Accession Number : ADA193581

Title :   Piezoelectric Properties and Temperature Stability of Poly (Vinylidene Fluoride-Trifluoroethylene) Copolymers.

Descriptive Note : Rept. for Jun 85-Jun 86,

Corporate Author : NAVAL RESEARCH LAB ORLANDO FLA UNDERWATER SOUND REFERENCE DIV

Personal Author(s) : Stack, G M ; Ting, R Y

PDF Url : ADA193581

Report Date : 11 Jun 1986

Pagination or Media Count : 10

Abstract : Piezoelectric measurements were made on several copolymers of vinylidene fluoride and trifluoroethylene having a vinylidene fluoride concentration in the range of 65 to 75%. The hydrostatic g constant showed only a slight dependence on pressure, and pressures up to 35 MPa caused no apparent loss of the piezoelectric activity. A significant increase in the value of the hydrostatic g constant occurred with an increase in temperature. Anomalous results obtained upon cooling below room temperature may be attributed to the glass transition temperature of the trifluoroethylene comonomer. Temperature aging studies were performed at high temperatures using films of these copolymers. A significant loss of piezoelectric activity occurred after long time exposure. Isothermal studies at various aging temperatures revealed that this decay continued over a long time span. The aging behaviour characteristically followed a linear dependence on the logarithm of aging time. Keywords: Piezoelectric measurements; Vinylidene fluoride copolymers; Temperature stability.

Descriptors :   *COPOLYMERS, *FLUORIDES, *PIEZOELECTRIC EFFECT, *VINYL PLASTICS, AGING(MATERIALS), ANOMALIES, COOLING, EXPOSURE(GENERAL), GLASS, HIGH TEMPERATURE, ISOTHERMS, LONG RANGE(TIME), LOSSES, MEASUREMENT, PIEZOELECTRIC MATERIALS, POLYMERS, ROOM TEMPERATURE, TEMPERATURE, THERMAL STABILITY, TIME, TIME INTERVALS, TRANSITION TEMPERATURE

Subject Categories : Polymer Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE