a near-Newtonian fluid around a solid circular particle are developed and solved. The solution is obtained by computation of the dissipation relation and is based on the change of the shear rate in a shear flow of the suspension. The model is solved numerically. The resulting from the particle addition fluid is found to be more shear-thinning in comparison to the original. Experimental evidence from the literature supports the soundness of the present findings.► Cite this publication as follows:
Chernov V, Natan B: A simplified model for the evaluation of the rheological properties of a suspension of solids in a power-law fluid, Appl. Rheol. 22 (2012) 15163.
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