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Delenclos S. Kolinsky C. Longuemart S. Hadj Sahraoui A. Buisine J. M. 《Journal of Thermal Analysis and Calorimetry》2002,70(2):549-558
The photopyroelectric (PPE) method is proposed as a sensitive technique to study a binary mixture of liquid crystals in a
contact preparation. The photothermal signal is generated while scanning the contact preparation. The crystal-smectic A, smectic
A-nematic, and nematic-isotropic interphase boundaries are detected. The displacement of these boundaries due to the variation
of the temperature is monitored. The study of these displacements allows us to draw the complete temperature-concentration
phase diagram of a binary mixtures.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
D. Dadarlat C. Neamtu N. Houriez S. Delenclos S. Longuemart A. Hadj Sahraoui 《The European physical journal. Special topics》2008,153(1):115-118
A method based on the sample's thickness scan of the
amplitude of the photopyroelectric (PPE) signal is proposed as an
alternative for thermal effusivity measurement of liquids. The proposed
method uses a combined amplitude-phase information and needs the knowledge
of the absolute values of the sample's thickness and phase of the signal.
The accuracy of the method is similar with that of previously reported
frequency-scanned methods, provided an accurate control of the cell's
(sample's) thickness is performed. A 479 Ws1/2/m2K room
temperature value for the thermal effusivity of silicon oil was found, with
a 0.1 μm step thickness control. 相似文献
3.
S. Delenclos A. Hadj Sahraoui C. Kolinsky J.M. Buisine 《Applied Physics A: Materials Science & Processing》2000,70(1):79-83
The photopyroelectric (PPE) method is proposed as a sensitive technique to study a binary mixture of liquid crystals in a
contact preparation. The photothermal signal is generated while scanning the contact preparation. The crystal (K)/smectic-A
(S
A), smectic-A/nematic (N), and nematic/isotropic (I) interphase boundaries are detected. The displacement of these boundaries
due to the variation of the temperature is monitored.
Received: 13 Oktober 1998 / Accepted: 7 July 1999 / Published online: 3 December 1999 相似文献
4.
D. Dadarlat M. Streza M. N. Pop V. Tosa S. Delenclos S. Longuemart A. Hadj Sahraoui 《Journal of Thermal Analysis and Calorimetry》2010,101(1):397-402
An alternative photopyroelectric (PPE) technique that combines the front detection configuration (FPPE) with the thermal wave
resonator cavity (TWRC) method is proposed. The theoretical analysis of the FPPE signal indicates that the configuration also
offers information about both fluid sample and backing solid material. It is demonstrated that the normalized phase of the
FPPE signal has an oscillating dependence as a function of the sample’s thickness. In the thermally thin regime for the sensor
and liquid sample, the method can be used for direct measurement of backing thermal effusivity. This article presents experimental
results on solid materials, with various values of thermal effusivity (Cu, brass, steel, glass, bakelite, and wood), used
as backings in the detection cell. A study of the sensitivity of the technique for different liquid/backing effusivity ratios
is performed. The main result of this article is the possibility of deriving the thermal effusivity of a solid sample (backing
material) by monitoring the thickness of a fluid with well-known properties. In such a way, the so-called coupling fluid is
not anymore a disturbing factor; however, its properties can be used to obtain the value of the thermal effusivity of a solid.
The method proved to be suitable especially for thermal effusivity investigations of low thermal conductors. An application
on polymer composites with different liquid/powder content is presented. 相似文献
5.
N. Houriez S. Delenclos S. Longuemart D. Dadarlat A. Hadj Sahraoui 《Laser Physics》2009,19(6):1345-1349
In this paper the first measurement of effective thermal parameters (thermal diffusivity, effusivity, conductivity and heat capacity) of Polymer Dispersed Liquid Crystal (PDLC) composites using the photopyroelectric (PPE) calorimetry is reported. The PPE technique is used in the standard “back” configuration and the cell has been designed for allowing the application of an electric field to the sample. Results show a dependence of the thermal parameters on the applied electric field which is explained by the reorientation of the liquid crystal molecules inside the droplets. 相似文献
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