METHOD OF DECAYING FLOW IN RHEOLOGY OF POLYMERIC POROUS FILMS FILLED BY LIQUID CRYSTALS
https://doi.org/10.32362/2500-316X-2017-5-5-25-39
Abstract
The rheological properties of nematic liquid crystals (NLC) - a two-component mixture of 2/3 parts of p-n-butyl-p-methoxyazoxybenzene and 1/3 parts of p-n-butyl-p-heptanoylazoxybenzene (ZhK-440, NIOPIK) and 4-cyano-4'-pentylbiphenyl (5CB, Merck) filling a porous polymer (PET) matrix with submicron pore diameters are studied. The experiments were fulfilled using the decaying Poiseuille flow arising in a polymer porous film of 23 μm thickness under the action of hydrostatic pressure gradient decreasing with time. In this case a polymer matrix can be considered as a number of cylindrical capillaries connected by a parallel schema. It results in an essential decrease in the hydrodynamic resistance of the system in comparison with the resistance of each capillary. The Newtonian nature of the flow was established, and the effective shear viscosities of NLC for different temperatures were determined. An analysis of the experimental data was carried out taking into account the effect of weak surface anchoring on the orientational structure of the liquid crystals. The data obtained can be used to calculate the technical characteristics of liquid crystal photonic devices.
About the Authors
S. V. Pasechnik
Moscow Technological University (Physico-Technological Institute)
Russian Federation
Russian Federation
D. V. Shmeliova
Moscow Technological University (Physico-Technological Institute)
Russian Federation
Russian Federation
A. V. Torchinskaya
Moscow Technological University (Physico-Technological Institute)
Russian Federation
Russian Federation
O. A. Semina
Moscow Technological University (Physico-Technological Institute)
Russian Federation
Russian Federation
A. A. Dyukin
Moscow Technological University (Physico-Technological Institute)
Russian Federation
Russian Federation
References
1. de Gennes Pierre Gilles. The Physics of Liquid Crystals. Oxford University Press, 1974. 346 p.
2. Kutnjak Ž., Kralj S., Lahajnar G., Žumer S. Calorimetric study of 8CB liquid crystal confined to controlled-pore glasses // Phys. Rev. 2003. E 68. P. 021705-1–021705-11.
3. Semerenko D.A., Shmeliova D.V., Pasechnik S.V., Murauskii A.V., Tsvetkov V.A., Chigrinov V.G. Optically controlled transmission of porous polyethylene terephthalate films filled with nematic liquid crystal // Optics Lett. 2010.V. 35. № 13. P. 2155–2157.
4. Chopik A.P., Pasechnik S.V., Semerenko D.A., Shmeliova D.V., Dubtsov A.V., Srivastava A.K., Chigrinov V.G. Electro-optical effects in porous PET films filled with liquid crystal: new possibilities for fiber optics and THZ applications // Optics Lett. 2014.V. 39. № 6. P. 1453–1456.
5. Chigrinov V.G. Liquid Crystal Devices: Physics and Applications. Artech House, 1999. 357 p.
6. Pasechnik S.V., Chopik A.P., Shmeliova D.V., Drovnikov E.M., Semerenko D.A., Dubtsov A.V., Zhangb W., Chigrinov V.G. Electro-kinetic phenomena in porous PET films filled with liquid crystals // Liquid Cryst. 2015. V.7. P. 1537–1542.
7. Pasechnik S.V., Chigrinov V.G., Shmeliova D.V., Tsvetkov V.A., Voronov A.N. Anisotropic shear viscosity in nematic liquid crystals: new optical measurement method // Liquid Cryst. 2004. V. 31. P. 585–592.
8. Pasechnik S.V., Krekhov A.P., Shmeleva D.V., Nasibullaev I.Sh., Tsvetkov V.A. Orientational instability in a nematic liquid crystal in a decaying poiseuille flow // J. Exp. & Theor. Phys. 2005. V. 100. № 4. P. 804–810.
9. Pasechnik S.V., Semina O. A., Shmeliova D. V., Dubtsov A.V., Chigrinov V. G., Jatong D. V. Sun photocontrolled surfaces in rheology of liquid crystals // Mol. Cryst. Liq. Cryst. 2015. V. 611. P. 81–89.
10. Pasechnik S.V., Shmeliova D.V., Semerenko D.A., Voronov A.N., Semina O.A. Modified optical method for measurements of anisotropic shear viscosities of nematic liquid crystals // Liquid Сrystals and Their Appl. 2011.V. 3(37). P. 41–46.
11. Barnik M.I., Belyaev S.V., Grebenkin M.F., Rumyantsev V.G., Seliverstov V.A., Tsvetkov V.A., Shtykov N.M. Electrical, optical and visco-elastic properties of the liquid crystal mixture of azoxy // Crystallography. 1978. V. 23(4). P. 805–810.
12. Bradac Ž., Kralj S., Zumer S. Molecular dynamics study of nematic structures confined to a cylindrical cavity // Phys Rev. 1998. E. 58(6). P. 7447–7454.
13. Crawford G.P., Allender D.W., Doane J.W. Surface elastic and molecular-anchoring properties of nematic liquid crystals confined to cylindrical cavities // Phys. Rev. 1992. V. 45. P. 8693–8708.
14. Allender D.W., Crawford G.P., Doane J.W. Determination of the liquid-crystal surface elastic constant K24 // Phys. Rev. Lett. 1991. V. 67. P.1442–1445.
15. Tkachenko V., Dyomin A.A., Tkachenko G.V., Abbate G., Sukhoivanov I.A. Electrical reorientation of liquid crystal molecules inside cylindrical pores for photonic device applications // J. Opt. A: Pure Appl. Opt. 2008. V. 10. P. 055301–055306.
16. Belyaev V.V. Viscosity of nematic liquid crystals. Moscow: FIZMATLIT, 2002. 224 p. (in Russ.).
17. Maksimochkin G.I., Shmeliova D.V., Pasechnik S.V., Dubtsov A.V., Semina O.A., Kralj S. Orientational fluctuations and phase transitions in 8CB confined by cylindrical pores of the PET film // Phase Transitions. 2016. V. 89. P. 846–855.
18. Tsvetkov V.A. Attempt of direct measuring of near surface shear viscosity // Mol. Cryst. Liq. Cryst. 2005. V. 436. P. 1157–1170.
19. Pasechnik S.V., Chigrinov V.G., Shmeliova D.V. Liquid Crystals: Viscous and Elastic Properties in Theory and Applications. New York: Wiley, 2009. 424 p.
20. Kneppe H., Shneider F. Determination of the viscosity coefficients of the liquid crystal MBBA // Mol. Cryst. Liq. Cryst. 1981. V. 65. P. 23–28.
21. Fisher J., Frederickson A. G. Interfacial effects on the viscosity of a nematic mesophase // Mol. Cryst. Liq. Cryst. 1969. V.8. P. 267–284.
22. Tseng H.C., Silver D.L., Finlayson B. A. Application of the continuum theory to nematic liquid crystals // Phys. Fluids. 1972. V. 15. P. 1213–1222.
Review
For citations:
Pasechnik S.V., Shmeliova D.V., Torchinskaya A.V., Semina O.A., Dyukin A.A. METHOD OF DECAYING FLOW IN RHEOLOGY OF POLYMERIC POROUS FILMS FILLED BY LIQUID CRYSTALS. Russian Technological Journal. 2017;5(5):25-39. (In Russ.) https://doi.org/10.32362/2500-316X-2017-5-5-25-39
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