Infrared spectra and crystal structures of polyamides

Miyake, Akihisa

doi:10.1002/pol.1960.1204414319

Cited by 122 publications

(57 citation statements)

References 23 publications

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“…A significant change was observed in the 690-580 em -t region. The amide V band (NH out-of-plane vibration) 10 at 687 em -1 and the amide VI band at 584cm-1 were observed in the infrared spectra of 1)(9 and IJ(ll films. On the other hand, in the spectra of y9 and y 11 films, the above two absorptive bands disappeared but a new band appeared at 627 em -1 .…”

Section: Characterization Of Specimensmentioning

confidence: 99%

Dielectric and Piezoelectric Properties of Nylon 9 and Nylon 11

Yano

Soen

1986

Polym J

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ABSTRACT:Various specimens of nylon 9 and nylon II were prepared, and their crystalline structures, the temperature and frequency dependences of electric properties were investigated. Dielectric constants (at 10Hz) of various specimens were about 2.5-3 in the temperature range from -160°C to room temperature, and they began to increase near T 8 and reached above 30 at about 100°C. They showed three dielectric loss peaks due to two types oflocal mode motion and the glass transition. Piezoelectric behavior of the IX form specimen obtained by slow cooling of melts and that of the y form specimen obtained by casting from its trifluoroacetic acid solution were almost the same, but a mixture of IX and y forms obtained by quenching of the melts into liquid nitrogen had a larger piezoelectric constant than the above two. From these results it may be considered that the lower regularity in the dipole orientation within the mixture makes it relatively easier to rearrange the dipoles in parallel to the electric field in the poling process. Nylon 9 had a larger piezoelectric constant than nylon II, which may be due to the higher dipole density of nylon 9. The piezoelectric stress constant of the stretched film was larger than the unstretched one, but the piezoelectric strain constant of both were similar. The largest piezoelectric stress constant of 2.1 mcm-2 (at 25°C) was obtained from a stretched nylon 9 specimen and the largest piezoelectric strain constant of 1.1 pCN _, (at 25oC) was obtained for nylon 9 specimen which was a mixture of IX andy forms.KEY WORDS Odd Nylons I Nylon 9 I Nylon II I Dielectric Property I Piezoelectric Property I Dielectric and piezoelectric properties of polymers are closely related to the chemical and crystalline structure of materials and the dipole density in the crystalline unit cell. The all trans conformation of the odd nylon molecules such as nylon 9 and nylon 11 gives a large dipole moment perpendicular to the chain axis and all dipole moments are aligned to the same direction. So the odd nylons can have a spontaneous polarization in the unit cell of the crystalline phase, and thus the odd nylons are good piezoelectric materials. electric properties of these nylon 11 specimens of o: and y phases have been also reported; 2 -? under equivalent poling conditions, the piezoelectric constants obtained from y structure are higher than that of o: structure. It is proposed that the field-induced dipole alignment might more effectively occur in the y structure than in the ordinary o: structure.It has been reported that nylon 11 has a triclinic o: form and a pseudohexagonal y form. 1 The o: form can be obtained by slowly cooling the melt to room temperature, and the y form by quenching from the melt. 2 • 3 The To the best of our knowledge, no report has been published about the dielectric and piezoelectric properties of nylon 9. According to the method of ref. 4, the dipole density in the crystal phase of nylon 9 is estimated to be higher than that of nylon 11. Therefore nylon 9 may be expected...

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Section: Characterization Of Specimensmentioning

confidence: 99%

Dielectric and Piezoelectric Properties of Nylon 9 and Nylon 11

Yano

Soen

1986

Polym J

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“…[21][22][23][24][25][26][27][28] According to Vasanthan's results, [27][28][29] the absorption bands characteristic of the g phase (973 cm À1 ) and of the a phase (930 cm…”

Section: Resultsmentioning

confidence: 97%

Strong Orientation of Polymer Chains and Small Photochromic Molecules in Polyamide 6 Electrospun Fibers

et al. 2007

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“…hydrogen bonds); moreover it is well known that both polyamides [38] and conductive polymers [39] show a characteristic and strong IR pattern. In Figure 2 the FT-IR spectra of a nonwoven mat of pure PA-6 fibers and of PA-6 þ FeCl 3 are reported.…”

Section: Resultsmentioning

confidence: 99%

Composite Polyamide 6/Polypyrrole Conductive Nanofibers

Granato

Bianco

Bertarelli

et al. 2009

Macromol. Rapid Commun.

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Conductive Polyamide 6 (PA-6) nanofibers were prepared by making a conductive polypyrrole coating obtained by a polymerization of pyrrole molecules directly on the fiber surface. A solution of PA-6 added with ferric chloride in formic acid has been electrospun and the fibers obtained showed an average diameter of 260 nm with a smooth surface. The fibers have been then exposed to pyrrole vapours and a compact coating of polypyrrole was formed on the fiber surface. The growth of the coating was monitored by measuring the increment of the fiber diameter and by FT-IR spectroscopy. The same technique was used to study the interaction between the ferric chloride and the polyamide chains. The polypyrrole coating on the fibers turned out to be conductive with a pure resistive characteristic and the stability of the conductivity was evaluated in air at room temperature.

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Infrared spectra and crystal structures of polyamides

Cited by 122 publications

References 23 publications

Dielectric and Piezoelectric Properties of Nylon 9 and Nylon 11

Dielectric and Piezoelectric Properties of Nylon 9 and Nylon 11

Strong Orientation of Polymer Chains and Small Photochromic Molecules in Polyamide 6 Electrospun Fibers

Composite Polyamide 6/Polypyrrole Conductive Nanofibers

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