Novel thin and flexible broadband electromagnetic microwave absorbers are realized with nanocomposites and achieve a wide frequency tunability （from 10 to 17.2 GHz） by actively adjusting the resistance. The proposed...Novel thin and flexible broadband electromagnetic microwave absorbers are realized with nanocomposites and achieve a wide frequency tunability （from 10 to 17.2 GHz） by actively adjusting the resistance. The proposed absorbers are fabricated by scalable screen printing of optimized nanoparticle ink onto the flexible dielectric composite substrates. Based on the shape memory effects of the substrate and piezoresistive effect of the nanocomposite frequency selective surface, a controllable sheet resistance, and thereby tunable wave absorption performance, can be realized in a temperature-activated and dynamically stable manner. The results provide new dimensions for the design of active electromagnetic devices by utilizing previously underestimated intrinsic properties of the artificial materials and the smart behavior of polymer-based nanocomposites.展开更多
Materials with appropriate adhesive properties are suitable for the fabrication of bionic adhesive pads. In this study, a novel polydimethylsiloxane （PDMS） material enhanced with two types of crosslinkers, carbon na...Materials with appropriate adhesive properties are suitable for the fabrication of bionic adhesive pads. In this study, a novel polydimethylsiloxane （PDMS） material enhanced with two types of crosslinkers, carbon nanotubes and graphene sheets, was fabricated. The Contact Angle （CA） and cross-sectional morphology of the new material were investigated and observed using a CA meter and Scanning Electron Microscopy （SEM）, respectively. CA measurements indicate that the surface energy of the novel material is twice that of the common PDMS material. SEM observations show that carbon nanotubes and graphene sheets are well dispersed in the polymer, a feature that improves the mechanical properties of the new material. The adhesive performance of this novel composite was tested on an in-house fabricated friction machine. Results show that at a preload of only 50 mN, the adhesion of the novel PDMS material is up to -3.7 times that of common PDMS. The maximum macroscale shear strength and normal adhesion reach 4 N·cm^-2 and 1 N·cm^-2, respectively. The adhesive capability of the material is maintained even after hundreds of times of repeated use. This novel material exhibits excellent adhesion, sufficiently high elastic modulus and high repeatability at low preloads.展开更多
The aging (biological deterioration) is a major problem of composite insulators now-a-days. The main thing in aging is to predict how, when and with what speed it occurs and under what conditions it can lead to failur...The aging (biological deterioration) is a major problem of composite insulators now-a-days. The main thing in aging is to predict how, when and with what speed it occurs and under what conditions it can lead to failure and what overall average expected life of a composite insulator is. For this a lot of researches have been done. This review summarizes the methods of artificial field testing (aging), natural testing, standards the developed for aging, techniques of analysis, results achieved until now about various parameters from various locations, handling guidelines and a conclusion on what is further needed.展开更多
The dynamic mechanical behavior of a novel polymeric composite damping material has been investigated in this article. The composite consists of chlorinated polyethylene （CPE）, N,N-dicyclohexyl-2-benzothiazolylsufen...The dynamic mechanical behavior of a novel polymeric composite damping material has been investigated in this article. The composite consists of chlorinated polyethylene （CPE）, N,N-dicyclohexyl-2-benzothiazolylsufenamide （DZ）, 4,4＇-thio-bis（3-methyl-6-tert-buthylphenol） （BPSR） and vapor-grown carbon fiber （VGCF）. It is found that either the position or the intensity of damping peak can be controlled by changing the composition of CPE/DZ/BPSR composite. Within a certain composition region, damping peak maximum depends on CPE/DZ ratio, whereas damping peak position is controlled by BPSR content. Moreover, the improvement of storage modulus can be achieved by incorporation of VGCF. These results may imply that a damping material possessing both good damping properties and high strength can be designed and obtained.展开更多
In this report, a novel thermosensitive poly（N-isopropylacrylamide-co-maleic anhydride-β-cyclodextrin）/（TiO2-multi-wal,led carbon nanotubes） （poly（NIPAM-co-MAH-β-CD）/（TiO2-MWCNTs）） composite was synthesize...In this report, a novel thermosensitive poly（N-isopropylacrylamide-co-maleic anhydride-β-cyclodextrin）/（TiO2-multi-wal,led carbon nanotubes） （poly（NIPAM-co-MAH-β-CD）/（TiO2-MWCNTs）） composite was synthesized by UV light photoinitiating method. The results indicated that MAH modifiedβ-CD （MAH-β-CD） could polymerize to NIPAM by UV light irradiation in the presence of TiO2-MWCNTs composite nanoparticles. The characteristic results confirmed that the TiO2-MWCNTs composite nanoparticles were embedded evenly within the thermally responsive copolymer of NIPAM and MAH-β-CD. The effects of irradiation time and TiO2-MWCNTs concentration on the yield of the composites were investigated by keeping NIPAM to MAH-β- CD mass ratio constant. The optimal polymerization reaction conditions were a TiO2-MWCNTs concentration of 10 wt.% under UV light for the illumination of 3 h.展开更多
