Thermo-electric properties

Thermo-electrical properties of PVA composite fibers with a large fraction of carbon nanotubes were studied by Miaudet et al. (52,53). Low temperature conductivity measurements showed that the conductivity depends on several factors the electronic properties of the nanotubes (54), the number and properties of intertube contacts, like in other polymer composites (55). The authors investigated also the behavior at high temperature. A strong increase of conductivity is observed in the vicinity of the glass transition of... 

The thermo-electric properties of metals are also altered when they absorb gases. If a thermocouple is made between a pure metal and a hydrogen-saturated metal, the pure metal is electronegative, and the thermal e.m.f. per V C. is(23)... 

Thermo-electric properties of conductive polymer nanofibers can be interesting for energy generation. In this case, a temperature gradient across a material is exploited to generate electricity (Seebeck effect). To this aim, one of the most important performance parameters is the dimensionless figure of merit ... 

Good thermo-mechanical and electrical properties rigidity impact strength fatigue endurance heat behaviour with continuous use temperatures from -196°C up to +220°C tribological properties for suitable grades. 

Good thermo-mechanical, chemical and electrical properties rigidity gamma irradiation resistance UHF transparency good creep resistance and fatigue behaviour low moisture uptake low shrinkage heat behaviour fire resistance low coefficient of thermal expansion. 

In 1999, M. Shaffer and A. Windle reported the first study of the thermo-mechanical and electrical properties of PVA/MWNT composite films (18). In this work, a high hydrolysis rate PVA was used (98-99%), with a large range molecular weight (between 85,000 and 146,000 g/mol). Water solutions of PVA were prepared at 90°C. 

One single property of filler - electric conductivity - affects many properties of the final products. These properties include electric insulation, conductivity, superconductivity, EMI shielding, ESD protection, dirt pickup, static decay, antistatic properties, electrocatafysis, ionic conductivity, photoconductivity, electromechanical properties, thermo-electric conductivity, electric heating, paintability, biocompati-bilify, etc. Possession of one of these properties in a polymer can make it useful in industiy and eveiyday use. Examples are given in Chapter 19. Here, the electrical... 

Thermo-electrometry is a group of thermo-analytical techniques in which an electrical property of a sample is monitored as a function of the temperature or time. An electrical property is seen as the response of a polymer when an electric field is applied to it. In contrast to metals, where electronic conduction is the only response to an electrical field, polymers may respond in different ways. A review of the different possibilities is given recently by C.C. Ku and R. Liepins in their "Electrical properties of polymers chemical principles [1]. Ku and Liepins separate the response of polymers to an electric field into two main parts ... 

Whatever the precise mechanisms of conduction, the macroscopic conductivity observed in any conducting polymer will depend strongly on the morphology of the sample and on whether it is oriented and, if so, to what degree, because these factors will influence both intra- and inter-chain mobility. For these reasons the conductivities of samples prepared under very similar conditions may differ considerably. The above account has merely attempted to indicate some of the types of process that may be involved in conduction in these relatively new materials, for which it is certain that no single mechanism can explain all the experimental results. Even when a particular theoretical description fits the conductivity, it cannot be accepted as the correct mechanism unless it can also accoimt for the observations of magnetic susceptibility, thermo-electric power, photoconductivity and other properties. 

Polyesteresterketone is partially crystalline polymer the thermo-stability of which depends on glassing temperature (amorphosity) and melting point (crystallinity) and increases with immobilization of macromolecules. The strong valence bonds define the high thermo-stability and longevity of mechanical and electrical properties at elevated temperature. 

The wider range of fuel choice for SOFC also calls in for advanced electrode materials for achieving the maximum performance. There is a considerable effort going on aimed at improving the thermo-catalytic, structural, and electrical properties of SOFC electrodes [54,17]. In a noted review, it is said that, Although cost is clearly the most important barrier to the widespread SOFC implementation, perhaps the most important technical barriers currently being addressed relate to the electrodes, particularly the fuel electrode or anode [37]. 

In 1908, aromatic polyimides were first reported by Bogert and Renstiaw [1]. Aromatic polyimides became well-known in 1950, after successful development of two-step polyimide synthesis by DuPont [2]. This class of polymers possesses a number of outstanding properties such as excellent thermal stability, mechanical strength, and electrical properties that have led to application in several fields from engineering thermoplastics to the aerospace and electronics industries, as well as for fibers and adhesives and in matrices for composite materials [3-5]. In addition, polyimides have high thermo-oxidative stability and chemical- and solvent-resistive properties, leading to many membrane-based applications... 

DMTA Dynamic Thermo-Mechanical Analysis measures the mechanical properties of materials under stress as a function of time, temperature, and frequency. DETA Dynamic Electrical Thermal Analysis measures the electrical properties of materials as a function of time, temperature, and frequency. 

The fist of publications [1-50] covers the period from 1958 to 1990, i.e., up to the very last years of the united Soviet Union. It includes only a small part of the publications and stiU reflects the wide variety of research on solid electrolytes at the IE US AS/IE UD AS and the journals publishing these results. There were many theoretical and experimental studies on electrochemical cells with solid electrolytes [1, 4, 5, 21, 39] and an extensive research on the phase composition of oxide ionic conductors [2] and their electric properties [3, 6, 8, 10, 13, 14, 17, 18, 20, 30, 34, 48]. Many papers were related to practical applications like sohd electrolyte degradation [33, 47] or application limits related to the electronic conductivity of the solid electrolytes [5, 30, 40, 43]. There were many publications on the implementation of different electrodes and on the kinetics of electrode processes [23,27, 31, 35, 36, 45], on investigations of the electrode overvoltage [7, 12, 25, 28], on impedance spectroscopy of solid electrolytes [19, 27], and on isotope exchange research [15,16]. The double layer and electrocapUlarity of solid electrolytes were studied in detail [9, 11, 19, 32, 44]. Systematic studies were performed on the thermo-EMF of different solid electrolytes [22,24,29], the EMF of electrochemical cells with solid electrolytes [26, 39], and the thermodynamics of oxygen in molten copper [41]. Applied research was focused on electrochemical oxygen pumps... 

Wan, Y, Xiong, C., Yu, J., and Wen, D. (2005) Efiect of processing parameters on electrical resistivity and thermo-sensitive properties of carbon-black/styrene— hutadiene-mbber composite membranes. Composites Science and Technology, 65, 1769-1779. 

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