“…The FT-IR spectra of PI and FG@PI particles indicated that after the condensation reflux of xylene, PI has completed the imidization, and the characteristic absorption peaks of the imide groups were presented at approximately 1780 cm −1 , 1720 cm −1 , 1378 cm −1 , and 721 cm −1 in PI and FG@PI particles. 34,35 Finally, it can also be seen that PI and FG@PI particles have the same absorption peak, which suggests that PI coating on the surface of FG does not destroy the chain structure of p I. All the characterizations above confirmed that FG was completely coated by PI.Figure 2.Schematic representation showing the fabrication of PI@FG particles.…”
Section: Resultsmentioning
confidence: 81%
“…Figure 4(a) shows the FTIR spectra of all PI composite film samples. The result shows that the characteristic absorption peaks of imide groups in PI and its composites appear at 1780 cm −1 , 1720 cm −1 , 1378 cm −1 , 721 cm −1 34,35 , the carbonyl groups with wavenumbers of about 1750 cm −1 were also detected. 36 This indicated that when FG@PI particles were introduced into PI matrix as fillers, the main chain structure of PI was not destroyed.…”
Flake graphite @polyimide (FG@PI) particles with core @shell like structure were successfully synthesized and subsequently incorporated into PI matrix to prepare pI/FG@PI composite films. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed that flake graphite (FG) was covered by PI coating and showed a fluffy structure. Thermogravimetric analysis (TGA), FT-IR, and XRD were also used to characterize FG@PI particles. The PI intermediate layer increases interaction between particles and films, which is very beneficial for increasing dielectric constant and inhibiting dielectric loss of pI/FG@PI composite. The experimental result shows that the pI/FG@PI composite film with 50wt% filler loading exhibits a high dielectric constant of 83.5 (about 24 times that of pure PI) and low dielectric loss of 0.11 at 1 MHz. Furthermore, its tensile strength is maintained at 78 MPa. This shows that the structure of PI intermediate layer is very beneficial for preparation of high dielectric constant and low dielectric loss composite.
“…The FT-IR spectra of PI and FG@PI particles indicated that after the condensation reflux of xylene, PI has completed the imidization, and the characteristic absorption peaks of the imide groups were presented at approximately 1780 cm −1 , 1720 cm −1 , 1378 cm −1 , and 721 cm −1 in PI and FG@PI particles. 34,35 Finally, it can also be seen that PI and FG@PI particles have the same absorption peak, which suggests that PI coating on the surface of FG does not destroy the chain structure of p I. All the characterizations above confirmed that FG was completely coated by PI.Figure 2.Schematic representation showing the fabrication of PI@FG particles.…”
Section: Resultsmentioning
confidence: 81%
“…Figure 4(a) shows the FTIR spectra of all PI composite film samples. The result shows that the characteristic absorption peaks of imide groups in PI and its composites appear at 1780 cm −1 , 1720 cm −1 , 1378 cm −1 , 721 cm −1 34,35 , the carbonyl groups with wavenumbers of about 1750 cm −1 were also detected. 36 This indicated that when FG@PI particles were introduced into PI matrix as fillers, the main chain structure of PI was not destroyed.…”
Flake graphite @polyimide (FG@PI) particles with core @shell like structure were successfully synthesized and subsequently incorporated into PI matrix to prepare pI/FG@PI composite films. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed that flake graphite (FG) was covered by PI coating and showed a fluffy structure. Thermogravimetric analysis (TGA), FT-IR, and XRD were also used to characterize FG@PI particles. The PI intermediate layer increases interaction between particles and films, which is very beneficial for increasing dielectric constant and inhibiting dielectric loss of pI/FG@PI composite. The experimental result shows that the pI/FG@PI composite film with 50wt% filler loading exhibits a high dielectric constant of 83.5 (about 24 times that of pure PI) and low dielectric loss of 0.11 at 1 MHz. Furthermore, its tensile strength is maintained at 78 MPa. This shows that the structure of PI intermediate layer is very beneficial for preparation of high dielectric constant and low dielectric loss composite.
“…In addition, the purchased TiO 2 and PVDF were also investigated. The characteristic absorption peaks of the imide groups were presented at approximately 1780 cm −1 , 1720 cm −1 , 1378 cm −1 , and 721 cm −1 in PI and its composites 42,49 ; the carbonyl group with wavenumber of about 1750 cm −1 was also detected. 50,51 In addition, the peak at 1180 cm −1 was enhanced in PI/PVDF composite films, which is due to the C–F bond of PVDF.…”
Section: Resultsmentioning
confidence: 95%
“…For purchased PVDF, the diffraction peaks at 2θ = 17.4, 18.5, 20.3, and 39.1, which corresponded to the (100), (020), (110), and (021) planes of PVDF, respectively; this meets previous reports. 49 For TiO 2 , it is obvious that this is a typical anatase structure. The characteristic peak of PI appeared at 2θ = 19.5.…”
Section: Resultsmentioning
confidence: 99%
“…53 Figure 5 shows that when the loading of filler approach to 40wt%, dielectric constant of PI/TiO 2 nanocomposites reaches its maximum value of ε PI/TiO2 =6.48, which was slightly higher than previous report. 49,54 Figure 5 illustrated loss tangent of PI/TiO 2 nanocomposite films with TiO 2 loading. When TiO 2 loading was close to 50wt%, loss tangent of PI/TiO 2 nanocomposite films reached its maximum of 0.02.…”
A series of three-phase composite films with different filler contents were prepared by in-situ polymerization. The composite films comprise polyimide (PI), poly (vinylidene fluoride) (PVDF), and titanium dioxide (TiO2). Compared with PI/TiO2 composite films, the PI/TiO2-PVDF composite films not only get a significant increase in dielectric constant, but also own better mechanical properties. Our results show that with the loading of 50wt% PVDF particles, the dielectric constant of PI/TiO2-PVDF composite films increased from 6.5 to 18.14 at 1 MHz and room temperature, while the tensile strength of PI/TiO2-PVDF composite films increased from 45 to 72 MPa. In addition, the films maintain a low loss tangent of about 0.02. PI/PVDF composite films were also prepared. It was found that dielectric constant of PI/PVDF composite was significantly lower than that of PI/TiO2-PVDF composite films when the loading of PVDF is 50wt%.
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