Polyvinylidene fluoride(PVDF)/polyurethane(PU)composite nanofiber membranes were prepared by mixing PVDF and PU at different mass ratios.The microstructure and the crystal structure of the composite nanofiber membrane...Polyvinylidene fluoride(PVDF)/polyurethane(PU)composite nanofiber membranes were prepared by mixing PVDF and PU at different mass ratios.The microstructure and the crystal structure of the composite nanofiber membranes were analyzed by scanning electron microscopy(SEM),Fourier transform infrared(FTIR)spectroscopy and X-ray diffraction(XRD).The hydrophilicity,mechanical properties and piezoelectric properties were also tested.Results showed that when the mass ratio of PVDF to PU was 9∶1,the fiber membrane had the best microstructure,and the crystal form of PVDF changed fromαcrystal toβcrystal in the electrospinning.The addition of PU improved the hydrophilicity,mechanical properties,and piezoelectric signal of the fiber membrane.When the mass ratio of PVDF to PU was 9∶1,the tensile strength reached the peak value of(10.39±0.41)N,and the output voltage reached the maximum value of(1.98±0.12)V.展开更多
The polyvinylidene fluoride(PVDF)nanofiber web by electrospinning technology has the characteristics of fast response,high sensitivity,wide range of pressure,etc.,and provides new sensitive materials for the sensor te...The polyvinylidene fluoride(PVDF)nanofiber web by electrospinning technology has the characteristics of fast response,high sensitivity,wide range of pressure,etc.,and provides new sensitive materials for the sensor testing the dynamic pressure such as foot pressure during walking.Because of the nanofiber mesh structure,it must be packaged to collect piezoelectric charge and bear strong mechanical behavior before industrial practice.The PVDF nanofiber web is usually packaged by incorporating a pair of flexible electrode as well as the lead of signal output.This present work will introduce the detailed packaging process and technology of PVDF nanofiber web,and three different types of packaging electrode materials(adhesive copper foil tape,indium tin oxide(ITO)thin plate,and adhesive conductive cloth)in previously published literatures are compared by the piezoelectric response of their sensor prototypes to a periodic mechanical activation.The results showed that the surface property of packaging material had a significant effect on the piezoelectric response of sensor by PVDF nanofiber web.For PVDF nanofiber web sensor,therefore,it needed a deep investigation on the specific packaging technology in terms of different working conditions.展开更多
A new ion exchange membrane based on polyvinylidene fluoride (PVDF) and sulfonated poly(styrene-divinylbenzene) was prepared by in-situ polymerization. The incorporation of sulfonic groups into the polyvinylidene fluo...A new ion exchange membrane based on polyvinylidene fluoride (PVDF) and sulfonated poly(styrene-divinylbenzene) was prepared by in-situ polymerization. The incorporation of sulfonic groups into the polyvinylidene fluoride composite membrane was confirmed by infrared spectroscopy (IR), ion exchange capacity (IEC) and energy dispersive X-ray analysis (EDAX). Area resistance, IEC and water uptake of the treated membrane were evaluated. When 20% of the crosslinked membrane was sulfonated at 80degreesC for 22 h, the PVDF ion exchange membrane can attain 0.8 Omega . cm(2) area resistance in NaCl aqueous solution at 25degreesC, IEC is as high as 2.43 millimoles per grain of the wet membrane. The hydrophilicity of PVDF membrane is also significantly improved after treatment. When 60% of crosslinked membrane was sulfonated at 80degreesC for 6 h, water uptake of the treated membrane can attain 64.7%.展开更多
Two different morphologies of ZnO（lotus-shaped, rod-shaped） and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy（SEM） a...Two different morphologies of ZnO（lotus-shaped, rod-shaped） and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. Fourier transform infrared spectroscopy（FT-IR）, thermal gravimetry（TG）, and X-ray diffraction（XRD） were also used to characterize the chemical structures and phase composites of ZnO and ZnO/PVDF composite materials. Breakdown voltage, dielectric constant and dielectric loss of ZnO/PVDF composite materials were also tested. Microstructure analysis showed that ZnO nanoparticles dispersed uniformly in the matrix. And the dielectric constant expresses a significantly improvement while the dielectric loss and breakdown voltage expresses no significant change. Moreover, dielectric constant keeps an improvement tendency with increasing content of ZnO.展开更多
Arm symmetrical PbS dendrite （ASD-PbS） nanostructures can be prepared on a large scale by a solvothermal process. The ASD-PbSs exhibit a three-dimensional symmetrical structure, and each dendrite grows multiple bran...Arm symmetrical PbS dendrite （ASD-PbS） nanostructures can be prepared on a large scale by a solvothermal process. The ASD-PbSs exhibit a three-dimensional symmetrical structure, and each dendrite grows multiple branches on the main trunk. Such unique ASD-PbSs can be combined with polyvinylidene fluoride （PVDF） to prepare a composite material with enhanced dielectric and microwave-absorption properties. A detailed investigation of the dependence of the dielectric properties on the frequency and temperature shows that the ASD-PbS/PVDF composite has an ultrahigh dielectric constant and a low percolation threshold. The dielectric permittivity is as high as 1,548 when the concentration of the ASD-PbS filler reaches 13.79 vol.% at 102 Hz, which is 150 times larger than that of pure PVDF, while the composite is as flexible as pure PVDF. Furthermore, the maximum reflection loss can reach -36.69 dB at 16.16 GHz with a filler content of only 2 wt.%, which indicates excellent microwave absorption. The loss mechanism is also elucidated. The present work demonstrates that the addition of metal sulfide microcrystals to polymer matrix composites provides a useful method for improving the dielectric and microwave-absorption properties.展开更多
基金Natural Science Foundation of Jiangsu Province,China(No.BK20190927)Postdoctoral Daily Program of Jiangsu Province,China(No.2019Z104)+2 种基金Natural Science Research Project of Xinglin College of Nantong University,China(No.2016K123)Student Innovation Training Project of Nantong University,China(No.2019111)Nantong University Scientific Research Fund,China(No.17R19)
文摘Polyvinylidene fluoride(PVDF)/polyurethane(PU)composite nanofiber membranes were prepared by mixing PVDF and PU at different mass ratios.The microstructure and the crystal structure of the composite nanofiber membranes were analyzed by scanning electron microscopy(SEM),Fourier transform infrared(FTIR)spectroscopy and X-ray diffraction(XRD).The hydrophilicity,mechanical properties and piezoelectric properties were also tested.Results showed that when the mass ratio of PVDF to PU was 9∶1,the fiber membrane had the best microstructure,and the crystal form of PVDF changed fromαcrystal toβcrystal in the electrospinning.The addition of PU improved the hydrophilicity,mechanical properties,and piezoelectric signal of the fiber membrane.When the mass ratio of PVDF to PU was 9∶1,the tensile strength reached the peak value of(10.39±0.41)N,and the output voltage reached the maximum value of(1.98±0.12)V.
