The growing concern about thermal conductivityand electromagnetic shielding inelectronic equipment has promoted the development of interfacial film materials.In this work,polyvinylidene fluoride(PVDF)/graphene composi...The growing concern about thermal conductivityand electromagnetic shielding inelectronic equipment has promoted the development of interfacial film materials.In this work,polyvinylidene fluoride(PVDF)/graphene composite films with different graphene contents were fabricated by high-energy ball milling,cold isostatic pressing,scraping and coating,successively.High-energy ball milling is beneficial to the dispersion of graphene powder,while cold isostatic pressing can greatly enhance thermal conductivity and mechanical strength by reducing the voids in the film and increasing the contact area of graphene sheets.The thermal conductivity,tensile strength and electromagnetic shielding properties of the films were carefully investigated and compared.It was demonstrated that the thermal conductivity increased from 0.19 Wm-1.K-1 for pure PVDF to 103.9 W-m-1.K-1 for the composite film with PVDF:graphene=1:3.Meanwhile the electromagnetic shielding efficiency can reach 36.55 dB.The prepared PVDF/graphene composite films exhibit outstanding overall performance and have the potential for practical applications.展开更多
The mechanical properties and material volume fractions of PTFE/Kevlar49/PA6 composite are studied. The focus of this paper is to get the relationship between the volume fraction of three constituents and the mechanic...The mechanical properties and material volume fractions of PTFE/Kevlar49/PA6 composite are studied. The focus of this paper is to get the relationship between the volume fraction of three constituents and the mechanical properties of the composite by doing tensile, hardness and wear test. The effect of the constituent volume fractions was evaluated. Short Kevlar49 fibers reinforced PA6 （Polyamide 6） with PTFE filler were studied in five different combinations. The results of the experiments show that the mechanical properties increase with Keviar fibers increase, then they decrease after the Kevlar fiber volume reaches one number.展开更多
Objective： To fabricate polymeric nanocomposites with excellent photoluminescence, magnetic properties, and stability in aqueous solutions, in order to improve specificity and sensitivity of cellular imaging under a ...Objective： To fabricate polymeric nanocomposites with excellent photoluminescence, magnetic properties, and stability in aqueous solutions, in order to improve specificity and sensitivity of cellular imaging under a magnetic field. Methods： Fluoridated LnS＋-doped HAP （Ln3＋-HAP） NPs and iron oxides （lOs） can be encapsulated with biocompatible polymers via a modified solvent exaction/evaporation technique to prepare polymeric nanocomposites with fluoridated Ln3＋-HAP/iron oxide. The nanocomposites were characterized for surface morphology, fluorescence spectra, magnetic properties and in vitro cytotoxicity. Magnetic targeted cellular imaging of such nanocomposites was also evaluated with confocal laser scanning microscope using A549 cells with or without magnetic field. Results： The fabricated nanocomposites showed good stability and excellent luminescent properties, as well as low in vitro cytotoxicity, indicating that the nanocomposites are suitable for biological applications. Nanocomposites under magnetic field achieved much higher cellular uptake via an energy-dependent pathway than those without magnetic field. Conclusion： 1tie nanocomposites fabricated in this study will be a promising tool for magnetic targeted cellular imaging with improved specificity and enhanced selection.展开更多
Relaxor ferroelectric polymers display great potential in capacitor dielectric applications because of their excellent flexibility,light weight,and high dielectric constant.However,their electrical energy storage capa...Relaxor ferroelectric polymers display great potential in capacitor dielectric applications because of their excellent flexibility,light weight,and high dielectric constant.However,their electrical energy storage capacity is limited by their high conduction losses and low dielectric strength,which primarily originates from the impact-ionization-induced electron multiplication,low mechanical modulus,and low thermal conductivity of the dielectric polymers.Here a matrix free strategy is developed to effectively suppress electron multiplication effects and to enhance mechanical modulus and thermal conductivity of a dielectric polymer,which involves the chemical adsorption of an electron barrier layer on boron nitride nanosheet surfaces by chemically adsorbing an amino-containing polymer.A dramatic decrease of leakage current(from 2.4×10^(-6)to 1.1×10^(-7)A cm^(-2)at 100 MV m^(-1))and a substantial increase of breakdown strength(from 340 to 742 MV m^(-1))were achieved in the nanocompostes,which result in a remarkable increase of discharge energy density(from 5.2 to 31.8 J cm^(-3)).Moreover,the dielectric strength of the nanocomposites suffering an electrical breakdown could be restored to 88%of the original value.This study demonstrates a rational design for fabricating dielectric polymer nanocomposites with greatly enhanced electric energy storage capacity.展开更多
