Effect of temperature on piezoelectricity in wood

The piezoelectric modulus of Wood has been measured in the temperature range of −170°C. to +150°C. The kind of wood investigated is hinoki (Chamaecyparis obtusa Endl.). When a sinusoidal stress is longitudinally given to the thin plate specimen, the polarization is produced in the direction perpendicular to the surface of the plate. It has been found that the piezoelectric modulus generally increases with the rise of temperature. However, the modulus-temperature curve shows discontinuous changes in slope at about −80, 30, and 130°C. These temperatures seem to be associated with transitions in amorphous regions of cellulose and other macromolecules in wood. Gamma-ray irradiation up to 1.7 × 108 rad causes little variation in the magnitude and the temperature dependence of the piezoelectric modulus. Treatments with liquid ammonia, sodium hydroxide, and ethylenediamine result in a large increase in the magnitude and the temperature dependence of the piezoelectric modulus. The crystal lattices of cellulose II and III are more favorable than that of cellulose I for producing the piezoelectric effect.