Piezoelectricity in nylon 5,7

The authors have investigated nylon 5,7 as a piezoelectric polymer which can potentially exhibit very high activity. Nylon 5,7 is synthesized using improved procedures, and the product polymer is characterised by X-ray diffraction, calorimetry, and the thermally stimulated current. Films are prepared by quenching from the melt. The piezoelectric response is compared to that of other polyamides. Initial measurements a field strength of 175 kV/cm resulted in a piezoelectric strain coefficient d₃₁=0.4 pC/N. By comparison, d₃₁ values in the literature for nylon 11 and nylon 9 at 400 kV/cm are 0.6 and 1.1 pC/N, respectively (film-forming conditions, poling time, and temperature being the same). This indicates that at an equivalent field strength, nylon 5,7 could surpass the piezoelectric activity of nylon 9 and verify the theoretical prediction of increased activity in the lower odd nylons