Phenol and its derivatives are highly toxic pollutants in industrial wastewater for the ecological environments,so there is essential attention to develop effective means of removing these harmful substances from wate...Phenol and its derivatives are highly toxic pollutants in industrial wastewater for the ecological environments,so there is essential attention to develop effective means of removing these harmful substances from water.In this work,the microorganism was immobilized into polymeric composite gel beads prepared by the effective recombination of natural abundant chitosan(CS)and industrial polyvinyl alcohol(PVA)for treating phenolic compounds.The degradation rate of 99.5%can be achieved to treat 100 mg·L^(1)of phenol at 30℃using the fresh resultant immobilized microorganism,where only 21.1%degradation rate was obtained by the free microorganism under the identical conditions.The recycling experiments of repeated 90 times to treat 100 mg·L^(1)of phenol displayed that the degradation rate of phenol was stable to 99%with the appearance of beads unchanged significantly,indicating the immobilized microorganism possessed excellent operating stability.Moreover,while the phenol derivatives of 100 mg·L^(1)were treated catalytically including pmethylphenol,catechol,and oaminophenol for 24 h by the immobilized microorganism,the degradation rates were all above 95%.The immobilized microorganism into PVACS polymeric composite with excellent operating stability and degradation activity would provide a feasible solution for treating phenolic compounds in water in industrial applications.展开更多
Fiber reinforced composite (FRC) requires a process of grinding, mixing and compounding natural fibers from cellulosic waste streams into a polymer matrix that creates a high-strength fiber composite. In this situatio...Fiber reinforced composite (FRC) requires a process of grinding, mixing and compounding natural fibers from cellulosic waste streams into a polymer matrix that creates a high-strength fiber composite. In this situation, the specified waste or base raw materials used are the waste thermoplastics and different types of cellulosic waste including rice husk and saw dust. FRC is a high-performance fiber composite achieved and made possible through a proprietary molecular re-engineering process by interlinking cellulosic fiber molecules with resins in the FRC material matrix, resulting in a product of exceptional structural properties. In this feat of molecular re-engineering, selected physical and structural properties of wood are effectively cloned and obtained in the FRC component, in addition to other essential qualities in order to produce superior performance properties to conventional wood. The dynamic characteristics of composite structures are largely extracted from the reinforcing of fibres. The fiber, held in place by the matrix resin, contributes to tensile strength in a composite, enhancing the performance properties in the final part, such as strength and rigidity, while minimizing weight. The advantages of composite materials always beat down their disadvantages. In this analysis, we tried to find out FRC advance manufacturing, recycling technology and future perspective for mankind and next generation development. This research will bring a new horizon for future science with FRC technology and every aspect of modern science which will bring a stable dimensional stability by recycling process with minimizing waste for environment and next generation science.展开更多
The oil sorption capacity of composite materials made up of different polymeric fabrics (namely acrylic fabric (AF), polypropylene nonwoven (PP), and silk stocking (SS) as composite out-packing materials) and expanded...The oil sorption capacity of composite materials made up of different polymeric fabrics (namely acrylic fabric (AF), polypropylene nonwoven (PP), and silk stocking (SS) as composite out-packing materials) and expanded perlite (EP) was evaluated for oil removal from the water. The effects of sorbent dosage, desorption time, oil amount in the water, and contact time on composite materials sorption were investigated. The results showed that the optimum quantity of EP was between 0.5 g and 1.0 g for 25 cm2 polymeric fabrics bags. Oil removal efficiency for 6 L/m2 of oil amount in the water was 52%-72%, 44%-63%, and 37%-48% for AF, PP, and SS composite materials, respectively. Oil/water selectivity analysis of different composite materials showed that AF composite material had a very high degree of hydrophobicity and oil sorption capacity of approximately 10.17 g/g. Both oil sorption kinetics and equilibrium studies were carried out, and the equilibrium process of composite materials was described well by the Langmuir isotherm, and the oil sorption kinetics of composite materials showed good correlation coefficients for the pseudo-second order kinetic model. Intra-particle diffusion studies showed that oil sorption mechanism was controlled by the three processes, involving in external liquid membrane diffusion, surface sorption, and intra-particle diffusion.展开更多
基金This project was jointly supported by the National Basic Research Program of China （No. 2013CB934203）, the ＂Strategic Priority Research Program＂ of the Chinese Academy of Sciences （No. XDA09030200）, and the National Natural Science Foundation of China （No. 11225210）.
