Reverse piezoelectric behavior of carbon fiber thermoplastic‐matrix composite

The reverse piezoelectric effect was observed in the through‐thickness direction of a continuous carbon fiber nylon‐6 matrix composite. The piezoelectric coupling coefficient was 2.2 × 10−6 m/V, as determined up to an electric field of 261 V/m. The effect was largely reversible upon turning off the field and was unaffected by field reversal. It is attributed to the electric dipoles in the nylon‐6 matrix.