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.