文摘Novel thin and flexible broadband electromagnetic microwave absorbers are realized with nanocomposites and achieve a wide frequency tunability （from 10 to 17.2 GHz） by actively adjusting the resistance. The proposed absorbers are fabricated by scalable screen printing of optimized nanoparticle ink onto the flexible dielectric composite substrates. Based on the shape memory effects of the substrate and piezoresistive effect of the nanocomposite frequency selective surface, a controllable sheet resistance, and thereby tunable wave absorption performance, can be realized in a temperature-activated and dynamically stable manner. The results provide new dimensions for the design of active electromagnetic devices by utilizing previously underestimated intrinsic properties of the artificial materials and the smart behavior of polymer-based nanocomposites.
基金Acknowledgments The authors would like to thank Mr Y. J. Xue for his help with the SEM measurements, Miss H. H. Zhao for her help in fabricating the graphene sheets, and Mr. X. D Sun for his help in measuring the elastic moduli of tile NPWC and NPWOC materials. This work was supported in part by the National Natural Science Foundation of China （Grant Nos. 51175251, 51275237 and 61161120323）, by the Natural Science Foundation of Jiangsu Province （Grant No. BK2011734）, by the Funding for Outstanding Doctoral Dissertation in NUAA （Grant No. BCXJ11-06）, by the Funding of Jiangsu Innovation Program for Graduate Education （Grant No. CXLX11_0178）, and by the Fundamental Research Funds for Central Universities.
文摘Materials with appropriate adhesive properties are suitable for the fabrication of bionic adhesive pads. In this study, a novel polydimethylsiloxane （PDMS） material enhanced with two types of crosslinkers, carbon nanotubes and graphene sheets, was fabricated. The Contact Angle （CA） and cross-sectional morphology of the new material were investigated and observed using a CA meter and Scanning Electron Microscopy （SEM）, respectively. CA measurements indicate that the surface energy of the novel material is twice that of the common PDMS material. SEM observations show that carbon nanotubes and graphene sheets are well dispersed in the polymer, a feature that improves the mechanical properties of the new material. The adhesive performance of this novel composite was tested on an in-house fabricated friction machine. Results show that at a preload of only 50 mN, the adhesion of the novel PDMS material is up to -3.7 times that of common PDMS. The maximum macroscale shear strength and normal adhesion reach 4 N·cm^-2 and 1 N·cm^-2, respectively. The adhesive capability of the material is maintained even after hundreds of times of repeated use. This novel material exhibits excellent adhesion, sufficiently high elastic modulus and high repeatability at low preloads.
文摘The aging (biological deterioration) is a major problem of composite insulators now-a-days. The main thing in aging is to predict how, when and with what speed it occurs and under what conditions it can lead to failure and what overall average expected life of a composite insulator is. For this a lot of researches have been done. This review summarizes the methods of artificial field testing (aging), natural testing, standards the developed for aging, techniques of analysis, results achieved until now about various parameters from various locations, handling guidelines and a conclusion on what is further needed.
基金supported by Zhejiang Provincial Natural Science Foundation of China(R503223)
文摘The dynamic mechanical behavior of a novel polymeric composite damping material has been investigated in this article. The composite consists of chlorinated polyethylene （CPE）, N,N-dicyclohexyl-2-benzothiazolylsufenamide （DZ）, 4,4＇-thio-bis（3-methyl-6-tert-buthylphenol） （BPSR） and vapor-grown carbon fiber （VGCF）. It is found that either the position or the intensity of damping peak can be controlled by changing the composition of CPE/DZ/BPSR composite. Within a certain composition region, damping peak maximum depends on CPE/DZ ratio, whereas damping peak position is controlled by BPSR content. Moreover, the improvement of storage modulus can be achieved by incorporation of VGCF. These results may imply that a damping material possessing both good damping properties and high strength can be designed and obtained.
