The diffuse behavior of the ferroelectric transition in poly(vinylidene fluoride‐trifluoroethylene) copolymers

Moreira, R. L.; Lobo, R. P. S. M.; Medeiros‐Ribeiro, G.; Rodrigues, Wagner Nunes

doi:10.1002/polb.1994.090320518

Cited by 19 publications

(8 citation statements)

References 23 publications

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“…The low temperature peak is attributed to the well-known ferroelectric-to-paraelectric phase transition of pristine P(VDF-TrFE) copolymer. 20 The higher temperature peak is attributed to the melting phase transition of the P(VDF-TrFE) crystalline portion. Comparing the DSC curves of pristine P(VDF-TrFE) and the P(VDF-TrFE)/ZrO 2 -MMA nanocomposites with 1 wt% of ZrO 2 , we see a decrease in the melting temperature (T M ), from 160.2ºC to 155.3°C, respectively, while almost no change is observed for T C , which changes from 63.2 to 63.3°C.…”

Section: Composite Characterizationmentioning

confidence: 99%

P(VDF-TrFE)/ZrO2 Polymer-Composites for X-ray Shielding

et al. 2016

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Poly(vinylidene fluoride -tryfluorethylene) [P(VDF-TrFE)] copolymers were mixed with zirconia nanoparticles. The investigation was conducted with the intention to produce nanocompounds with potential to be used as protective patient shielding in radiological procedures. Polymer based nanocomposites with 1, 2, 3, 5 and 10 wt% of ZrO 2 nanoparticles were prepared using sol-gel route with zirconium butoxide as the precursor for zirconium oxide nanoclusters. UV-Vis and FTIR spectrometry and differential scanning calorimetry (DSC) were used to characterize the composite samples. We observed a more homogeneous distribution of ZrO 2 nanoparticles encapsulated by methyl methacrylate (MMA) into the polymeric matrix, when compared to composites made without the use of surface modifiers from methacrylate group. Apparently, this property is related to the absence of the strong MMA absorption band at 1745 cm -1 , attributed to C=O bond, in the P(VDF-TrFE)/ZrO 2 -MMA nanocomposites. The radiation damage due to high dose exposuring was performed for gamma doses ranging from 100 kGy to 1,000 kGy. The radiation shielding characterization conducted using x-rays with effective energy of 40 keV has demonstrated that composites with 10% of ZrO 2, and only 1.0 mm thick, can attenuate 60% of the x-rays beam.

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Section: Composite Characterizationmentioning

confidence: 99%

P(VDF-TrFE)/ZrO2 Polymer-Composites for X-ray Shielding

et al. 2016

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“…entropy jump in the ferroelectric Langmuir-Blodgett films, published reports place the entropy jump for the copolymers in the range 0.6R to 0.9R [5,7,8].…”

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confidence: 99%

Ducharme and Fridkin Reply:

Ducharme

Fridkin

2002

Phys. Rev. Lett.

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Ducharme and Fridkin Reply:We have carefully reviewed the Comment by Moreira [1] concerning our Letter [2] reporting measurements of the intrinsic coercive field in ferroelectric Langmuir-Blodgett (LB) films of the random copolymer consisting of 70% vinylidene fluoride and 30% trifluoroethylene, P(VDF-TrFE 70:30). Moriera questions the main conclusion of the Letter, that we have measured the intrinsic coercive field of this material, citing apparent inconsistencies in the analysis. Here we allay these questions by reiterating the complete evidence and by refuting the "physical constraints" proposed by Moriera.The evidence cited in both abstract and summary of the Letter consisted of three parts that must be considered together: (i) agreement with quantitative predictions of the Landau-Ginsburg-Devonshire (LGD) formalism; (ii) confirmation of the expected temperature dependence; and (iii) confirmation of the expected thickness dependence. As stated clearly in the Letter, the magnitude and temperature dependence of the intrinsic coercive field can be estimated from general principles independent of the choice of state model (for further discussion of this point, see Ref.[3]). Further, the temperature and thickness dependences are essential evidence that nucleation and domain growth mechanisms are not limiting the coercive field. Therefore the main conclusion was well supported by much more than numerical agreement with the LGD predictions.The physical constraints proposed by Moriera are incorrect. The first proposal is that the spontaneous polarization cannot exceed the dipole density, which is estimated to be approximately 0.

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“…P(VDF-TrFE) copolymers are ferroelectric materials that undergo a high temperature FE-PE PT with diffuse character [17][18][19]22]. Once the transition temperatures and thermal hystereses decrease with TrFE amount in the copolymer, samples with higher TrFE contents Downloaded by [134.117.…”

Section: Resultsmentioning

confidence: 99%

Electrocaloric Effect in γ-Irradiated P(VDF-TrFE) Copolymers with Relaxor Features

Moreira

2013

Ferroelectrics

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BrazilRelaxor features were induced in P(VDF-TrFE) copolymers by γ radiation. The electrocaloric parameters of virgin and irradiated samples were evaluated, showing close maxima values, though a higher polarizing electric field was required by the irradiated sample. Isothermal entropy change, adiabatic temperature change and refrigerant capacities of S ≈ 22.5 J/kgK, T ≈ 6 K and RC ≈ 130 J/kg, were obtained, just above the Curie transition. For the γ -irradiated sample, the main advantage is the lowering of the working temperature range, circa 15 • C closer to room temperature, which can be beneficial for technical applications in electrocaloric coolers.

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The diffuse behavior of the ferroelectric transition in poly(vinylidene fluoride‐trifluoroethylene) copolymers

Cited by 19 publications

References 23 publications

P(VDF-TrFE)/ZrO2 Polymer-Composites for X-ray Shielding

P(VDF-TrFE)/ZrO2 Polymer-Composites for X-ray Shielding

Ducharme and Fridkin Reply:

Electrocaloric Effect in γ-Irradiated P(VDF-TrFE) Copolymers with Relaxor Features

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