Durable electromagnetic interference(EMI)shielding is highly desired,as electromagnetic pollution is a great concern for electronics’stable performance and human health.Although a superhydrophobic surface can extend ...Durable electromagnetic interference(EMI)shielding is highly desired,as electromagnetic pollution is a great concern for electronics’stable performance and human health.Although a superhydrophobic surface can extend the service lifespan of EMI shielding materials,degradation of its protection capability and insufficient self-healing are troublesome issues due to unavoidable physical/chemical damages under long-term application conditions.Here,we report,for the first time,an instantaneously self-healing approach via microwave heating to achieve durable shielding performance.First,a hydrophobic 1H,1H,2H,2H-perfluorooctyltriethoxysilane(POTS)layer was coated on a polypyrrole(PPy)-modified fabric(PPy@POTS),enabling protection against the invasion of water,salt solution,and corrosive acidic and basic solutions.Moreover,after being damaged,the POTS layer can,for the first time,be instantaneously self-healed via microwave heating for a very short time,i.e.,4 s,benefiting from the intense thermal energy generated by PPy under electromagnetic wave radiation.This self-healing ability is also repeatable even after intentionally severe plasma etching,which highlights the great potential to achieve robust and durable EMI shielding applications.Significantly,this approach can be extended to other EMI shielding materials where heat is a triggering stimulus for healing thin protection layers.We envision that this work could provide insights into fabricating EMI shielding materials with durable performance for portable and wearable devices,as well as for human health care.展开更多
Achieving excellent electromagnetic interference(EMI)shielding effectiveness(SE)in high rare earth(RE)-content Mg alloys is currently a significant technical challenge.This work systematically investigated the effects...Achieving excellent electromagnetic interference(EMI)shielding effectiveness(SE)in high rare earth(RE)-content Mg alloys is currently a significant technical challenge.This work systematically investigated the effects of different Nd elements on the electrical conductivity and EMI SE of Mg-12Gd-3Y-xNd alloy by adding Nd elements to the high RE content Mg-12Gd-3Y alloy,followed by a combined process of hot rolling and aging(R-A).The results indicate that the addition of Nd elements leads to reduced solid solubility of Gd and Y,resulting in a large amount of precipitation.The Mg-12Gd-3Y-2.0Nd alloy has the optimum EMI SE after 63%R-A treatment,reaching 88-118 dB at 30-1500 MHz.The Mg-12Gd-3Y-xNd alloy has acicular and granular forms of the Mg5(Gd,Y,Nd)(abbreviated as Mg5RE)phase after R-A treatment.The granular Mg5RE phase gradually breaks up and refines into more minor scales with increasing rolling reduction and is diffusely distributed in the matrix.The acicular Mg5RE phase is densely arranged,with cross-distribution in some areas.The cross-distributed acicular Mg5RE phase,the delicate granular Mg5RE phase,and the denseβ′phase provide more interfaces for reflecting electromagnetic waves and increase the multiple reflection loss of incident electromagnetic waves.In addition,the Mg-12Gd-3Y-xNd alloy deflects most of the c-axis of the grains parallel to the normal direction(ND)as the rolling reduction increases,making the impedance difference between the plate surface and air larger.The increased impedance makes the material reflect more loss to incident electromagnetic waves.The combined use of these two leads to an excellent EMI SE of Mg-12Gd-3Y-xNd with high RE content after R-A treatment.展开更多