基金the financial support provided by the National Natural Science Foundation of China (No.20977013)
文摘In this report, a novel thermosensitive poly（N-isopropylacrylamide-co-maleic anhydride-β-cyclodextrin）/（TiO2-multi-wal,led carbon nanotubes） （poly（NIPAM-co-MAH-β-CD）/（TiO2-MWCNTs）） composite was synthesized by UV light photoinitiating method. The results indicated that MAH modifiedβ-CD （MAH-β-CD） could polymerize to NIPAM by UV light irradiation in the presence of TiO2-MWCNTs composite nanoparticles. The characteristic results confirmed that the TiO2-MWCNTs composite nanoparticles were embedded evenly within the thermally responsive copolymer of NIPAM and MAH-β-CD. The effects of irradiation time and TiO2-MWCNTs concentration on the yield of the composites were investigated by keeping NIPAM to MAH-β- CD mass ratio constant. The optimal polymerization reaction conditions were a TiO2-MWCNTs concentration of 10 wt.% under UV light for the illumination of 3 h.
基金the National Natural Science Foundation of China(No.21961028)the Science and Technology Support Project of Ningxia Province(NX015076)。
文摘Phenol and its derivatives are highly toxic pollutants in industrial wastewater for the ecological environments,so there is essential attention to develop effective means of removing these harmful substances from water.In this work,the microorganism was immobilized into polymeric composite gel beads prepared by the effective recombination of natural abundant chitosan(CS)and industrial polyvinyl alcohol(PVA)for treating phenolic compounds.The degradation rate of 99.5%can be achieved to treat 100 mg·L^(1)of phenol at 30℃using the fresh resultant immobilized microorganism,where only 21.1%degradation rate was obtained by the free microorganism under the identical conditions.The recycling experiments of repeated 90 times to treat 100 mg·L^(1)of phenol displayed that the degradation rate of phenol was stable to 99%with the appearance of beads unchanged significantly,indicating the immobilized microorganism possessed excellent operating stability.Moreover,while the phenol derivatives of 100 mg·L^(1)were treated catalytically including pmethylphenol,catechol,and oaminophenol for 24 h by the immobilized microorganism,the degradation rates were all above 95%.The immobilized microorganism into PVACS polymeric composite with excellent operating stability and degradation activity would provide a feasible solution for treating phenolic compounds in water in industrial applications.
文摘Fiber reinforced composite (FRC) requires a process of grinding, mixing and compounding natural fibers from cellulosic waste streams into a polymer matrix that creates a high-strength fiber composite. In this situation, the specified waste or base raw materials used are the waste thermoplastics and different types of cellulosic waste including rice husk and saw dust. FRC is a high-performance fiber composite achieved and made possible through a proprietary molecular re-engineering process by interlinking cellulosic fiber molecules with resins in the FRC material matrix, resulting in a product of exceptional structural properties. In this feat of molecular re-engineering, selected physical and structural properties of wood are effectively cloned and obtained in the FRC component, in addition to other essential qualities in order to produce superior performance properties to conventional wood. The dynamic characteristics of composite structures are largely extracted from the reinforcing of fibres. The fiber, held in place by the matrix resin, contributes to tensile strength in a composite, enhancing the performance properties in the final part, such as strength and rigidity, while minimizing weight. The advantages of composite materials always beat down their disadvantages. In this analysis, we tried to find out FRC advance manufacturing, recycling technology and future perspective for mankind and next generation development. This research will bring a new horizon for future science with FRC technology and every aspect of modern science which will bring a stable dimensional stability by recycling process with minimizing waste for environment and next generation science.
基金National Important Science & Technology Specific Projects of China ( No. 2009ZX07317-006-02,No. 2009ZX07318-008-007)State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology,China ( No. 2013DX06)
文摘The oil sorption capacity of composite materials made up of different polymeric fabrics (namely acrylic fabric (AF), polypropylene nonwoven (PP), and silk stocking (SS) as composite out-packing materials) and expanded perlite (EP) was evaluated for oil removal from the water. The effects of sorbent dosage, desorption time, oil amount in the water, and contact time on composite materials sorption were investigated. The results showed that the optimum quantity of EP was between 0.5 g and 1.0 g for 25 cm2 polymeric fabrics bags. Oil removal efficiency for 6 L/m2 of oil amount in the water was 52%-72%, 44%-63%, and 37%-48% for AF, PP, and SS composite materials, respectively. Oil/water selectivity analysis of different composite materials showed that AF composite material had a very high degree of hydrophobicity and oil sorption capacity of approximately 10.17 g/g. Both oil sorption kinetics and equilibrium studies were carried out, and the equilibrium process of composite materials was described well by the Langmuir isotherm, and the oil sorption kinetics of composite materials showed good correlation coefficients for the pseudo-second order kinetic model. Intra-particle diffusion studies showed that oil sorption mechanism was controlled by the three processes, involving in external liquid membrane diffusion, surface sorption, and intra-particle diffusion.
