The pressure and temperature dependence of piezoelectric and pyroelectric response of poled unoriented phase I poly(vinylidene fluoride)

Abstract

Articles you may be interested inThe poling field and draw dependence of the piezoelectric and pyroelectric response of pressurequenched, phase I poly(vinylidene fluoride) films Some aspects of piezoelectricity and pyroelectricity in uniaxially stretched poly(vinylidene fluoride)The hydrostatic piezoelectric coefficient d p and the pyroelectric coefficient p y of poled unoriented phase I films were measured at pressures up to 7.0 Kbar and at temperatures from -84 to + 48 ·C. The pressure dependence of the glass transition temperature over the same pressure range was also determined. The results obtained for these unoriented films are compared with results obtained previously for oriented films. The effect of the glass transition temperature (Tg) and another transition occurring in the range of pressure and temperature used (T t ) on the piezoelectric and pyroelectric response for both oriented and unoriented films are discussed. At temperatures below T g , P y decreased with increased temperature, while d p showed a shallow maximum so that for both types of response minimum values were obtained at the T g •

Energy harvesting from nanofibers of hybrid organic ferroelectric dabcoHReO4

“…As expected, the current increases with increasing temperature. The corresponding pyroelectric coefficient of the as-spun dacboHReO 4 nanofibers has been found to be about 8.5 lC/m 2 K. This value is comparable with the reported pyroelectric coefficient of a poled PVDF film 32 and KNbO 3 nanowire-polymer composite. 33 In spite of the lower pyroelectric coefficient measured for dabcoHReO 4 nanofibers when compared to bulk crystals (our measurements in single crystal of dabcoHReO 4 grown from aqueous solution of the perrhenate acid and dabco, reveal the pyroelectric coefficient p x of about 46 lC/m 2 K), the fiber mat has a great advantage over single crystals because it is easier to incorporate into electrical devices; it has lower heat capacity and presents a pyroelectric coefficient that is similar to that of the best current alternative candidates.…”

Future prospects and recent developments of polyvinylidene fluoride (PVDF) piezoelectric polymer; fabrication methods, structure, and electro-mechanical properties

“…33 The variation of the pyroelectric constant with poling eld and a comparison of such constants for PVDF was shown by Kenney and Roth. Pyroelectric coefficients have been studied down to low temperatures (6 K) by Glass and Negran, and as a function of pressure by Scheinbeim et al 35 Pyroelectricity in PVDF remains stable for years and is fully reversible with temperature change. 34,35…”

“…Pyroelectric coefficients have been studied down to low temperatures (6 K) by Glass and Negran, and as a function of pressure by Scheinbeim et al 35 Pyroelectricity in PVDF remains stable for years and is fully reversible with temperature change. 34,35…”

The electric moment contribution to the piezoelectricity of PVDF

“…The available literature is contradictory in this respect. Particularly the hydrostatic piezoelectric coefficient is reported irregularly with both signs (undrawn materials: positive sign [25], negative sign [15]; drawn materials: positive sign [2,, negative sign [20,. The troubles may arise from an irregular definition of the sign of the hydrostatic piezoelectric coefficient (see above, and the definition of dh distinct from d p ) .…”

“…It is the aim of the present paper to investigate, by this means, the contribution of the dielectric properties to the hydrostatic piezoelectricity of PVDF/PMMA blends. This material is advantageous for this purpose since the hydrostatic piezoelectric coefficients d p of PVDF/PMMA mixtures have already been determined, and have been shown to depend strongly on pressure [9,15]. Blending with PMMA, as already mentioned, additionally allows variation of the supermolecular structure to a wide extent.…”