POLYMER DEGRADATION AND STABILITY
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2021
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IF 5.03
Yongqiang Guo,Chao Liu,Hongpeng Liu,Wenjing Wang,Hongbin Li,Chunhua Zhang
This study aims to explore the effects of gamma rays on various properties of poly(1,1-difluoroethylene) (PVDF) membranes under different irradiation conditions. The effects of 60 Co γ-ray irradiation on the hydrophilicity, permeability, and mechanical performances of the PVDF membranes were discussed. Results showed that the size of the radiation dose rate had almost no effect on the performance of the membranes, as determined by the total radiation dose. The fracture and collapse of the PVDF structure under anaerobic conditions were obviously lower than those under aerobic conditions. Advanced characterization methods confirmed that the initial impact of gamma rays on the PVDF membranes occurred between 50 and 200 kGy. When the total dose exceeded 200 kGy, structural collapse and chain scission caused by the oxidative degradation mechanism became widespread, thereby leading to the relaxation of the PVDF network and the decline in properties. This study provides valuable information for the application of PVDF membranes to radioactive wastewater and clarifies the mechanism of membrane irradiation degradation to help prolong the service life of membranes. In addition, low total irradiation dose can embellish polymers and thus provide a feasible method for modifying and grafting polymer membranes in the future.
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高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2019
·
IF 2.781
Wenfeng Han,Haili Wang,Bing Liu,Xiliang Li,Haodong Tang,Ying Li,Huazhang Liu
With Al(NO 3 ) 3 ·9H 2 O as the Al precursor and PVDF as the fluorine source, freestanding AlF 3 sub-microspheres were fabricated following calcination , without the involvement of corrosive HF solution. With the varying of Al(NO 3 ) 3 ·9H 2 O to PVDF weight ratio, θ -AlF 3 and β -AlF 3 , α -AlF 3 were obtained respectively. The formation mechanism, morphology, surface properties and catalytic activities for the dehydrofluorination of 1,1,1,2-tetrafluoroethane to trifluoroethylene were investigated. During the fabrication process, Al(NO 3 ) 3 interacts with O=C bond in DMF. Meanwhile, DMF further interacts with CH 2 species in PVDF. Following calcination , PVDF decomposes to CO 2 and HF fluorinating Al species to AlF 3 . The growth of AlF 3 crystal and particle are confined by PVDF. Consequently, θ -AlF 3 , β -AlF 3 and α -AlF 3 are achieved. At 450 °C, HFC-134a conversion of 23% and reaction rate of 1.9 mmol g −1 h −1 are approached over θ -AlF 3 catalyst. The reaction rate is almost 3 times higher than that of β -AlF 3 and is 40% higher than that of high surface area α -AlF 3 prepared by sol-gel method. No significant deactivation is observed in time on stream of 40 h. The stability is attributed to the interaction of AlF 3 with carbon frame work. The present study provides a scalable and facile synthesis route for AlF 3 spheres with controllable phase structures.
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高影响因子
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
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2018
·Vol. 23
·期 1
·269-276
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IF 2.509
Wang Zenghao,Xie Yongshuai,Xu Chonghe,Shi Shuying,Wang Lin,Zhang Guanghui,Wang Xinqiang,Zhu Luyi,Xu Dong
Lithium-ion batteries have been receiving more and more attention because of the energy crisis. As an important subassembly of lithium-ion batteries, the separator greatly affects the safety of the batteries. Herein, we report for the first time, a novel method fabricated separator by mixing zirconia fibers with polyvinylidene fluoride (PVDF) via papermaking process. The separators possess abundant pores and uniform structure after the phase inversion process. The separator properties were systematically studied at different proportion of PVDF. We find that when the content of PVDF is 40%, the separator has high porosity (77.69%), high electrolyte uptake (523.3%), and excellent thermal stability (thermal shrinkage ratio is 0% at 500 °C). In addition, the rate capability, cycle performance, and ionic conductivity are also investigated. We anticipate that the papermaking method of zirconia fibers will provide a strategy to fabricate a promising separator for enhanced electrochemical performance and high safety of lithium-ion batteries.
