Preparation and characterization of polyacrylonitrile doped PVDF/heteropoly acid composite membranes

Guo, Jing; Chen, Yingbo; Kim, Hern

doi:10.1177/0954008312439082

Cited by 9 publications

(4 citation statements)

References 21 publications

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“…The FTIR spectra showed a dramatic reduction in the absorption at 2243 cm À1 (shifted to 2239 cm À1 because of the conjugation effect), coupling with the increase of 1615 cm À1 . These two peaks are assigned to stretching of nitrile group and C¼N, respectively, 28 which indicates that the cyclization occurs extensively. The significant decrease in CH 2 bending signal at 1450 cm À1 and the increase of C¼C stretching signal at 1580 cm À1 confirm that the dehydrogenation happened in a large part of the chain, 29,30 which results in the formation of aromatic ring structure.…”

Section: Resultsmentioning

confidence: 99%

The formation of conjugated structure and its transformation to pseudo-graphite structure during thermal treatment of polyacrylonitrile

Shuai

Gao

et al. 2016

High Performance Polymers

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Three types of polyacrylonitrile (PAN) were considered in order to investigate the effect of molecular composition and configuration on the formation of conjugated structures during stabilization and the conversion of that to pseudo-graphite sheets after carbonization. The stabilization process was performed in an inert or oxidative atmosphere with a temperature ramp from 180°Cto 280°C. The thermal behavior was studied by differential scanning calorimetry, and the change of chemical groups and conjugated structures was detected by in situ measurement of infrared (Fourier transform infrared) and ultraviolet–visible spectroscopy, respectively. The carbonization process of the stabilized samples was performed using a thermogravimetric analyzer under nitrogen atmosphere in the temperature range of 150°C–1200°C, and Raman spectra were applied to study the pseudo-graphite sheets of the residuals. It is suggested that the introduction of comonomer or the improvement of the isotactic regularity of the polymer chain are helpful to promote the stabilization reactions and accelerate the formation of conjugated structures rather than the extent of conjugation during stabilization in nitrogen. Moreover, they are also beneficial to obtain higher degree of graphitization and larger size of the pseudo-graphite sheets with less structural defects after carbonization. While stabilization is performed in air, atactic PAN copolymer has the highest extent of stabilization among these three PAN samples, but they are extremely close. PAN samples with comonomer or higher isotacticity still show a little advantage in the formation speed of the conjugated structures. After carbonization, PAN with higher isotacticity has the highest carbon yield and graphitization degree and the largest size of pseudo-graphite sheets with least structural defects. In addition, the presence of oxygen during stabilization is contributory to increase the extent of stabilization and generate some bigger conjugated structures, which leads to obtain higher graphitization degree and larger size of pseudo-graphite sheets, but it also brings more structural defects.

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Section: Resultsmentioning

confidence: 99%

The formation of conjugated structure and its transformation to pseudo-graphite structure during thermal treatment of polyacrylonitrile

Shuai

Gao

et al. 2016

High Performance Polymers

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“…As shown in figure 1(a), after the pre-oxidation treatment, the stretching vibration peaks of -C≡N (2240 cm −1 ) in nitrogen and air atmospheres were significantly weakened, while the variations of -C=N and -C=C vibration peaks located at 1620 cm −1 and 1580 cm −1 indicated the reaction formation structures significantly increased. It was revealed that cyclization and dehydrogenation [31] occurred in the above two atmospheres. At the same time, C=O peak represented the carboxyl group in the comonomer and appeared at 1730 cm −1 in the PAN copolymer before the pre-oxidation treatment.…”

Section: Conjugated Structures Of Pre-oxidized Pan At Different Ambie...mentioning

confidence: 99%

Effect of ambient atmosphere on the formation and evolution of conjugated structure of pre-oxidized polyacrylonitrile

