Przeglądaj {{ collection }} wg Autor "Wojciechowski, Marek"

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Dielectric and optical properties of liquid crystal 1H6Bi
(Wydawnictwo Politechniki Łódzkiej, 2012) Wojciechowski, Marek; Tykarska, Marzena; Bąk, Grzegorz
Recently synthesized antiferroelectric liquid crystal 1H6Bi shows special optical properties related to change in handedness of the ferroelectric helix. The broadband dielectric measurements of this compound has been carried out, a number of dielectric relaxation modes corresponding to various temperatures and LC phases have been detected. The characteristic parameters of these modes are presented and compared with the optical data.
Dielectric characteristics of antiferroelectric liquid crystalline mixture
(Wydawnictwo Politechniki Łódzkiej, 2008) Wojciechowski, Marek
Mixture of liquid crystals, with induced antiferroelectric phase has been studied by means of dielectric spectroscopy. The dielectric measurements were carried out in a cell with gold electrodes at planar orientation. The characteristic of dielectric relaxation modes in all phases existing in the mixture are presented.
Dielectric properties of antiferroelectric liquid crystal 4F5Bi(2F)
(Wydawnictwo Politechniki Łódzkiej, 2011) Wojciechowski, Marek; Tykarska, Marzena
Recently synthesized an antiferroelectric liquid crystal compound has been studied by means of dielectric spectroscopy. The dielectric measurements were curried out in a cell with gold electrodes at planar orientation. The characteristics of dielectric relaxation modes in all phases existing in the investigated compound are presented.
Dielectric properties of ferrielectric phase induced in liquid crystal mixture
(Wydawnictwo Politechniki Łódzkiej, 2010) Wojciechowski, Marek
Mixtures of two liquid crystalline compounds (which do not exhibit antiferroelectric phases separately) show ferrielectric phase in a broad temperature range in 5:5 and 3:7 compositions. The dielectric spectroscopy technique was used for investigation of collective molecular motions in these mixtures. Two relaxation modes were detected in the ferrielectric phase. The temperature dependence of the parameters of the dielectric relaxation modes of ferrielectric phase are compared and discussed.
Dielectric properties of ferrielectric subphase of liquid crystal MHPOPB
(Wydawnictwo Politechniki Łódzkiej, 2013) Wojciechowski, Marek; Tykarska, Marzena; Bąk, Grzegorz
The antiferroelectric liquid crystal with relatively broad temperature range of ferrielectric subphase was chosen for dielectric investigations of this subphase. In the ferrielectric subphase, collective molecular motions were registered as a ferrielectric Goldstone mode. Theory of ferroelectric Goldstone mode was applied to the registered ferrielectric subphase to obtain rotational viscosity.
Dielectric properties of ferroelectric liquid crystalline material with chiral nematic phase.
(Wydawnictwo Politechniki Łódzkiej, 2015) Wojciechowski, Marek; Bąk, Grzegorz W.; Tykarska, Marzena
The ferroelectric liquid crystal with nematic N* phase has been investigated using broadband low frequency dielectric spectroscopy. The dielectric relaxation modes related to a ferroelectric Goldstone mode were detected only in a narrow temperature range. Well defined relaxation process was detected in the SmB* phase at about 90 Hz.
Dielectric relaxation modes in antiferroelectric liquid crystal mixture
(Politechnika Łódzka, 2007) Wojciechowski, Marek
Mixture of liquid crystals, with induced antiferroelectric phase has been studied by means of dielectric spectroscopy. The dielectric measurements were carried out in a cell with gold electrodes at planar orientation. The characteristic of dielectric relaxation modes in all phases existing in the mixture are presented. The results are compared with the results obtained for the same mixture in the cell with ITO electrodes.
Dielectric relaxation modes in liquid crystalline mixture
(Wydawnictwo Politechniki Łódzkiej, 2009) Wojciechowski, Marek
Mixture of two liquid crystalline compounds (which do not exhibit antiferroelectric or ferrielectric phase separately) shows ferrielectric phase in a broad temperature range. The dielectric spectroscopy technique was used for investigation of collective molecular motions in the mixture. Two relaxation modes were detected in the ferrielectric phase and the soft mode in the SmA phase. The temperature dependence of the parameters of the dielectric relaxation modes are presented and discussed.
Main properties of sands hydrophobized by alkoxysilane emulsions
(2014) Wojciechowski, Marek; Baryła, Patrycja; Lefik, Marek
The results of laboratory tests and geotechnical view on sands hydrophobized by alkoxysilane emulsions are presented. For the soils subjected to this process, very low permeability and no capillary elevation was observed. Laboratory tests also indicate that other physical and mechanical properties of hydrophobized sands remain nearly untouched, i.e., the considered hydrophobisation process does not reduce the strength of soils. Properly composed alkoxysilane emulsions can also solidify in pores to produce a stabilizing silicate binder. The filtration barriers in ground and soil stabilization are thus considered as possible applications of the hydrophobized soils. The process of treatment of granular soils with alkoxysilanes is neutral for the environment and the cost of implementation of the method is relatively low.