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高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2019
·Vol. 30
·期 15
·14007-14021
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IF 2.195
Ahmed Arsalan,Jia Yunming,Huang Yi,Khoso Nazakat Ali,Deb Hridam,Fan Qinguo,Shao Jianzhong
We developed a high-performance electrically conductive and transparent PVDF-TrFE based electrode for piezoelectric pressures sensor using the electrospinning technique. The electrode was produced by depositing the reduced graphene oxide (rGO), multiwall carbon nanotubes (rGO-MCNTs) via spray coating. Various concentration of rGO and MCNTs were used and optimized for improved electrical performance of the resultant electrode. The deposition of poly (3,4-ethylenedioxythiophene) (PEDOT) was successfully achieved by using vapor phase polymerization (VPP). The morphological characteristics of the as-prepared hybrid composite nanofiber mats were analyzed by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (X-RD), and UV–visible spectroscopy. The electrical performance of the fabricated composite nanofibers was measured by using a four-point probe device. The results showed significant enhancement in electrical conductivity of the hybrid nanocomposite which increased up to 3916 S cm −1 and sensitivity of the developed pressure sensor was achieved 67.4 kPa −1 . This work suggests that the hybrid nanocomposite can be used for the transparent electrodes in a piezoelectric pressure sensor.
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高影响因子
MATERIALS & DESIGN
·
2019
·
IF 5.77
Zhen Zhang,Ming Cao,Peng Chen,Bin Yang,Bin Wu,Jibin Miao,Ru Xia,Jiasheng Qian
In this study, selective distribution of amino-functionalized multi-walled carbon nanotubes (MWCNTs-NH 2 ) in poly (vinylidene fluoride)/polyamide 6 (PA6/PVDF) blends is achieved via the mixing process and subsequent migration. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selective extraction confirmed that MWCNTs-NH 2 could migrate from the PVDF phase to the two-phase interface. The composites could significantly improve thermal/electrical conduction capacity of the composites with low dose. The thermal infrared characterization also indicated that the composites have better heat absorption capability and dissipation performance due to the good thermal conductivity . Rheological measurements exhibited the MWCNTs-NH 2 could form network structure with a low content at the interface of the composites. Moreover, the addition of MWCNTs-NH 2 led to an improvement in the mechanical properties compared with the pure PA6/PVDF blends. These results manifest that the thermal/electrical conductivity and mechanical performance of the composites with low filler loading can be significantly improved by selective distribution of MWCNTs-NH 2 through controlling the migration process.
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高影响因子
POLYMER
·
2018
·
IF 3.483
Hongde Lei,Lu Liu,Lukuan Huang,Weixing Li,Weihong Xing
In this study, we fabricated a novel anti-fouling poly(vinylidene fluoride) (PVDF) membrane using a novel amphiphilic copolymer of PVDF grafted with tetrahydrofurfuryl methacrylate (PVDF-g-THFMA). This copolymer was synthesized via photoinduced Cu(II)-mediated reversible deactivation radical polymerization . The amphiphilic copolymer was characterized by 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy . The morphology of the copolymer was examined using scanning electron microscopy. The permeability and hydrophilicity of the membranes were evaluated on the basis of their pure water flux and dynamic contact angles, respectively. The anti-fouling property of the membranes was evaluated by carrying out filtration using a bovine serum albumin (BSA) solution. The PVDF-g-THFMA copolymer membranes showed a pure flux of up to 293.9 L m −2 h −1 bar −1 and a molecular weight cut off of 39.5 kDa. After the filtration of the BSA solution, the PVDF-g-THFMA copolymer membrane was washed with deionized water and the recovery ratio of the pure water flux reached a value of 89.1%. The modified membrane showed good filtration performance and anti-fouling property.
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高影响因子
COLLOID AND POLYMER SCIENCE
·
2013
·Vol. 291
·期 7
·1573-1580
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IF 2.161
Zhao Xuejuan,Zhang Jun,Chen Shuangjun,Wang Xiaolin,Wang Jianxin
The in situ polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA) in poly(vinylidene fluoride) (PVDF) solution was carried out to prepare hydrophilic PVDF/PPEGMA blends. Based on T
g data, the system displayed some miscibility at low PPEGMA content because there were some interactions between PVDF and PPEGMA, as illustrated by Fourier transform infrared spectroscopy analysis, while the miscibility disappeared at high PPEGMA content. The β phase was the predominant crystalline phase of PVDF in the in situ blends, which was independent on PPEGMA content. However, the addition of PPEGMA could change the unit cell structure in the direction of the a -axis of β phase. The degree of crystallinity of the in situ blends calculated by wide-angle X-ray diffraction and differential scanning calorimetry displayed different tendencies with PPEGMA content. The scanning electron microscopy showed that the “spherulites” size increased with the increase in PPEGMA content, since the “spherulites” were comprised of not only crystalline PVDF but also amorphous PVDF and PPEGMA. In addition, the in situ blend had a great improvement in the hydrophilicity; specifically, its water contact angle was down to 26° when the PPEGMA content only increased to 26.9 wt.%.
