Clearing Temperature

2016 ◽  
Author(s):  
Michael Hess ◽  
Giuseppe Allegra ◽  
Jiasong He ◽  
Kazuyuki Horie ◽  
Joon-Seop Kim ◽  
...  
Keyword(s):  
Clearing Temperature

Anomalie der elektrischen Leitfähigkeitsanisotropie von 4,4' -Di-n-hexyloxy-azoxybenzol

1974 ◽  
Vol 29 (10) ◽  
pp. 1523-1525 ◽  
Author(s):  
G. Heppke ◽  
F. Schneider
Keyword(s):  
Electric Conductivity ◽  
Smectic Phase ◽  
Tetrabutylammonium Picrate ◽  
Clearing Temperature

Abstract The electric conductivity of 4,4'-di-n-hexyloxyazoxybenzene is studied as a function of temperature for parallel and perpendicular alignment. Below the clearing temperature the ratio of anisotropy V=x||/x⟂ is found to be higher than unity. Its value decreases below unity when approaching the transition to the smectic phase. Increasing the concentration of the electrolyte tetrabutylammonium picrate yields an unexpected increase of the ratio of anisotropy.

Synthesis of Three Novel Aromatic Biazomethine Liquid- Crystalline Epoxy Resins and Curing Reaction with Aromatic Diamine

2011 ◽  
Vol 216 ◽  
pp. 34-38
Author(s):  
Jun Gang Gao ◽  
Xiao Na Zhang ◽  
Yong Gang Du
Keyword(s):  
Melting Point ◽  
Epoxy Resins ◽  
Liquid Crystalline ◽  
Diphenyl Ether ◽  
Hydroxyl Group ◽  
Aromatic Diamine ◽  
Curing Reaction ◽  
Ozawa Equation ◽  
Liquid Crystalline Epoxy ◽  
Clearing Temperature

Three class of novel liquid crystalline epoxy resins containing azomething groups: N,N’-Bis[4-(2,3-epoxypropoxy)benzylidene]-4,4-diamino-diphenyl ether (p-BEPBDDE), N,N’-Bis[4-(2,3-epoxypropoxy)benzylidene]-4,4-diamino-diphenyl methane (p-BEPBDDM) and N,N’-Bis[(4-(2,3-epoxypropoxy)-benzyliden)-1,4- phenylene diamine] (p-BEPBPD) were synthesized and characterized. The results show that p-BEBDDE and p-BEBDDM belong to smectic texture and melting point is 239.5 and 178 oC, respectively. The p-BEPBD is nematic texture between its melting temperature (Tm) of 192 oC and clearing temperature (Ti) of 238 oC. The curing reaction can be described by Ozawa equation, and the alcohol-hydroxyl group can accelerate the curing reaction and decrease Ea in DSC experiment.

Linear and Non-linear Dielectric Pretransitional Behavior Near the Isotropic-nematic Phase Transition for 4-cyano-4-n-pentylbiphenyl (5CB)

2002 ◽  
Vol 57 (5) ◽  
pp. 244-246 ◽  
Author(s):  
G. Czechowski ◽  
J. Jadżyn ◽  
J. Zioło ◽  
S. J. Rzoska ◽  
M. Paluch
Keyword(s):  
Phase Transition ◽  
Nematic Phase ◽  
Dynamic Properties ◽  
Experimental Methods ◽  
Dielectric Absorption ◽  
Temperature Discontinuity ◽  
Non Linear ◽  
Clearing Temperature ◽  
Nematic Phases ◽  
Permittivity Measurements

Linear and non-linear dielectric permittivity measurements for n-pentylcyanobiphenyl 5CB are presented. By two different experimental methods the same value of the temperature discontinuity for the isotropic-nematic transition was obtained. Broadband dielectric relaxation tests showed a significant influence of the pretransitional behavior on the dynamic properties above and below the nematic clearing temperature (TI-N). The form of the loss curves is clearly non-Debye’an and can be portrayed within the Cole-Davidson approximation (CD). In the isotropic and nematic phases the CD parameter βCD drops on approaching the clearing temperature. This is connected with the broadening of the dielectric absorption width.