The aim of this project was to develop non-contact fiber optic based displacement sensors to operate in the harsh environment of a ＂light gas gun＂ （LGG）, which can ＂fire＂ small particles at velocities ranging fr...The aim of this project was to develop non-contact fiber optic based displacement sensors to operate in the harsh environment of a ＂light gas gun＂ （LGG）, which can ＂fire＂ small particles at velocities ranging from 1 km/s-8.4km/s. The LGG is used extensively for research in aerospace to analyze the effects of high speed impacts on materials. Ideally the measurement should be made close to the center of the impact to minimize corruption of the data from edge effects and survive the impact. We chose to develop a non-contact ＂pseudo＂ confocal intensity sensor, which demonstrated resolution comparable with conventional polyvinylidene fluoride （PVDF） sensors combined with high survivability and low cost. A second sensor was developed based on ＂fiber Bragg gratings＂ （FBG） to enable a more detailed analysis of the effects of the impact, although requiring contact with the target the low weight and very small contact area of the FBG had minimal effect on the dynamics of the target. The FBG was mounted either on the surface of the target or tangentially between a fixed location. The output signals from the FBG were interrogated in time by a new method. Measurements were made on carbon fiber composite plates in the LGG and on low velocity impact tests. The particle momentum for the low velocity impact tests was chosen to be similar to that of the particles used in the LGG.展开更多
基金This work was supported by the National Natural ScienceFoundationofChina(No.U22B2066,No.12064044)the Major Science and Technology Projects of Anhui Province(No.202103a05020016)+1 种基金the open competition project to select the best candidates to undertake major science and key research projectsofTonglingcity,AnhuiProvince(No.202101JB002)A proportion of this work was supported by the High Magnetic Field Laboratory of Anhui Province and Academician workstation of Hangzhou Xingyu Carbon Environmental Tech Co.,Ltd.,and the Hefei Institutes of Physical Science Director's Fund(No.YZJJ-GGZX-2022-01).
文摘The growing concern about thermal conductivityand electromagnetic shielding inelectronic equipment has promoted the development of interfacial film materials.In this work,polyvinylidene fluoride(PVDF)/graphene composite films with different graphene contents were fabricated by high-energy ball milling,cold isostatic pressing,scraping and coating,successively.High-energy ball milling is beneficial to the dispersion of graphene powder,while cold isostatic pressing can greatly enhance thermal conductivity and mechanical strength by reducing the voids in the film and increasing the contact area of graphene sheets.The thermal conductivity,tensile strength and electromagnetic shielding properties of the films were carefully investigated and compared.It was demonstrated that the thermal conductivity increased from 0.19 Wm-1.K-1 for pure PVDF to 103.9 W-m-1.K-1 for the composite film with PVDF:graphene=1:3.Meanwhile the electromagnetic shielding efficiency can reach 36.55 dB.The prepared PVDF/graphene composite films exhibit outstanding overall performance and have the potential for practical applications.
文摘The mechanical properties and material volume fractions of PTFE/Kevlar49/PA6 composite are studied. The focus of this paper is to get the relationship between the volume fraction of three constituents and the mechanical properties of the composite by doing tensile, hardness and wear test. The effect of the constituent volume fractions was evaluated. Short Kevlar49 fibers reinforced PA6 （Polyamide 6） with PTFE filler were studied in five different combinations. The results of the experiments show that the mechanical properties increase with Keviar fibers increase, then they decrease after the Kevlar fiber volume reaches one number.