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高影响因子
FIBERS AND POLYMERS
·
2015
·Vol. 16
·期 10
·2130-2134
·
IF 0.881
Chen Yingbo,Wang Biao,Zhang Shifeng,Hu Xiaoyu,Cheng Bowen,Liu Dongqing,Zhang Yufeng
Cu-BTC/PVDF composite membranes were prepared by immersing PVDF hollow fiber supporting membranes into copper acetate aqueous solution and trimesic acid ethanol solution repeatedly. Surface and cross sectional morphologies of Cu-BTC crystals on the supporting PVDF membrane were investigated using SEM. Chemical composition and crystal structure of Cu-BTC were characterized by IR and XRD. Gas permeance and separation factor for CO 2 and N 2 of the Cu- BTC/PVDF composite membrane were recorded under different pressures. The results illustrated that with increasing reaction times, the crystal layer became more in density and less in defects, resulting in decrease of gas permeance and the separation mechanism changing from convective flow to Knusen diffusion.
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高影响因子
Desalination and Water Treatment
·
2024
·
IF 1
Shuyi Chen,Noor Khatoon,Chen Zhang,Qi Zhang,Shuhong Jiang,Honghai Yang,Jun Wang
Selective recovery of recyclables is a major challenge when treating textile wastewater. For this reason, there is an urgent need to develop nanofiltration membranes with high permeability and selective filtration. In response, a novel composite PVDF loose nanofiltration membrane was developed by combining two different mixed amines system/dopamine (DA) followed by interfacial polymerization with benzoyl chloride (TMC). The two different amines systems were a mixture of GAZ and PEI and a mixture of PIP and PEI, respectively. The effects of GAZ/PEI and PIP/PEI on the microstructure was characterized by SEM, AFM, FTIR and XPS and performance of the membrane was also investigated. The effects of GAZ/PEI and PIP/PEI on the microstructure and the selective layer of membranes were different. The results stated that with the increase of GAZ/PEI the thickness of the selective layer, surface roughness decreased, while the fluxes of pure water and dye wastewater increased. However, with increasing PIP/PEI, surface nodules and roughness both increased. Contrarily, the thickness of the selective layer and PEG800 rejection first decreased and then increased, while the flux of pure water and the dye wastewater first increased and then decreased. The optimal GAZ/PEI and PIP/PEI were 9/91 and 50/50, respectively. When the GAZ/PEI was 9/91, the pure water flux and the RB5 wastewater flux were 20.7 L∙(m 2 ∙h) −1 and 11.5 L∙(m 2 ∙h) −1 . The dye (RB5) retention rate was 94.3% and salt retention rate was 2.1%. However, when the PIP/PEI was 50/50, the pure water flux and RB5 wastewater flux were 26.6 L∙(m 2 ∙h) −1 and 17.1 L∙(m 2 ∙h) −1 increased by 87.3% and 134.2% respectively. The retention rates of RB5 and NaCl were 96.3% and 1.7%. The above results indicate that the composite PVDF LNF membranes prepared with mixed amine monomers instead of single amine monomers have good selective filtration performance.
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高影响因子
Surfaces and Interfaces
·
2024
·
IF 5.7
Xiaojia Zhao,Junjie Fu,Fangqian Yin,Chaoqun Li,Yuyang Xu,Guirong Peng
A one-step co-deposition method based on dopamine and hydrophilic hydroxyethyl methacrylate (HEMA) was proposed for the modification of polyvinylidene fluoride (PVDF) membrane, which could ameliorate its oil-water separation performances and hydrophilicity. A range of modified membranes were prepared by adding different content of HEMA in the reaction solution. For the improved membrane, the minimum water contact angle can reach 13.63°, and the maximum underwater oil contact angle can reach about 150°. The pure water flux for the improved membrane reaches 9668 L·m -2 ·h -1 ·bar -1 , showing excellent hydrophilicity. In addition, the separation efficiency of the improved membrane for a variety of oil-water emulsions exceeds 98%, indicating good permeability and circulating oil resistance. At the same time, this approach is also applicable to other membranes on account of the extensive availability of dopamine.
