Piezoelectricity and pyroelectricity in polymers

Piezoelectric activities of polymers arise from poling-induced orientation of dipoles (class 1) and uniaxial orientation of chiral molecules (class 2). The former accompanies pyroelectricity while the latter produces pyroelectricity if the spontaneous shear strain is incorporated. Strong activities have been found in class 1, namely, ferroelectric polymers, polar polymers having large dielectric relaxations, and composites containing a large amount of PZT. Poling conditions, factors that determine piezoelectric and pyroelectric activities, and their basic mechanisms are discussed