Wearable strain sensors based on flexible conductive polymer composites(FCPCs)have attracted great attention due to their applications in the fields of human–machine interaction,disease diagnostics,human motion detec...Wearable strain sensors based on flexible conductive polymer composites(FCPCs)have attracted great attention due to their applications in the fields of human–machine interaction,disease diagnostics,human motion detection,and soft robotic skin.In recent decades,FCPC‐based strain sensors with high stretchability and sensitivity,short response time,and excellent stability have been developed,which are expected to be more versatile and intelligent.Smart strain sensors are required to provide wearable comfort,such as breathability,selfcooling ability,and so forth.To adapt to the harsh environment,wearable strain sensors should also be highly adaptive to protect the skin and the sensor itself.In addition,portable power supply system,multisite sensing capability,and multifunctionality are crucial for the next generation of FCPC‐based strain sensor.展开更多
Electromagnetic interference(EMI)shielding materials are in great demand in electronic equipment and our surrounding environment to resist the increasing serious radiation pollution.Compared with their metal counterpa...Electromagnetic interference(EMI)shielding materials are in great demand in electronic equipment and our surrounding environment to resist the increasing serious radiation pollution.Compared with their metal counterparts,conductive polymer composites(CPCs)have unique advantages of lightweight,corrosive resistance,low cost,and excellent processability,and are therefore an ideal choice for developing high-performance EMI shielding materials.However,CPCs based EMI shielding materials are limited to high filler loading,which caused poor mechanical properties and processability.Here,we demonstrate a facile and highly scalable approach to develop high-performance EMI shielding materials with low filler loading by using miscible poly(phenylene oxide)/polystyrene(PPO/PS)blend as the matrix.In contrast to PS/carbon nanotubes(CNTs)composites,PPO/PS/CNTs composites show much higher EMI shielding effectiveness caused by good dispersion of CNTs and highly interconnected conductive network.An excellent EMI shieling effectiveness of 23-25 dB is achieved for PPO/PS/10%CNTs composites with a thickness of only 375 pm;which is superior to most of reported polymer/CNTs composites prepared by melt-compounding.In addition,the results show that although absorption is the major shielding mechanism,the contribution of reflection is also important and closely related to the connectivity of conductive network,as well as the electrical conductivity of the CPCs.展开更多
Theoretical and empirical models for predicting the thermal conductivity of polymer composites were summarized since the 1920s.The effects of particle shape,filler amount,dispersion state of fillers,and interfacial th...Theoretical and empirical models for predicting the thermal conductivity of polymer composites were summarized since the 1920s.The effects of particle shape,filler amount,dispersion state of fillers,and interfacial thermal barrier on the thermal conductivity of filled polymer composites were investigated,and the agreement of experimental data with theoretical models in literatures was discussed.Silica with high thermal conductivity was chosen to mix with polyvinyl-acetate （EVA） copolymer to prepare SiO2/EVA co-films.Experimental data of the co-films＇ thermal conductivity were compared with some classical theoretical and empirical models.The results show that Agari＇s model,the mixed model,and the percolation model can predict well the thermal conductivity of SiO2/EVA co-films.展开更多
Fiber-polymer composites exhibit extraordianary and unusual properties. Depending on the fiber type and arrangementt the following can be achieved: a very high tensile strength and stiffness or fatigue strength, a zer...Fiber-polymer composites exhibit extraordianary and unusual properties. Depending on the fiber type and arrangementt the following can be achieved: a very high tensile strength and stiffness or fatigue strength, a zero or negative thermal expension, a rather high damping capability and a very high thermal and electrical insulating performance. But even carbon fibers can be converted into excellent electrical conductors when calined with fluorine. However, the shear properties of fiber composites with a polymeric matrix are medium. Extreme mechanical and thermal cryogenic properties will be discussed and compared to those of other material classes. Special emphasis is put on present and future cryogenic applications including storage and transportation of hydrogen or liquefied gases. Gas permeation through composites afier mechani-cal and thermal cycling and modifications for a better performance will be discassed.Further trends for getting advanced materials will finish the presentation.展开更多
The multi-walled carbon nanotubes (MWCNTs)/chiral-polyaniline composite was synthesized by in-situ chemical polymerization. Morphology, structure as well as thermal stability of the hybrid composites were characterize...The multi-walled carbon nanotubes (MWCNTs)/chiral-polyaniline composite was synthesized by in-situ chemical polymerization. Morphology, structure as well as thermal stability of the hybrid composites were characterized by using various techniques. Moreover, the complex permeability, permittivity, and microwave absorbing characteristics of the MWCNTs/chiral-polyaniline composites have been studied. Compared with those of the polyaniline (PANI) and MWCNTs, the real part () and imaginary part () of the complex permittivity as well as dielectric dissipation factor of the MWCNTs/chiral-PANI composites were much greater, while the real part () and imaginary part () of the complex permeability and the magnetic dissipation factor were smaller. The results indicate that the microwave absorption of MWCNTs/chiral-PANI composites was mainly attributed to the dielectric loss rather than magnetic loss.展开更多
Current-voltage electrical behavior of in situ microfibrillar carbon black （CB）/poly（ethylene terephthalate） （PET）/polyethylene （PE） （m-CB/PET/PE） composites with various CB concentrations at ambient tempera...Current-voltage electrical behavior of in situ microfibrillar carbon black （CB）/poly（ethylene terephthalate） （PET）/polyethylene （PE） （m-CB/PET/PE） composites with various CB concentrations at ambient temperatures was studied under a direct-current electric field. The current-voltage （l-V） curves exhibited nonlinearity beyond a critical value of voltage. The dynamic random resistor network （DRRN） model was adopted to semi-qualitatively explain the nonlinear conduction behavior of m-CB/PET/PE composites. Macroscopic nonlinearity originated from the interfacial interactions between CB/PET micro fibrils and additional conduction channels. Combined with the special conductive networks, an illustration was proposed to interpret the nonlinear 1-V characteristics by a field emission or tunneling mechanism between CB particles in the CB/PET micro fibers intersections.展开更多
基金Henan Province University Innovation Talents Support Program,Grant/Award Number:20HASTIT001National Natural Science Foundation of China,Grant/Award Numbers:51773183,U1604253,U1804133Innovation Team of Colleges and Universities in Henan Province,Grant/Award Number:20IRTSTHN002。
文摘Wearable strain sensors based on flexible conductive polymer composites(FCPCs)have attracted great attention due to their applications in the fields of human–machine interaction,disease diagnostics,human motion detection,and soft robotic skin.In recent decades,FCPC‐based strain sensors with high stretchability and sensitivity,short response time,and excellent stability have been developed,which are expected to be more versatile and intelligent.Smart strain sensors are required to provide wearable comfort,such as breathability,selfcooling ability,and so forth.To adapt to the harsh environment,wearable strain sensors should also be highly adaptive to protect the skin and the sensor itself.In addition,portable power supply system,multisite sensing capability,and multifunctionality are crucial for the next generation of FCPC‐based strain sensor.
