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Effect of new types of synthetic waxes designed for low-temperature asphalt mixtures
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
L. Benešová, J. Mastný, J. Valentin
Volumetric rotational viscosity is an important characteristic for the description of bituminous binder workability. The characteristic is mainly important from the point of view of bitumen transport and pumping e.g. in the mixing plant. The rotational viscosity test was carried out according to the standard EN 13302 using a spindle rotational viscometer. The values determined with shear rate of 6.8 s-1 (the shear rate considered the indicative parameter for bituminous binder workability assessment in the U.S.) at different temperatures were measured as expected, lower for all versions of binders with wax-based additives on the test than for the reference bitumen. The viscosity reductions are more distinctive in most variants under lower temperatures; with respect to the option of reducing compaction temperature of asphalt mixtures, this is a more important value. The lowest viscosity was achieved for binders with 3% T39A and if a combination of waxes E10K and RH was prepared, while similar results were recorded by a version with a higher quantity of BIT as well. The effect of synthetic waxes on rotational viscosity is shown in Figure 1. Measurements were taken for other shear rates and for a temperature range of 100–150°C, which allows plotting the so-called flow curves (Fig. 2). The curves show that at the lowest temperature (100°C), not all versions have viscosities lower than the reference bitumen. A sharp decline of viscosity is noticeable in the temperature range of 100–120°C. An exception is the A20K wax where the viscosity only becomes lower when compared to the reference binder from 130°C; however, this is a finding already verified for other types of fatty acid amides, too (Butz 2008, Valentin 2014).
Dielectric and electro-optical properties of ferric oxide nanoparticles doped 4-octyloxy-4’ cyanobiphenyl liquid crystal-based nanocomposites for advanced display systems
Published in Liquid Crystals, 2021
Pankaj Kumar Tripathi, Aradhana Roy, Abhishek Kumar Misra, Kamal Kumar Pandey, Rajiv Manohar, Y. S. Negi
The splay constant (K11) and rotational viscosity (γ) of an aligned LC sample cell represents internal friction between LC directors and applied electric field. The magnitude of rotational viscosity depends on the molecular structure, constituent, intermolecular association and temperature. The K11 and γ are very important parameters for the application electro-optical devices. Splay elastic constant and rotational viscosity has been investigated by the measurement of dielectric parameter and threshold voltage for the pristine and Fe2O3 nanocomposites at 74°C. The K11 and γ were calculated by using equations,
Increasing the rewriting speed of ORW e-paper by electric field
Published in Liquid Crystals, 2018
L. Wang, J. Sun, H. Liu, V. G. Chigrinov, H. S. Kwok
where is a material parameter. Generally, rotational viscosity is a complicated function of molecular shape, moment of inertia, activation energy and temperature. Among these factors, activation energy and temperature are the most crucial ones. The activation energy depends on the detailed intermolecular interactions. An empirical rule is that for every 10 degrees of temperature rise, the rotational viscosity drops by about two times.
Evaluation of elastomer–plastomer vulcanised modifiers for using as bitumen binder modifier
Published in International Journal of Pavement Engineering, 2022
Mahmoudreza Favakeh, Saeed Bazgir, Morteza Karbasi, Mohammad Zia Alavi, Ali Abdi
The viscosity of modified binders was measured using the rotational viscosity test to evaluate the pumpability and the workability of binders during asphalt mix production. The rotational viscosity is calculated using the torque required to maintain a constant rotational speed (usually 20 rpm). According to the Superpave PG criteria, the viscosity should be less than 3.0 Pa s at the elevated temperature of 135°C.