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高影响因子
Nanoscale
·
2024
·
IF 5.8
Haitao Li,Yingying Zhang,Han Dai,Veronica Pereir,Junfeng Zhao,Hiang Kwee Lee
Polyvinylidene fluoride (PVDF)-based piezoelectric catalysts show promise in mechanical force-driven catalysis due to their good biocompatibility, flexibility, and ease of fabrication. However, the catalytic activity of pristine PVDF is limited due to its low piezoelectric phase content (<20%), poor orientation, and low surface carrier concentration. Here, we introduce an efficient PVDF-based composite nano-catalyst (rGO/PVDF) with high piezoelectric catalytic performance. We achieve this by employing a composite strategy that combines nanoscale water-induced polarization with polar functional group-modified graphene (rGO) serving as a nanoelectrode. The nanoscale water polarization effect, together with the two-dimensional planar structure of PVDF and the modified graphene's polar functional groups, effectively induces orientation in the PVDF piezoelectric phase to increase the functional β phase content. As a result, the β phase content and crystallinity of rGO/PVDF reach 95% and 40%, respectively, which are 600% and 170% higher compared to those of pristine PVDF. This enhancement plays a crucial role in endowing the material with strong force-to-electricity conversion characteristics. Additionally, the surface-modified rGO also boosts PVDF's surface carrier concentration and provides active sites for catalysis on the rGO/PVDF composite. Notably, under optimized conditions, our catalyst achieves a ∼99.1% degradation rate of organic pollutants (10 mg L−1) after 12 minutes of sonication at 240 W and maintains a high efficiency of ∼93.7% even at a 10 times higher pollutant concentration (100 mg L−1). Our piezoelectric catalyst also demonstrates efficient H2O2 production at 95.8 mmol grGO−1 h−1, which is ∼9-fold and ∼134-fold higher than those of untreated PVDF and previously reported PVDF-based piezoelectric catalysts, respectively. This work paves the way for the development of highly efficient PVDF-based piezoelectric catalysts, thereby offering valuable insights for the advancement of mechanically driven catalysis in the environmental, energy, and chemical sectors.
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PubMed
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2024
·
IF 8.4
Jinli Zhao,Juan Li,Qingbai Chen,Mengwei Yang,Yongkang Li,Hong Li,Yuzhong Zhang,Jianyou Wang
The influence of crystallization behavior on membrane structure and performance has been extensively studied in many membrane fields. Some studies of proton exchange membranes used in fuel cells have involved the influence of crystallization. However, crystallization of ion exchange membranes (IEMs) used in electrodialysis (ED) has been rarely studied. Co-ion leakage in ED process is adverse, but there have been few mechanism studies regarding how co-ions cross IEM surfaces on the concentration chamber side and migrate into the dilution chamber to reduce current efficiency. Polyvinylidene fluoride is a kind of good crystalline material. In this study, sodium dodecyl benzene sulfonate was introduced as the functional material , with polyvinylpyrrolidone (PVP) as the hydrophilizing agent. They were blended to prepare cation exchange membranes (CEMs). Amorphous PVP was used to regulate membrane crystallization behavior. The results showed that, when the ion exchange capacity is basically equal, surface roughness of the prepared crystalline CEMs was low and the structure dense. The ED efficiency significantly surpassed amorphous CEMs. The co-ion leakage of amorphous CEMs was greater than those of crystalline CEMs due to the rough and non-dense surfaces of amorphous CEMs. However, after densification modification, although surface resistance increased, co-ion leakage was effectively suppressed. Combining simulation and theoretical analysis, it was presumed that dense membrane surfaces on the concentrated chamber side was very important for suppressing co-ion leakage. This study on the influence and mechanism of crystallinity and co-ion leakage was helpful for optimizing CEM mass transfer and improving current efficiency.
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高影响因子
危险品化学品经营许可证（带存储）