Thermoelectric polymer-matrix structural and nonstructural composite materials

This paper reviews thermoelectric polymer-matrix composites, including nonstructural and structural materials. The structural materials are continuous fiber composites; the nonstructural materials are discontinuously reinforced composites and polymer-polymer composites. A thermoelectric structural composite uses the reinforcing continuous fibers to enhance the electrical conductivity. The directionality of the continuous fibers allows tailoring of the thermoelectric behavior in various directions, particularly the through-thickness direction and the fiber direction. The use of laminae with dissimilar fibers (with opposite signs of the thermoelectric power) that are in different directions provides an array of unmodified and ordinarily made interlaminar interfaces, which serve as an array of thermocouple junctions that are based on the fiber-dominated thermoelectric behavior in the fiber direction of each lamina. By modification through positioning fillers at the interlaminar interface, the filler-dominated through-thickness thermoelectric behavior can be tailored. By using dissimilar fillers at the interlaminar interface, dissimilar composites that exhibit opposite signs of the thermoelectric power are obtained. Nonstructural thermoelectric composites exhibit a large range of ZT values, depending on the composition, structure and method of preparation. Keywords: Thermoelectric, Polymer-matrix composite, Polymer-polymer composite, Fiber, Structural composit

Synchrotron X-ray diffraction study of the room temperature incommensurate phase in graphite-bromine intercalation compound

Synchrotron X-ray and a four-circle diffractometer were used to study the room temperature incommensurate phase in stage-2 graphite-bromine prepared with single crystal graphite in bromine liquid. The two strongest in-plane superlattice reflections and the strongest satellite peak were scanned along the most incommensurate direction of the lattice between 302 K and 324 K. The incommensurate-commensurate transition at 319 ± 1 K caused disappearance of the incommensurate peaks and appearance of the commensurate one. Possible models of the incommensurate phase are presented.On a utilisé des rayons X émis par un synchrotron en coordination avec un diffractomètre à quatre cercles dans le but d'étudier la phase incommensurable dans un composé graphite-bromine en second stade à température ambiante. Le composé graphite-brome a été préparé à partir d'un cristal unique de graphite. Les réflexions de super réseau les plus fortes et les satellites les plus importants ont été balayés le long de la direction la plus incommensurable du réseau entre 302 K et 324 K. La transition incommensurable-commensurable qui a lieu à 319 ± 1 K produit la disparition des pics incommensurables et l'apparition du pic commensurable. Nous présentons des modèles possibles pour la phase incommensurable

Effects of material and test parameters on the wear behavior of particulate filled composites Part 1: SiC-epoxy and 13; Gr-epoxy composites

Studies were carried out on a (RT) cure epoxy (LY556xFE;HY951) composite system13; comprising of silicon carbide (SiC) and graphite (Gr) particulates. Results showed that13; the wear resistance and coefficient of friction of both the composites increased with sliding13; distance and contact load (contact pressure) for the range of filler contents (5x2013;40% wt) considered.13; The Gr-composite exhibited its distinct (superior) tribological feature compared to the13; SiC-composite. A wear endurance index has been identified from the experimental data, to serve13; as a parameter to assess the long term wear life (residual wear life) of these composites