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Zhang, G. Z.; Kitamura, Tomohiko; Yoshida, Hiroyuki; Kawai, Tadashi

doi:10.1023/a:1020628627460

Cited by 18 publications

(11 citation statements)

References 11 publications

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“…FTIR–ATR can give useful information about the polymer structure, foregone studies showed that the vibration bands at 612, 763, 796, 855, 970, 1150, 1214, and 1383 cm −1 correspond to α phase,5–9 whereas vibration bands at 840 and 1278 cm −1 are the character bands of β phase 6, 7, 24. From Figure 4, we can see that the extruded films showed the characteristic spectrum of the α phase with absorption bands at 612, 763, 796, 855, 970, 1149, 1210, and 1383 cm −1 , whereas there are also weak absorption at 840 and 1278 cm −1 , suggesting that there is small amount of β phase in the extruded films.…”

Section: Resultsmentioning

confidence: 98%

“…At least four crystalline phases, α, β, γ, and δ, have been reported in PVDF while the molecular chain conformations of these phases are: trans ‐gauche + ‐ trans ‐gauche − (TG + TG − ) for α and δ phase, all trans (TTTT) for β phase, and T 3 G + T 3 G − for γ phase 2–5. The α phase is a common phase with a TG + TG − molecular chain conformation and can be obtained from melt or solvent casting5–9 and the β phase is the most useful phase, which has aroused more technological interest for providing the piezoelectric and ferroelectric properties. For the excellent piezoelectric and ferroelectric properties, β phase was studied most, the results showed that it can be obtained by transforming from α phase under special conditions such as, mechanical deformation,10, 11 high electric field,12, 13 quenching,14 and through the use of nucleating agents 15.…”

Section: Introductionmentioning

confidence: 99%

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Influence of extrusion, stretching and poling on the structural and piezoelectric properties of poly (vinylidene fluoride‐hexafluoropropylene) copolymer films

Yan

Liu

Yang

et al. 2007

J of Applied Polymer Sci

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Three types of poly (vinylidene fluoridehexafluoropropylene) (PVDF-HFP) copolymer films were prepared by extrusion, stretching as well as simultaneously stretching and static electric field poling (SSSEP), respectively, and measured by the differential scanning calorimetric, wide angle X-ray diffraction, fourier transformation infrared-attenuated total reflection, and Dynamic mechanical analysis. The experimental results showed that the films prepared by stretching and SSSEP have higher crystallinity and b phase than by extrusion. SSSEP improved the chain orientation enormously both in crystalline and amorphous regions, resulting in the highest storage modulus. Because of the lower b phase content, the extruded films exhibited the lowest piezoelectric coefficient d 33 . For the stretched and SSSEP films, although the b phase content was similar, the d 33 was distinct because of the different potential energy for the rotation of the dipoles. In addition, the SSSEP films gave the maximum d 33 (24 pC/N), higher than the other PVDF-HFP copolymer films that have been reported.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Influence of extrusion, stretching and poling on the structural and piezoelectric properties of poly (vinylidene fluoride‐hexafluoropropylene) copolymer films

Yan

Liu

Yang

et al. 2007

J of Applied Polymer Sci

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“…Nylon-66 and nylon-48 are miscible from analysis of crystallization dynamics. 16 Nylon-66 and nylon-48 have the same number of amide groups in the repeating unit, and similar distance between hydrogen bonding along the main chain. The temperature range of the α-β transition for the blend lower than that pure nylon-66 or nylon-48 indicated interactions between nylon-66 and nylon-48 to effect the phase transition.…”

Section: Resultsmentioning

confidence: 99%

“…Simultaneous DSC-XRD plots of nylon-66 and nylon-66/nylon-48 blends were in the same way as nylon-48 in Figure 4. Figure 5 shows φ Nylon-66 dependency of the equilibrium melting temperature (T m 0 ) 16 and α-β transition temperature (T α−β ) obtained by DSC-XRD and DSC-FT-IR for nylon-66/nylon-48 blends. In semicrystalline polymer blends, melting temperature depression is well explained by the interaction parameter (χ 12 ) using Flory-Huggins equation 18,19 or the Nishi-Wang equation.…”

Section: Resultsmentioning

confidence: 99%

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Phase Transition Behavior of Nylon-66, Nylon-48, and Blends

Zhang

Watanabe

Yoshida

et al. 2003

Polym J

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ABSTRACT:Phase transitions, including α-β phase transition and melting, of nylon-66, nylon-48 and blends were measured by simultaneous DSC-XRD and DSC-FT-IR. The molecular mechanism of α-β transition and melting of nylon-66 and blends were estimated from DSC-XRD and DSC-FT-IR. On the broad endothermic peak between 100 and 200• C, spacing of (010/110) of α-form expanded from 0.36 nm to 0.40 nm, and spacing of (100) of α-form changed from 0.44 nm to 0.41 nm, then (100) of β-form appeared. The triclinic ab plane changed to the rhombohodral ab plane from 100 to 200• C. The slide of hydrogen bonded sheet induced transition to the hexagonal β-form. Double melting peaks on DSC heating curve were due to the melting of two types of β-form consisted with weak and strong hydrogen bonded molecules. Nylon-66 is an important semicrystalline polymer. Nylon-66 shows solid-state transition called as the Brill transition, 1 and multiple melting 2-5 on heating from the room temperature to 280 • C. At the Brill transition, the triclinic α-form changes to a pseudohexagonal β-form. The temperature of the Brill transition has been reported variously from 100 to 240 • C, which appears sensitive to crystallization, annealing and deformation of the sample. 2 Many studies on the Brill transition for nylon have been carried out by XRD, NMR, FT-IR, and DSC. 2-9 Multiple melting is commonly observed in the nylon-66 sample crystallized from solution in methanol. 5 Several mechanisms of multiple melting are proposed such as independent melting of polymorphism of nylon-66, melt and re-crystallization of unstable crystallites and reorganization of amorphous parts. The mechanism of transitions is not fully understood owing to the complexity in multiple transitions.Thermal analysis, especially DSC is convenient to observe phase transition, however, DSC gives only total thermodynamic information of samples. Other measurements are necessary to obtain structural information. We have reported that the simultaneous DSC-FT-IR and DSC-XRD methods give not only thermal information but also conformational and structural information on real time of transitions such as crystallization, melting and solid-state transition. [10][11][12] Applications of the simultaneous DSC-FT-IR and DSC-XRD were reported to analyze the mechanism of α-γ transition of † To whom correspondence should be addressed.PVDF. 13,14 In the present work simultaneous DSC-FT-IR and DSC-XRD methods were used to analyze the molecular mechanism of phase transitions of nylon-66, nylon-48 and blends during heating. EXPERIMENTALNylon-66 (Scientific Polymer Products) and nylon-48, prepared using the interface polymerization of chloro octanedioyl and butanediamine, were used in this study. The relative viscosity of nylon-66 and nylon-48 is η rel = 1.79 and 1.90 respectively (measured at 25 • C in m-cresol). Nylon-66 and nylon-48 were dissolved in m-cresol at room temperature. Blend content of nylon-66 (φ Nylon-66 ) was 0-1.0 in weight fraction (φ Nylon-66 = 0.8 indicates blend of composition nylon-4...

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