In this article, hybrid fillers with different dimensions, namely, 2-dimensional（2-D） expanded graphite（EG） and 1-dimensional（1-D） multi-walled carbon nanotubes（CNTs）, were added to aromatic nylon MXD6 matrix ...In this article, hybrid fillers with different dimensions, namely, 2-dimensional（2-D） expanded graphite（EG） and 1-dimensional（1-D） multi-walled carbon nanotubes（CNTs）, were added to aromatic nylon MXD6 matrix via melt-blending, to enhance its thermal and electrical conductivity as well as electromagnetic interference shielding effectiveness（EMI SE）. For ternary composites of MXD6/EG/CNTs, the electrical conductivity reaches up nine orders of magnitude higher compared to that of the neat MXD6 sample, which turned the polymer-based composites from an insulator to a conductor, and the thermal conductivity has been enhanced by 477% compared with that of neat MXD6 sample. Meanwhile, the EMI SE of ternary composite reaches ~50 d B at the overall filler loading of only 18 wt%. This work can provide guidance for the preparation of polymer composites with excellent thermal and electrical conductivity via using hybrid filler.展开更多
通过环氧树脂(EP)泡沫泡孔壁和泡孔框架中均匀分布的镀镍碳纤维(NCCF)和乙炔炭黑(ACET)构建有效的导电网络,成功制备了逾渗值仅为0.81%(体积分数)的EP/NCCF/ACET复合导电泡沫。采用化学镀的方法制备得到了NCCF,将NCCF和ACET分散在EP中,...通过环氧树脂(EP)泡沫泡孔壁和泡孔框架中均匀分布的镀镍碳纤维(NCCF)和乙炔炭黑(ACET)构建有效的导电网络,成功制备了逾渗值仅为0.81%(体积分数)的EP/NCCF/ACET复合导电泡沫。采用化学镀的方法制备得到了NCCF,将NCCF和ACET分散在EP中,作为不同维度的导电填料,两者在基体中具有协同效应,利用化学发泡法制备了轻质的EP/NCCF/ACET复合导电泡沫。通过扫描电子显微镜及电性能、电磁屏蔽性能、力学性能等测试对EP复合导电泡沫进行表征。结果表明,NCCF和ACET在EP泡沫基体中均匀分散,NCCF在泡孔框架中相互搭接,ACET在NCCF间起到桥接作用,两者共同作用形成连续的导电网络。两种填料协同作用能显著提高材料的电性能和电磁屏蔽性能,电导率最高可以达到13.14 S/m,平均屏蔽效能可达到20.7 d B。同时,在一定含量范围内,NCCF的加入能够提升泡沫材料的拉伸性能。展开更多
基金L.Z.and C.L.contributed equally to this work.This work was supported by the Natural Science Foundation of China(No.51903001)Anhui Province International Science and Technology Cooperation Program(No.1804b06020360)+2 种基金Anhui Province International Cooperation Research Center of Textile Structure Composites(No.2021ACTC07)Research Funds of Anhui Polytechnic University(No.Xjky2020041)S.C.T.acknowledges the financial support from MOE AcRF2(R-284-000-217-112).
文摘Durable electromagnetic interference(EMI)shielding is highly desired,as electromagnetic pollution is a great concern for electronics’stable performance and human health.Although a superhydrophobic surface can extend the service lifespan of EMI shielding materials,degradation of its protection capability and insufficient self-healing are troublesome issues due to unavoidable physical/chemical damages under long-term application conditions.Here,we report,for the first time,an instantaneously self-healing approach via microwave heating to achieve durable shielding performance.First,a hydrophobic 1H,1H,2H,2H-perfluorooctyltriethoxysilane(POTS)layer was coated on a polypyrrole(PPy)-modified fabric(PPy@POTS),enabling protection against the invasion of water,salt solution,and corrosive acidic and basic solutions.Moreover,after being damaged,the POTS layer can,for the first time,be instantaneously self-healed via microwave heating for a very short time,i.e.,4 s,benefiting from the intense thermal energy generated by PPy under electromagnetic wave radiation.This self-healing ability is also repeatable even after intentionally severe plasma etching,which highlights the great potential to achieve robust and durable EMI shielding applications.Significantly,this approach can be extended to other EMI shielding materials where heat is a triggering stimulus for healing thin protection layers.We envision that this work could provide insights into fabricating EMI shielding materials with durable performance for portable and wearable devices,as well as for human health care.
