Primarily, newly developed, high sensitive and accurate methods for thermal characterization of liquids using photothermal radiometry are presented. Two experimental configurations are suggested, tested and validated with usual liquid materials. These methods are used to study polymer dispersed liquid crystal samples. Dynamic thermal properties of samples are analysed verses amplitude varying applied electric field with constant frequency as well as versus frequency varying electric field with constant amplitude. Our results clearly show the thermal properties of the samples are prone to depolarizing field effects at the lower frequencies of the applied electric field. The experimental results are modeled against existing theories to predict electric properties of the sample composites. Second part of the manuscript describes the development of a novel photothermal technique based on thermoelectric effect. This technique is particularly useful for thermally characterizing thermoelectric materials without using a separate sensor for measuring induced temperature changes. A theoretical and experimental study is presented. The experiments are done on polyaniline - carbon nanotube composite pellets by measuring Seebeck voltage generated by the samples upon heating by a modulated laser beam. Additional infrared radiometry experiments are done on the same samples and the results are in good agreement with those previously found. Later on, the possibility of photothermoelectric materials to be used as sensors for finding thermal transport properties of materials with a thermal wave resonant cavity is suggested.
| Identifer | oai:union.ndltd.org:CCSD/oai:tel.archives-ouvertes.fr:tel-00982712 |
| Date | 26 June 2013 |
| Creators | Kuriakose, Maju |
| Publisher | Université du Littoral Côte d'Opale |
| Source Sets | CCSD theses-EN-ligne, France |
| Language | English |
| Detected Language | English |
| Type | PhD thesis |
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