Electromechanical Properties of Poly-L-Lactic Acid

The electromechanical coupling coefficient, the piezoelectric constant, the elastic compliance constant and the mechanical quality factor for a poly-L-lactic acid (PLLA) plate elongated to 4 times the original length were determined by a self-resonant method. k 14 =0.064, d 14 =9.82×10 -12 C/N, s 44 E =9.28×10 -10 m 2 /N and Q m =30.3 were obtained at room temperature for a 0° X -cut square plate. It is noted that elongated PLLA films have no spontaneous polarization, unlike poled polymers such as poly(vinylidene fluoride) (PVDF), but still have a large shear piezoelectric constant.