High piezoelectric performance of poly(lactic acid) film manufactured by solid-state extrusion

Recently, the application of uniaxially stretched poly(L-lactic acid) (PLLA) films to speakers, actuators, and pressure sensors has been attempted, taking advantage of their piezoelectric performance. However, the shear piezoelectric constant d(14) of uniaxially stretched PLLA film is conventionally 6-10 pC N-1. To realize a high sensitivity of pressure sensors, compact speakers, and actuators, and a low driving voltage, further improvement of the piezoelectric performance is desired. In this study, we carried out solid-state extrusion (SSE) to stretch and orient poly(D-lactic acid) (PDLA) and verified its effects on piezoelectric performance. By SSE, we were able to improve the mechanical strength and elastic modulus of PDLA samples. Furthermore, the d(14) of the samples was significantly increased to approximately 20 pC N-1. (C) 2014 The Japan Society of Applied Physics