PVT Measurements on 4′-n-Octyl-Biphenyl-4-Carbonitrile (8CB) up to 300 MPa

1998 ◽  
Vol 53 (9) ◽  
pp. 787-792
Author(s):  
M. Sandmann ◽  
A. Würflinger
Keyword(s):  
Volume Change ◽  
Atmospheric Pressure ◽  
Volume Changes ◽  
First Order ◽  
Smectic A ◽  
Enthalpy Changes ◽  
Second Order Transition ◽  
Clearing Temperature ◽  
Pvt Measurements ◽  
Period Of Oscillation

Abstract P, Vm , Tdata have been measured for the smectic, nematic and isotropic phases of 4'-n-octyl-biphen-yl-4-carbonitrile (8CB) in the temperature range 300-370 K and pressures up to 300 MPa. At atmospheric pressure all phase transitions appear to be of first order due to a discontinuity in the density. The volume change at the smectic A -nematic transition is only a tenth of the volume change at the clearing temperature. At moderate pressures below 80 MPa the SA -N transition could be detected as a discontinuity in the period of oscillation in measurements with a high-pressure vibrating tube densimeter. At higher pressures the discontinuity seems to die away, possibly indicating a change from first order to second order transition. From the volume changes and the slopes of the transition lines we calculate the enthalpy changes at the phase transition. The p, Vm , T data enable us to calculate the volume part of the entropy and the molecular field parameter γ=δln TNI/δln VNI .

Pseudo Clearing Temperature in Binary Polymer-Nematic Solutions

1980 ◽  
Vol 45 (20) ◽  
pp. 1645-1648 ◽  
Author(s):  
A. Dubault ◽  
C. Casagrande ◽  
M. Veyssié ◽  
B. Deloche
Keyword(s):  
Binary Polymer ◽  
Clearing Temperature

scholarly journals Doping liquid crystals with nanoparticles. A computer simulation of the effects of nanoparticle shape

2016 ◽  
Vol 18 (4) ◽  
pp. 2428-2441 ◽  
Author(s):  
Silvia Orlandi ◽  
Erika Benini ◽  
Isabella Miglioli ◽  
Dean R. Evans ◽  
Victor Reshetnyak ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Monte Carlo ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Monte Carlo Simulations ◽  
Orientational Order ◽  
Nanoparticle Shape ◽  
Nanoparticle Dispersions ◽  
Molecular Scale ◽  
Clearing Temperature

Molecular-scale Monte Carlo simulations of liquid crystal-nanoparticle dispersions show the effect on the orientational order and on the clearing temperature of shape and concentration of the dopant nanoparticles.

scholarly journals Adjacent functional group effects on the assembly of columnar liquid crystals

2020 ◽  
Vol 98 (7) ◽  
pp. 379-385
Author(s):  
Carson O. Zellman ◽  
Danielle Vu ◽  
Vance E. Williams
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Self Assembly ◽  
Room Temperature ◽  
Functional Group ◽  
The Self ◽  
Clearing Temperature ◽  
Crystal Phases ◽  
Potential Strategy ◽  
The Impact

Although the impact of individual functional groups on the self-assembly of columnar liquid crystal phases has been widely studied, the effect of varying multiple substituents has received much less attention. Herein, we report a series of dibenzo[a,c]phenazines containing an alcohol or ether adjacent to an electron-withdrawing ester or acid. With one exception, these difunctional mesogens form columnar phases. The phase behavior appeared to be dominated by the electron-withdrawing substituent; transition temperatures were similar to derivatives with these groups in isolation. In most instances, the addition of an electron-donating group ortho to an ester or acid suppressed the melting temperature and elevated the clearing temperature, leading to broader liquid crystal thermal ranges. This effect was more pronounced for derivatives functionalized with longer chain hexyloxy groups. These results suggest a potential strategy for controlling the phase ranges of columnar liquid crystals and achieving room temperature mesophases.

Rupture of Polydomain and Monodomain Liquid Crystal Elastomer

2016 ◽  
Vol 08 (07) ◽  
pp. 1640001 ◽  
Author(s):  
Wei Fan ◽  
Zhijian Wang ◽  
Shengqiang Cai
Keyword(s):  
Liquid Crystal ◽  
Fracture Energy ◽  
Shear Test ◽  
Pure Shear ◽  
Mechanical Stretch ◽  
Energy Measurement ◽  
Synthetic Process ◽  
Liquid Crystal Elastomer ◽  
Active Structures ◽  
Clearing Temperature

Liquid crystal elastomer (LCE) has been recently explored extensively to make diverse active structures and devices. Depending on synthetic process, LCE can be made either polydomain or monodomain when ambient temperature is below isotropic clearing temperature. In the applications, LCE may be subjected to large mechanical stretch or force and break apart. The capability of predicting the rupture of LCE under different loading conditions is crucial for the applications. However, according to our knowledge, there is no report on fracture energy measurement of LCE. In this paper, we measured fracture energy of both monodomain and polydomain LCEs using pure shear test. We found that polydomain LCE has significantly higher fracture energy than monodomain one. We suggest that the increase of fracture energy in polydomain LCE is attributed to stretch-induced polydomain-to-monodomain transition near the crack tip of the material.

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