Rheology


Rheology is the study of the flow of matter. Acting of external force (shear stress times shear area) on a material causes its flowing (deformation). The measure of this external force and the rate of deformation is so-called shear viscosity characterising the measure of internal fluid friction. Based on shear viscosity, the materials can be divided into two basic groups – Newtonian and non-Newtonian. Newtonian materials are such materials whose shear viscosity does not change with changing of the shear rate at a given temperature. On the other hand, the viscosity of non-Newtonian liquid (e.g. ketchup, mayonnaise, blood) is dependent on the shear rate. The non-Newtonian liquids can be further divided into plastic, pseudo-plastic and dilatant.

The rheological group at the Institute of Hydrodynamics studies non-Newtonian liquids, mainly the polymeric materials. These materials exhibit strong nonlinear rheological properties caused by their viscous and elastic effects. The knowledge of the rheological properties of the polymeric materials plays an important role for the producers and manufacturers of the materials and also for the tool and device makers. For the producers of the materials, the rheological properties (shear and elongational) are essential guideline for proposing of new materials (homopolymers, copolymers) with a specific properties suitable for a given process (extrusion, injection moulding, thermoforming, blow moulding) or product (pressure tubes, artificial joints). For the manufactures, the knowledge of material rheology is essential for the proper process conditions (temperature, pressure, cooling rate, etc.). The rheological properties of the materials are also important for the tools makers due to the possibility to simulate the complex flow situations in 3D simulating software.

Based on these needs given mainly by the development of new materials and by the processing, our group deals with the topics specified below.

Zelenková, J.; Pivokonský, R.; Filip, P., 2017. Two ways to examine differential constitutive equations: initiated on steady or initiated on unsteady (LAOS) shear characteristics. Polymers. Vol. 9, no. 6, article no. 205. ISSN 2073-4360.

Peer, P.; Filip, P.; Polášková, M.; Kucharczyk, P.; Pavlínek, V., 2016. The influence of sonication of poly(ethylene oxide) solutions to the quality of resulting electrospun nanofibrous mats. Polymer Degradation and Stability. Vol. 126, April, pp. 101-106. ISSN 0141-3910.

Pivokonský, R.; Filip, P.; Zelenková, J., 2016. Flexibility of three differential constitutive models evaluated by large amplitude oscillatory shear and Fourier transform rheology. Polymer. Vol. 104, no. 8, pp. 171-178. ISSN 0032-3861.

Slobodian, P.; Říha, P.; Olejník, R.; Benlikaya, R., 2016. Analysis of sensing properties of thermoelectric vapor sensor made of carbon nanotubes/ethylene-octene copolymer composites. Carbon. Vol. 110, December, pp. 257-266. ISSN 0008-6223.

Slobodian, P., Cvelbar, U., Říha, P., Olejnik, R., Matyas, J., Filipič, G., Watanabe H., Tajima, S., Kondo, H., Sekine, M., Hori, M., 2015. High sensitivity of carbon nanowalls based sensor for detection of organic vapours, RSC Advances, 2015, 5, 90515 – 90520.

Slobodian, P.,Říha, P.,Olejnik, R. and Saha, P., 2015. Functionalized Multi-Walled Carbon Nanotube Paper for Monitoring Chemical Vapors, J. Nanosci. Nanotechnol. 15, 4003-4008.

Pivokonský R.; Filip P., 2014. Predictive/fitting capabilities of differential constitutive models for polymer melts—reduction of nonlinear parameters in the eXtended Pom-Pom model. Colloid Polym. Sci. 292, 2753-2763.

Peer P., Stenička M., Pavlínek V., Filip P., 2014. The storage stability of polyvinylbutyral solutions from an electrospinnability standpoint. Polymer Degradation and Stability 105, 134-139.

Ledvinková, B.; Kosek, J., 2013. The effects of adhesive forces on the collision behavior of polyolefin particles. Powder Technology 243, 27-39.

Morávková, T., Filip, P., 2013. The Influence of Emulsifier on Rheological and Sensory Properties of Cosmetic Lotions. Advances in Materials Science and Engineering, Vol. 2013, Article ID 168503.