基金financially supported by the National Key R&D Program of China(2021YFB3701100)the National Natural Science Foundation of China(52225101 and 52171103)the Fundamental Research Funds for the Central Universities(2020CDJDPT001).
文摘Achieving excellent electromagnetic interference(EMI)shielding effectiveness(SE)in high rare earth(RE)-content Mg alloys is currently a significant technical challenge.This work systematically investigated the effects of different Nd elements on the electrical conductivity and EMI SE of Mg-12Gd-3Y-xNd alloy by adding Nd elements to the high RE content Mg-12Gd-3Y alloy,followed by a combined process of hot rolling and aging(R-A).The results indicate that the addition of Nd elements leads to reduced solid solubility of Gd and Y,resulting in a large amount of precipitation.The Mg-12Gd-3Y-2.0Nd alloy has the optimum EMI SE after 63%R-A treatment,reaching 88-118 dB at 30-1500 MHz.The Mg-12Gd-3Y-xNd alloy has acicular and granular forms of the Mg5(Gd,Y,Nd)(abbreviated as Mg5RE)phase after R-A treatment.The granular Mg5RE phase gradually breaks up and refines into more minor scales with increasing rolling reduction and is diffusely distributed in the matrix.The acicular Mg5RE phase is densely arranged,with cross-distribution in some areas.The cross-distributed acicular Mg5RE phase,the delicate granular Mg5RE phase,and the denseβ′phase provide more interfaces for reflecting electromagnetic waves and increase the multiple reflection loss of incident electromagnetic waves.In addition,the Mg-12Gd-3Y-xNd alloy deflects most of the c-axis of the grains parallel to the normal direction(ND)as the rolling reduction increases,making the impedance difference between the plate surface and air larger.The increased impedance makes the material reflect more loss to incident electromagnetic waves.The combined use of these two leads to an excellent EMI SE of Mg-12Gd-3Y-xNd with high RE content after R-A treatment.
基金financially supported by the National Natural Science Foundation of China(Nos.21274095 and 51573102)
文摘In this article, hybrid fillers with different dimensions, namely, 2-dimensional（2-D） expanded graphite（EG） and 1-dimensional（1-D） multi-walled carbon nanotubes（CNTs）, were added to aromatic nylon MXD6 matrix via melt-blending, to enhance its thermal and electrical conductivity as well as electromagnetic interference shielding effectiveness（EMI SE）. For ternary composites of MXD6/EG/CNTs, the electrical conductivity reaches up nine orders of magnitude higher compared to that of the neat MXD6 sample, which turned the polymer-based composites from an insulator to a conductor, and the thermal conductivity has been enhanced by 477% compared with that of neat MXD6 sample. Meanwhile, the EMI SE of ternary composite reaches ~50 d B at the overall filler loading of only 18 wt%. This work can provide guidance for the preparation of polymer composites with excellent thermal and electrical conductivity via using hybrid filler.
文摘通过环氧树脂(EP)泡沫泡孔壁和泡孔框架中均匀分布的镀镍碳纤维(NCCF)和乙炔炭黑(ACET)构建有效的导电网络,成功制备了逾渗值仅为0.81%(体积分数)的EP/NCCF/ACET复合导电泡沫。采用化学镀的方法制备得到了NCCF,将NCCF和ACET分散在EP中,作为不同维度的导电填料,两者在基体中具有协同效应,利用化学发泡法制备了轻质的EP/NCCF/ACET复合导电泡沫。通过扫描电子显微镜及电性能、电磁屏蔽性能、力学性能等测试对EP复合导电泡沫进行表征。结果表明,NCCF和ACET在EP泡沫基体中均匀分散,NCCF在泡孔框架中相互搭接,ACET在NCCF间起到桥接作用,两者共同作用形成连续的导电网络。两种填料协同作用能显著提高材料的电性能和电磁屏蔽性能,电导率最高可以达到13.14 S/m,平均屏蔽效能可达到20.7 d B。同时,在一定含量范围内,NCCF的加入能够提升泡沫材料的拉伸性能。
