PIEZOELECTRICITY IN AROMATIC POLYAMIDE THIN-FILMS PREPARED BY VAPOR-DEPOSITION POLYMERIZATION

Thin films of aromatic polyamide were prepared from 4,4'-diamino diphe nyl ether (ODA) and 4,4'-biphenyl dichloride (BPDC) by the vapor depos ition polymerization method. The evaporation temperature of the ODA wa s fixed at 120 degrees C and that of BPDC was varied from 118 degrees C to 128 degrees C. The film was poled by a corona discharge at 250 de grees C for 30 min. The maximum piezoelectric constant e(31) of 0.8 mC /m(2) was obtained at the BPDC evaporation temperature of 124 degrees C. The piezoelectric activity persisted up to 210 degrees C.