基金“111 Project”Biomedical Textile Materials Science and Technology,China(No.B07024)National Natural Science Foundation of China(No.51405079)+2 种基金China Postdoctoral Science Foundation(No.2015M570307)the Fundamental Research Funds for the Central Universities,Chinathe Jiangsu Planned Projects for Postdoctoral Research Funds,China
文摘The polyvinylidene fluoride(PVDF)nanofiber web by electrospinning technology has the characteristics of fast response,high sensitivity,wide range of pressure,etc.,and provides new sensitive materials for the sensor testing the dynamic pressure such as foot pressure during walking.Because of the nanofiber mesh structure,it must be packaged to collect piezoelectric charge and bear strong mechanical behavior before industrial practice.The PVDF nanofiber web is usually packaged by incorporating a pair of flexible electrode as well as the lead of signal output.This present work will introduce the detailed packaging process and technology of PVDF nanofiber web,and three different types of packaging electrode materials(adhesive copper foil tape,indium tin oxide(ITO)thin plate,and adhesive conductive cloth)in previously published literatures are compared by the piezoelectric response of their sensor prototypes to a periodic mechanical activation.The results showed that the surface property of packaging material had a significant effect on the piezoelectric response of sensor by PVDF nanofiber web.For PVDF nanofiber web sensor,therefore,it needed a deep investigation on the specific packaging technology in terms of different working conditions.
文摘A new ion exchange membrane based on polyvinylidene fluoride (PVDF) and sulfonated poly(styrene-divinylbenzene) was prepared by in-situ polymerization. The incorporation of sulfonic groups into the polyvinylidene fluoride composite membrane was confirmed by infrared spectroscopy (IR), ion exchange capacity (IEC) and energy dispersive X-ray analysis (EDAX). Area resistance, IEC and water uptake of the treated membrane were evaluated. When 20% of the crosslinked membrane was sulfonated at 80degreesC for 22 h, the PVDF ion exchange membrane can attain 0.8 Omega . cm(2) area resistance in NaCl aqueous solution at 25degreesC, IEC is as high as 2.43 millimoles per grain of the wet membrane. The hydrophilicity of PVDF membrane is also significantly improved after treatment. When 60% of crosslinked membrane was sulfonated at 80degreesC for 6 h, water uptake of the treated membrane can attain 64.7%.
基金Funded by the National Natural Science Foundation of China(51677045)the Natural Science Foundation of Heilongjiang Province of China(E201224)
文摘Two different morphologies of ZnO（lotus-shaped, rod-shaped） and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. Fourier transform infrared spectroscopy（FT-IR）, thermal gravimetry（TG）, and X-ray diffraction（XRD） were also used to characterize the chemical structures and phase composites of ZnO and ZnO/PVDF composite materials. Breakdown voltage, dielectric constant and dielectric loss of ZnO/PVDF composite materials were also tested. Microstructure analysis showed that ZnO nanoparticles dispersed uniformly in the matrix. And the dielectric constant expresses a significantly improvement while the dielectric loss and breakdown voltage expresses no significant change. Moreover, dielectric constant keeps an improvement tendency with increasing content of ZnO.
基金Acknowledgements This project was supported by the National Natural Science Foundation of China （Nos. 51472012, 51672013, 21521001, and 21431006）, and the Fundamental Research Funds for the Central Universities.
文摘Arm symmetrical PbS dendrite （ASD-PbS） nanostructures can be prepared on a large scale by a solvothermal process. The ASD-PbSs exhibit a three-dimensional symmetrical structure, and each dendrite grows multiple branches on the main trunk. Such unique ASD-PbSs can be combined with polyvinylidene fluoride （PVDF） to prepare a composite material with enhanced dielectric and microwave-absorption properties. A detailed investigation of the dependence of the dielectric properties on the frequency and temperature shows that the ASD-PbS/PVDF composite has an ultrahigh dielectric constant and a low percolation threshold. The dielectric permittivity is as high as 1,548 when the concentration of the ASD-PbS filler reaches 13.79 vol.% at 102 Hz, which is 150 times larger than that of pure PVDF, while the composite is as flexible as pure PVDF. Furthermore, the maximum reflection loss can reach -36.69 dB at 16.16 GHz with a filler content of only 2 wt.%, which indicates excellent microwave absorption. The loss mechanism is also elucidated. The present work demonstrates that the addition of metal sulfide microcrystals to polymer matrix composites provides a useful method for improving the dielectric and microwave-absorption properties.