Wang

Shuai

et al. 2022

Mater. Res. Express

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The ambient atmosphere has the remarkable effect on the chemical reaction mechanism and the formation of characteristic chemical structures and conjugated structures for pre-oxidized PAN. In the present paper, fourier transform infrared spectroscopy (FT-IR) and ultraviolet visible spectroscopy (UV-vis) were used to characterize the variations of chemical reaction characteristic structures and conjugate structures of copolymerized PAN in nitrogen and air atmosphere, respectively. Combined with the multivariate reaction model proposed by the predecessors, it can be found thatthat two main conjugated structures (conjugated polyene and conjugated aromatic heterocycle) formed during the pre-oxidation process of copolymerized PAN . In nitrogen atmosphere, the formed main structure units were the conjugated diene and conjugated double ring with 1-2 double bonds. By contrast, the formed main units in air were the conjugated diene and conjugated tricyclic with a double bond. During the whole pre-oxidation process, the maximum unit numbers of conjugated double bonds and conjugated rings were no more than four and six, respectively. Increasing the heat treatment temperature was easy to form more conjugate structures than prolonging the heat treatment time. Furthermore, with the increase of heat treatment temperature or time in air, the main conjugate unit numbers had no obvious change, while the maximum unit numbers increased slightly. When exposed in nitrogen atmosphere , the main conjugated polycyclic structure was transformed into conjugated tricyclic structure after the heat treatment at 250 oC for more than 3 hours. In addition, when the heat treatment temperature and time were 280 oC for more than 4 hours, the main conjugated polyene structure was transformed into conjugated triene, andthe maximum conjugated unit numbers increased slightly with it.

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“…The strongest peak of the α phase is stated to be 766 cm À1 . [64][65][66][67][68][69][70][71][72][73][74] As a result of all of this, crystalline phase analyses and crystalline phase percentages were investigated in the presented study using FTIR measurements FTIR analyses were conducted for each sample to specify the degree of crystallinity of the β phase content. Figure 8 shows the FTIR spectrum of each electrospun PVDF and PVDF/BaTiO 3 nanofibers.…”

Section: Ftir Analysismentioning

confidence: 99%

Investigation of the optimum vibration energy harvesting performance of electrospun PVDF/BaTiO₃ nanogenerator

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Kasım

Yazıcı

2022

Journal of Composite Materials

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The piezoelectric vibration energy harvesting performance of an electrospun poly(vinylidene fluoride) (PVDF)/Barium Titanate (BaTiO3) nanocomposite piezo polymer nanogenerator was investigated in this study. To obtain the highest piezoelectric output value, electrospinning was performed using four distinct solvent volume ratios of Acetone/Dimethylformamide (DMF) of 0:10, 2:8, 4:6, and 6:4 and three different PVDF weight percent polymer concentrations of 10, 15, and 20. Additionally, three distinct BaTiO3 addition weight percents of 5, 10, and 15 were investigated. The optimal concentration of PVDF (15 wt.%) was combined with a 6:4 volume ratio of Acetone/DMF to form a nanocomposite piezo polymer nanogenerator. The morphology and crystalline structure of PVDF and PVDF/BaTiO3 were analyzed using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) techniques. Nanocomposite piezo polymer nanogenerator was manufactured to harvest energy from vibration. A cantilever beam was developed without a tip mass type system for piezoelectric energy harvesting tests. The highest piezoelectric power output was obtained as 0.243 μW (15 wt.% PVDF and 5 wt.% BaTiO₃), Acetone/DMF (6:4 vol./vol.)) under 10 MΩ at the 15.7 Hz resonance frequency. The morphology of electrospun nanofibers has a significant impact on the piezoelectric performance of a nanocomposite piezo polymer nanogenerator at high-amplitude vibration.

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Preparation and characterization of polyacrylonitrile doped PVDF/heteropoly acid composite membranes

Cited by 9 publications

References 21 publications

The formation of conjugated structure and its transformation to pseudo-graphite structure during thermal treatment of polyacrylonitrile

The formation of conjugated structure and its transformation to pseudo-graphite structure during thermal treatment of polyacrylonitrile

Effect of ambient atmosphere on the formation and evolution of conjugated structure of pre-oxidized polyacrylonitrile

Investigation of the optimum vibration energy harvesting performance of electrospun PVDF/BaTiO₃ nanogenerator

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Preparation and characterization of polyacrylonitrile doped PVDF/heteropoly acid composite membranes

Cited by 9 publications

References 21 publications

The formation of conjugated structure and its transformation to pseudo-graphite structure during thermal treatment of polyacrylonitrile

The formation of conjugated structure and its transformation to pseudo-graphite structure during thermal treatment of polyacrylonitrile

Effect of ambient atmosphere on the formation and evolution of conjugated structure of pre-oxidized polyacrylonitrile

Investigation of the optimum vibration energy harvesting performance of electrospun PVDF/BaTiO3 nanogenerator

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Investigation of the optimum vibration energy harvesting performance of electrospun PVDF/BaTiO₃ nanogenerator