Dielectric and Piezoelectric Properties of Nylon 9 and Nylon 11

Abstract

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...

Structure of a Cyclic Trimer as a Model of Nylon 11. Folding at Lamellar Surfaces

“…[3][4][5][6][7][8][9][10][11][12][13] Only in some cases a value close to that expected for the trimer derived model is found. In most cases the d 001 spacing is smaller, in the range 11.2-11.6 Å, which indicates that the hydrogenbonded sheets are shifted by a larger amount than in Figure 4c.…”

“…-503(4) 3000 (3) 296 (1) 28(1) C (11) 11733 (5) 5340 (4) 3477 (1) 22(1) C (10) 11955 (5) 6635 (4) 3769 (1) 26(1) C (9) 14257 (6) 6450 (4) 4022 (1) 26(1) C (8) 14484 (5) 7785 (4) 4311 (1) 26(1) C (7) 16784 (5) 7608 (4) 4568 (1) 24(1) C (6) 17146 (5) 9010 (4) 4844 (1) 27(1) C (5) 17419 (5) 10768 (4) 4691 (1) 24 (1) …”

Piezoelectricity in PANI filled Nylon 11

“…Similarly, G Wu et.al. [9] reported that under equivalent poling conditions Nylon 11 exhibits a larger piezoelectric response for the melt quenched specimen consisting of the mixture of α and γ forms than the pure α and γ forms.…”

“…Mathur et al [8] reported that the piezoelectric strain and stress coefficients (d 31 and e 31 ) showed hysteresis behaviour, when uniaxially oriented Nylon 11 films were polarized under a series of positive and negative poling fields. G Wu et al [9] studied the piezoelectric response of poled Nylon 9 and Nylon 11 films and observed that Nylon 11 exhibits relatively large piezoelectric response, especially when the temperature was elevated above the glass transition temperature.…”

“…Many researchers have [1][2][3][4][5][6][7][8][9][10] studied the piezoelectric properties using thin films prepared by solution casting. However an attempt has been made to study the variation in piezoelectric response of conducting polymer filled Nylon 11 samples with respect to pure Nylon 11.…”