In the field of roads,due to the effect of vehicle loads,piezoelectric materials under the road surface can convert mechanical vibration into electrical energy,which can be further used in road facilities such as traf...In the field of roads,due to the effect of vehicle loads,piezoelectric materials under the road surface can convert mechanical vibration into electrical energy,which can be further used in road facilities such as traffic signals and street lamps.The barium titanate/polyvinylidene fluoride(BaTiO_(3)/PVDF)composite,the most common hybrid ceramic-polymer system,was widely used in various fields because the composite combines the good dielectric property of ceramic materials with the good flexibility of PVDF material.Previous studies have found that conductive particles can further improve the dielectric and piezoelectric properties of other composites.However,few studies have investigated the effect of conductive carbon black on the dielectric and piezoelectric properties of BaTiO_(3)/PVDF composites.In this study,BaTiO_(3)/PVDF/conductive carbon black composites were prepared with various conductive carbon black contents based on the optimum ratio of BaTiO_(3)to PVDF.The effects of conductive carbon black content on the morphologies,thermal performance,conductivities,dielectric properties,and piezoelectric properties of the BaTiO_(3)/PVDF/conductive carbon black composites were then investigated.The addition of conductive carbon black greatly enhances the conductivities,dielectric properties,and piezoelectric properties of the BaTiO_(3)/PVDF/conductive carbon black composites,especially when the carbon black content is 0.8%by weight of PVDF.Additionally,the conductive carbon black does not have an obvious effect on the morphologies and thermal stabilities of BaTiO_(3)/PVDF/conductive carbon black composites.展开更多
The oxides Eu, Ho, Er and Dy were used to prepare the hydroxides of rare earth modified carbon black. Then natural rubber latex （NRL） was added into the reactor. The system reacted at 85 ℃ with stirring for 1 h to ...The oxides Eu, Ho, Er and Dy were used to prepare the hydroxides of rare earth modified carbon black. Then natural rubber latex （NRL） was added into the reactor. The system reacted at 85 ℃ with stirring for 1 h to prepare powdered HAF-Ln（OH）3/NR composites. The effects of the kind and content of Ln on the particle size distribution of P [ NR/HAF-Ln （OH）3 ] and mechanical properties of its vulcanizate were studied respectively. It is found that rare earth can help to get the powder of the composite, the product particle with a diameter less than 0.9mm will be get when the composites containing the compound of Ho, Er and Dy with dosage of 1.0, 1.0, O. 5 percent, respectively. The adding of Ln can improve the tensile strength and tear strength of the vulcanizate effectively, what＇s more, Er and Dy can decrease the permanent set of vulcanizate significantly. The SEM studies shows that P[ NR/HAF-Dy （OH）3 ] vulcanizate shows superior mechanical properties that depend primarily on the absence of free carbon black, the fine dispersion of carbon black in the rubber matrix and better polymer-filler interaction.展开更多
The mechanical, electrical, and thermal expansion properties of carbon nanotube（CNT）-based silver and silver–palladium（10：1, w/w） alloy nanocomposites are reported. To tailor the properties of silver, CNTs were ...The mechanical, electrical, and thermal expansion properties of carbon nanotube（CNT）-based silver and silver–palladium（10：1, w/w） alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified molecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, embedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver–palladium nanocomposite with CNT resulted in increases in the hardness and Young＇s modulus along with concomitant decreases in the electrical conductivity and the coefficient of thermal expansion（CTE）. The hardness and Young＇s modulus of the nanocomposites were increased by 30%？40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical properties of the CNT-reinforced silver and silver–palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying element.展开更多