文摘Electromagnetic interference(EMI)shielding materials are in great demand in electronic equipment and our surrounding environment to resist the increasing serious radiation pollution.Compared with their metal counterparts,conductive polymer composites(CPCs)have unique advantages of lightweight,corrosive resistance,low cost,and excellent processability,and are therefore an ideal choice for developing high-performance EMI shielding materials.However,CPCs based EMI shielding materials are limited to high filler loading,which caused poor mechanical properties and processability.Here,we demonstrate a facile and highly scalable approach to develop high-performance EMI shielding materials with low filler loading by using miscible poly(phenylene oxide)/polystyrene(PPO/PS)blend as the matrix.In contrast to PS/carbon nanotubes(CNTs)composites,PPO/PS/CNTs composites show much higher EMI shielding effectiveness caused by good dispersion of CNTs and highly interconnected conductive network.An excellent EMI shieling effectiveness of 23-25 dB is achieved for PPO/PS/10%CNTs composites with a thickness of only 375 pm;which is superior to most of reported polymer/CNTs composites prepared by melt-compounding.In addition,the results show that although absorption is the major shielding mechanism,the contribution of reflection is also important and closely related to the connectivity of conductive network,as well as the electrical conductivity of the CPCs.
基金supported by the High-Tech Research and Development Program of China (863 Program) (No.2006AA050203)
文摘Theoretical and empirical models for predicting the thermal conductivity of polymer composites were summarized since the 1920s.The effects of particle shape,filler amount,dispersion state of fillers,and interfacial thermal barrier on the thermal conductivity of filled polymer composites were investigated,and the agreement of experimental data with theoretical models in literatures was discussed.Silica with high thermal conductivity was chosen to mix with polyvinyl-acetate （EVA） copolymer to prepare SiO2/EVA co-films.Experimental data of the co-films＇ thermal conductivity were compared with some classical theoretical and empirical models.The results show that Agari＇s model,the mixed model,and the percolation model can predict well the thermal conductivity of SiO2/EVA co-films.
文摘Fiber-polymer composites exhibit extraordianary and unusual properties. Depending on the fiber type and arrangementt the following can be achieved: a very high tensile strength and stiffness or fatigue strength, a zero or negative thermal expension, a rather high damping capability and a very high thermal and electrical insulating performance. But even carbon fibers can be converted into excellent electrical conductors when calined with fluorine. However, the shear properties of fiber composites with a polymeric matrix are medium. Extreme mechanical and thermal cryogenic properties will be discussed and compared to those of other material classes. Special emphasis is put on present and future cryogenic applications including storage and transportation of hydrogen or liquefied gases. Gas permeation through composites afier mechani-cal and thermal cycling and modifications for a better performance will be discassed.Further trends for getting advanced materials will finish the presentation.
文摘The multi-walled carbon nanotubes (MWCNTs)/chiral-polyaniline composite was synthesized by in-situ chemical polymerization. Morphology, structure as well as thermal stability of the hybrid composites were characterized by using various techniques. Moreover, the complex permeability, permittivity, and microwave absorbing characteristics of the MWCNTs/chiral-polyaniline composites have been studied. Compared with those of the polyaniline (PANI) and MWCNTs, the real part () and imaginary part () of the complex permittivity as well as dielectric dissipation factor of the MWCNTs/chiral-PANI composites were much greater, while the real part () and imaginary part () of the complex permeability and the magnetic dissipation factor were smaller. The results indicate that the microwave absorption of MWCNTs/chiral-PANI composites was mainly attributed to the dielectric loss rather than magnetic loss.
基金financially supported by the National Science Fund for Distinguished Young Scholars (No. 50925311)National Science Fund of China (Nos. 20976112, 51033004)
文摘Current-voltage electrical behavior of in situ microfibrillar carbon black （CB）/poly（ethylene terephthalate） （PET）/polyethylene （PE） （m-CB/PET/PE） composites with various CB concentrations at ambient temperatures was studied under a direct-current electric field. The current-voltage （l-V） curves exhibited nonlinearity beyond a critical value of voltage. The dynamic random resistor network （DRRN） model was adopted to semi-qualitatively explain the nonlinear conduction behavior of m-CB/PET/PE composites. Macroscopic nonlinearity originated from the interfacial interactions between CB/PET micro fibrils and additional conduction channels. Combined with the special conductive networks, an illustration was proposed to interpret the nonlinear 1-V characteristics by a field emission or tunneling mechanism between CB particles in the CB/PET micro fibers intersections.