基金supported by National Natural Science Foundation of China (Grant No. 21506161, 31270019)National Key Basic Research Program of China (973 Program) (Grant No. 2011CB933100, 2011CB932402)+1 种基金Guangdong Natural Science Funds for Distinguished Young Scholar (Grant No. 2014A030306036)open funds from the Key Laboratory of Biomedical Materials in Tianjin
文摘Objective： To fabricate polymeric nanocomposites with excellent photoluminescence, magnetic properties, and stability in aqueous solutions, in order to improve specificity and sensitivity of cellular imaging under a magnetic field. Methods： Fluoridated LnS＋-doped HAP （Ln3＋-HAP） NPs and iron oxides （lOs） can be encapsulated with biocompatible polymers via a modified solvent exaction/evaporation technique to prepare polymeric nanocomposites with fluoridated Ln3＋-HAP/iron oxide. The nanocomposites were characterized for surface morphology, fluorescence spectra, magnetic properties and in vitro cytotoxicity. Magnetic targeted cellular imaging of such nanocomposites was also evaluated with confocal laser scanning microscope using A549 cells with or without magnetic field. Results： The fabricated nanocomposites showed good stability and excellent luminescent properties, as well as low in vitro cytotoxicity, indicating that the nanocomposites are suitable for biological applications. Nanocomposites under magnetic field achieved much higher cellular uptake via an energy-dependent pathway than those without magnetic field. Conclusion： 1tie nanocomposites fabricated in this study will be a promising tool for magnetic targeted cellular imaging with improved specificity and enhanced selection.
基金supported by the National Natural Science Foundation of China(52003153,51877132 and 52002300)Program of Shanghai Academic Research Leader(21XD1401600)+1 种基金State Key Laboratory of Electrical Insulation and Power Equipment(EIPE20203,EIPE21206)the Major Research Plan of National Natural Science Foundation of China(92066103)。
文摘Relaxor ferroelectric polymers display great potential in capacitor dielectric applications because of their excellent flexibility,light weight,and high dielectric constant.However,their electrical energy storage capacity is limited by their high conduction losses and low dielectric strength,which primarily originates from the impact-ionization-induced electron multiplication,low mechanical modulus,and low thermal conductivity of the dielectric polymers.Here a matrix free strategy is developed to effectively suppress electron multiplication effects and to enhance mechanical modulus and thermal conductivity of a dielectric polymer,which involves the chemical adsorption of an electron barrier layer on boron nitride nanosheet surfaces by chemically adsorbing an amino-containing polymer.A dramatic decrease of leakage current(from 2.4×10^(-6)to 1.1×10^(-7)A cm^(-2)at 100 MV m^(-1))and a substantial increase of breakdown strength(from 340 to 742 MV m^(-1))were achieved in the nanocompostes,which result in a remarkable increase of discharge energy density(from 5.2 to 31.8 J cm^(-3)).Moreover,the dielectric strength of the nanocomposites suffering an electrical breakdown could be restored to 88%of the original value.This study demonstrates a rational design for fabricating dielectric polymer nanocomposites with greatly enhanced electric energy storage capacity.
文摘The aim of this project was to develop non-contact fiber optic based displacement sensors to operate in the harsh environment of a ＂light gas gun＂ （LGG）, which can ＂fire＂ small particles at velocities ranging from 1 km/s-8.4km/s. The LGG is used extensively for research in aerospace to analyze the effects of high speed impacts on materials. Ideally the measurement should be made close to the center of the impact to minimize corruption of the data from edge effects and survive the impact. We chose to develop a non-contact ＂pseudo＂ confocal intensity sensor, which demonstrated resolution comparable with conventional polyvinylidene fluoride （PVDF） sensors combined with high survivability and low cost. A second sensor was developed based on ＂fiber Bragg gratings＂ （FBG） to enable a more detailed analysis of the effects of the impact, although requiring contact with the target the low weight and very small contact area of the FBG had minimal effect on the dynamics of the target. The FBG was mounted either on the surface of the target or tangentially between a fixed location. The output signals from the FBG were interrogated in time by a new method. Measurements were made on carbon fiber composite plates in the LGG and on low velocity impact tests. The particle momentum for the low velocity impact tests was chosen to be similar to that of the particles used in the LGG.