This work uses the molecular dynamics approach to study the effects of functionalization of carbon nanotubes(CNTs)on the mechanical properties of Cu64Zr36 metallic glass(MG).Three types of functional groups,carboxylic...This work uses the molecular dynamics approach to study the effects of functionalization of carbon nanotubes(CNTs)on the mechanical properties of Cu64Zr36 metallic glass(MG).Three types of functional groups,carboxylic,vinyl and ester were used.The effect of CNT volume fraction(Vf)and the number of functional groups attached to CNT,on the mechanical properties and thermal conductivity of CNT-MG composites was analysed using Biovia Materials Studio.At lower values of Vf(from 0 to 5%),the percentage increase in Young’s modulus was approximately 66%.As the value of Vf was increased further(from 5 to 12%),the rate of increase in Young’s modulus was reduced to 16%.The thermal conductivity was found to increase from 1.52 W/mK at Vf?0%to 5.88 W/mK at Vf?12%,thus giving an increase of approximately 286%.Functionalization of SWCNT reduced the thermal conductivity of the SWCNT-MG composites.展开更多
The present work aims to present the results based on the processing of nanocomposites,which consist of matrix materials like epoxy and filler materials such as conjugated nanomaterials/allotropes of carbon,namely,car...The present work aims to present the results based on the processing of nanocomposites,which consist of matrix materials like epoxy and filler materials such as conjugated nanomaterials/allotropes of carbon,namely,carbon black,graphite,and multiwalled carbon nanotube(MWCNT)used for targeted applications.To improve the physical and chemical properties and to facilitate a better interfacial interface between the polymer and nanotube,functional MWCNT is used during the preparation of the composite.The prime objective of the study is to establish the thermal,mechanical,and electrical properties of nanocomposites using experimental methods.It has been observed from the experimental results that carbon nanotube(CNT)based composite exhibits higher mechanical(tensile and hardness)and thermal properties as compared with the others.The electrical properties are found to be better in a graphite-based composite.Although CNT has superior mechanical and thermal properties,the exorbitant price limits its use.Hence,the allotropes of carbon may be used judiciously considering both the cost and property requirements of the targeted application.The work also studies the dispersion state of nanofibers through scanning electron microscopy(SEM).展开更多
热界面材料是解决现代高功率和高集成化电子器件热量聚集和耗散的有效手段。基于三维网络结构调控导热性能的策略,以三聚氰胺泡沫(MF)为骨架,采用化学表面改性制备碳纳米管三维网络结构(CNT),并采用真空浸润法制备碳纳米管/天然橡胶热...热界面材料是解决现代高功率和高集成化电子器件热量聚集和耗散的有效手段。基于三维网络结构调控导热性能的策略,以三聚氰胺泡沫(MF)为骨架,采用化学表面改性制备碳纳米管三维网络结构(CNT),并采用真空浸润法制备碳纳米管/天然橡胶热界面复合材料(CNT/NR),研究CNT含量对材料微观结构、导热性能和热管理性能的影响。结果表明,当CNT的含量为2.2%(质量分数)时,CNT可附着于MF骨架并呈现完整连续的三维网络结构,其热界面复合材料垂直面外的导热率为1.58 W m^(-1) K^(-1),拉伸强度为12.9 MPa,断裂伸长率为489%,并具有显著的热管理性能,这表明CNT/NR热界面复合材料有望成为一种机具应用价值的热管理材料。展开更多
基金We are grateful for the financial supported by the National Natural Science Foundation of China(Grant No.52178408)the National Key R&D Program of China(Grant No.2018YFE0103800).
文摘In the field of roads,due to the effect of vehicle loads,piezoelectric materials under the road surface can convert mechanical vibration into electrical energy,which can be further used in road facilities such as traffic signals and street lamps.The barium titanate/polyvinylidene fluoride(BaTiO_(3)/PVDF)composite,the most common hybrid ceramic-polymer system,was widely used in various fields because the composite combines the good dielectric property of ceramic materials with the good flexibility of PVDF material.Previous studies have found that conductive particles can further improve the dielectric and piezoelectric properties of other composites.However,few studies have investigated the effect of conductive carbon black on the dielectric and piezoelectric properties of BaTiO_(3)/PVDF composites.In this study,BaTiO_(3)/PVDF/conductive carbon black composites were prepared with various conductive carbon black contents based on the optimum ratio of BaTiO_(3)to PVDF.The effects of conductive carbon black content on the morphologies,thermal performance,conductivities,dielectric properties,and piezoelectric properties of the BaTiO_(3)/PVDF/conductive carbon black composites were then investigated.The addition of conductive carbon black greatly enhances the conductivities,dielectric properties,and piezoelectric properties of the BaTiO_(3)/PVDF/conductive carbon black composites,especially when the carbon black content is 0.8%by weight of PVDF.Additionally,the conductive carbon black does not have an obvious effect on the morphologies and thermal stabilities of BaTiO_(3)/PVDF/conductive carbon black composites.
