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

Abstract

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(Dlactic 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 .

Direct Piezoelectric Coefficient Measurements of PVDF and PLLA under Controlled Strain and Stress

“…From the calculated coefficients (Table 1), the PLLA working in d14 mode is comparable to the PVDF in d31 mode for the actuation. The tested PLLA film presents piezoelectric d14 values below those of literature (10 × 10 −12 C.N −1 [1] and 18.9 × 10 −12 C.N −1 [2]) as it is still under development. …”

“…They develop natural piezoelectricity after mechanical stretching. For the PLA, the stretching creates a nonchiral film poly-L-lactic acid (PLLA) presenting only one shear piezoelectric constant d14 between 10 × 10 −12 C.N −1 [1] and 18.9 × 10 −12 C.N −1 [2]. This biodegradable polymer presents the advantage of not being pyroelectric, ensuring an absence of drift with the temperature.…”

Polarized FT-IR Study of Uniaxially Aligned Electrospun Poly(DL-Lactic Acid) Fiber Films

“…There are two optical isomers, i.e., L-and D-lactic acid, therefore, PLAs polymerized from either the poly-L-lactic acid (PLLA) or poly-D-lactic acid (PDLA) are also chiral. It is known that orienting the PLLA and PDLA films by stretching imparts shear piezoelectricity [3][4][5][6][7][8][9]. In contrast, racemic mixture of PLLA and PDLA, i.e., poly-DL-lactic acid (PDLLA), have not shown piezoelectricity.…”

Mechanical Energy‐to‐Electricity Conversion of Electron/Hole‐Transfer Agent‐Doped Poly(Vinylidene Fluoride) Nanofiber Webs

“…Various mechanical‐to‐electrical energy conversion devices have been developed using the principles such as electromagnetic, piezoelectric, or triboelectric . Piezoelectric materials, especially piezoelectric polymers, e.g., poly(vinylidene fluoride) (PVDF) and its copolymers, offer advantages in developing flexible devices with high strain level and stability …”

“…[3][4][5][6] Piezoelectric materials, especially piezoelectric polymers, e.g., poly(vinylidene fluoride) (PVDF) and its copolymers, offer advantages in developing flexible devices with high strain level and stability. [4,[7][8][9][10][11] (2 of 6) 1600451 randomly-oriented electrospun PVDF nanofiber webs can effectively convert mechanical energy into electricity.…”