文摘The oxides Eu, Ho, Er and Dy were used to prepare the hydroxides of rare earth modified carbon black. Then natural rubber latex （NRL） was added into the reactor. The system reacted at 85 ℃ with stirring for 1 h to prepare powdered HAF-Ln（OH）3/NR composites. The effects of the kind and content of Ln on the particle size distribution of P [ NR/HAF-Ln （OH）3 ] and mechanical properties of its vulcanizate were studied respectively. It is found that rare earth can help to get the powder of the composite, the product particle with a diameter less than 0.9mm will be get when the composites containing the compound of Ho, Er and Dy with dosage of 1.0, 1.0, O. 5 percent, respectively. The adding of Ln can improve the tensile strength and tear strength of the vulcanizate effectively, what＇s more, Er and Dy can decrease the permanent set of vulcanizate significantly. The SEM studies shows that P[ NR/HAF-Dy （OH）3 ] vulcanizate shows superior mechanical properties that depend primarily on the absence of free carbon black, the fine dispersion of carbon black in the rubber matrix and better polymer-filler interaction.
基金the financial assistance received from the Department of Science and Technology(Government of India)for conducting this investigation(Project-SR/FTP/PS-054/2011(G))
文摘The mechanical, electrical, and thermal expansion properties of carbon nanotube（CNT）-based silver and silver–palladium（10：1, w/w） alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified molecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, embedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver–palladium nanocomposite with CNT resulted in increases in the hardness and Young＇s modulus along with concomitant decreases in the electrical conductivity and the coefficient of thermal expansion（CTE）. The hardness and Young＇s modulus of the nanocomposites were increased by 30%？40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical properties of the CNT-reinforced silver and silver–palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying element.
文摘This work uses the molecular dynamics approach to study the effects of functionalization of carbon nanotubes(CNTs)on the mechanical properties of Cu64Zr36 metallic glass(MG).Three types of functional groups,carboxylic,vinyl and ester were used.The effect of CNT volume fraction(Vf)and the number of functional groups attached to CNT,on the mechanical properties and thermal conductivity of CNT-MG composites was analysed using Biovia Materials Studio.At lower values of Vf(from 0 to 5%),the percentage increase in Young’s modulus was approximately 66%.As the value of Vf was increased further(from 5 to 12%),the rate of increase in Young’s modulus was reduced to 16%.The thermal conductivity was found to increase from 1.52 W/mK at Vf?0%to 5.88 W/mK at Vf?12%,thus giving an increase of approximately 286%.Functionalization of SWCNT reduced the thermal conductivity of the SWCNT-MG composites.
文摘The present work aims to present the results based on the processing of nanocomposites,which consist of matrix materials like epoxy and filler materials such as conjugated nanomaterials/allotropes of carbon,namely,carbon black,graphite,and multiwalled carbon nanotube(MWCNT)used for targeted applications.To improve the physical and chemical properties and to facilitate a better interfacial interface between the polymer and nanotube,functional MWCNT is used during the preparation of the composite.The prime objective of the study is to establish the thermal,mechanical,and electrical properties of nanocomposites using experimental methods.It has been observed from the experimental results that carbon nanotube(CNT)based composite exhibits higher mechanical(tensile and hardness)and thermal properties as compared with the others.The electrical properties are found to be better in a graphite-based composite.Although CNT has superior mechanical and thermal properties,the exorbitant price limits its use.Hence,the allotropes of carbon may be used judiciously considering both the cost and property requirements of the targeted application.The work also studies the dispersion state of nanofibers through scanning electron microscopy(SEM).
文摘热界面材料是解决现代高功率和高集成化电子器件热量聚集和耗散的有效手段。基于三维网络结构调控导热性能的策略,以三聚氰胺泡沫(MF)为骨架,采用化学表面改性制备碳纳米管三维网络结构(CNT),并采用真空浸润法制备碳纳米管/天然橡胶热界面复合材料(CNT/NR),研究CNT含量对材料微观结构、导热性能和热管理性能的影响。结果表明,当CNT的含量为2.2%(质量分数)时,CNT可附着于MF骨架并呈现完整连续的三维网络结构,其热界面复合材料垂直面外的导热率为1.58 W m^(-1) K^(-1),拉伸强度为12.9 MPa,断裂伸长率为489%,并具有显著的热管理性能,这表明CNT/NR热界面复合材料有望成为一种机具应用价值的热管理材料。
