聚苯胺性状及其含量对镍粉/聚苯胺涂层屏蔽性能的影响

系统分析了金属粉末/聚苯胺复合电磁屏蔽材料中导电聚苯胺的性状,体积分数对微观结构和电磁屏蔽效能的影响.从二次掺杂的导电聚苯胺的电磁性能讨论了聚苯胺对电磁屏蔽效能的贡献.研究了二次掺杂聚苯胺性状对电磁屏蔽涂层微观结构形貌以及与金属粉末的复合效应对电磁屏蔽效能的贡献.研究的结果表明导电聚苯胺的加入有利于增加电磁屏蔽材料对于高频电磁波的电磁屏蔽效能,但是对低频部分的电磁波的屏蔽效能与纯金属粉末电磁屏蔽材料相比有所降低,这可能是由于聚苯胺加入导致的导电组分分布不均匀所引起的.实验结果表明胶状体聚苯胺和粉末状聚苯胺在电磁屏蔽涂料基体树脂中具有完全不同的形态,分析了对电磁屏蔽效能的影响.     

合成纤维复合夹层屏蔽结构改性及其电磁特性研究

提出具有复合介质夹层屏蔽结构模型的设想,利用铜箔-聚四氟乙烯为原材料,设计了单层屏蔽结构与复合夹层屏蔽结构的对比实验,测试了复合夹层屏蔽结构的电磁屏蔽效能增量,并用Ватолцн多层电磁屏蔽理论公式进行了验证。具有复合夹层屏蔽结构材料的电磁屏蔽效能明显优于单层屏蔽结构材料的电磁屏蔽效能。继而以涤纶无纺布、锦纶合成纤维为研究对象,采用电化学改性的方法,制备了具有复合夹层屏蔽结构的柔性电磁屏蔽材料。结果表明,通过对研究对象的选择和优化电化学改性的工艺,可以制备出1 MHz~1000 MHz入射电磁波频段范围内,满足不同要求的合成纤维复合夹层屏蔽结构改性材料,其SE值最高可达98 dB。     

超疏水电磁屏蔽材料的制备及研究进展

超疏水电磁屏蔽材料以其自清洁、抗污、防粘附、防腐、防电磁辐射等特性具有广泛的应用前景。介绍了超疏水电磁屏蔽材料的制备原理，阐述了基于纳米金属、碳基导电复合材料、导电聚合物的超疏水电磁屏蔽功能材料的制备方法及其应用，分析了超疏水电磁屏蔽材料开发所存在的问题，并对具有优异电磁屏蔽性能的超疏水多功能材料的开发进行了展望。     

电磁屏蔽聚合物复合泡沫材料的制备及研究进展

综述了聚合物复合泡沫材料的最新应用进展，详细介绍了聚合物复合泡沫材料在电磁屏蔽领域的研究现状。首先概述了聚合物复合泡沫材料的不同制备方法，重点分析了不同填料、孔隙结构、材料厚度对电磁屏蔽性能的影响。最后介绍了聚合物复合泡沫材料在电磁屏蔽材料领域中的应用，并对其未来发展进行了展望。     

电磁屏蔽材料中聚苯胺对屏蔽效能的影响及机理

金属材料与导电聚苯胺复合形成屏蔽组分有效提高了复合电磁屏蔽材料的高频电磁屏蔽效能,从而扩展了屏蔽材料的屏蔽带宽.以金属Ni粉/导电聚苯胺复合屏蔽组分为例,分析了在复合电磁屏蔽材料中聚苯胺的对屏蔽效能的贡献及作用机理.结果表明聚苯胺的加入与基体树脂相溶形成基体导电网络,有效阻碍了高频电磁波的穿透,可能是提高高频效能的主要原因.     

单壁碳纳米管无纺布/环氧树脂复合材料的电磁屏蔽性能

采用一种导电材料预制体-单壁碳纳米管(Single-wall carbon nanotube,SWCNT)无纺布与环氧树脂复合制备了电磁屏蔽复合材料,并对所制复合材料的电磁屏蔽性能进行了表征。结果表明:所制复合材料对电磁波的屏蔽效率随SWCNT无纺布厚度的增加而增加。在较低的SWCNT无纺布填加量下所制复合材料可以实现对低频电磁波较高的屏蔽效率。不同于填加粉体导电材料所制电磁屏蔽复合材料,作为导电材料预制体使用的SWCNT无纺布是一个独立的整体导电薄膜,可以直接引入到基体当中,不存在分散问题。并且通过简单的导电预制体多层叠加的方式即可实现复合材料更高的屏蔽效率。     

静电纺丝技术制备复合纳米纤维电磁屏蔽及吸波材料的研究进展

随着信息时代的到来,电磁波的泄漏给人类健康带来了严重的危害,因此,高性能电磁防护材料的设计迫在眉睫。静电纺丝技术制备的复合纳米纤维具有质量轻、成本低、比表面积大、易加工和物理化学性能稳定等优点,是近年来高性能电磁屏蔽及吸波材料研究的热点。本文首先介绍了电磁屏蔽及吸波的基本原理,并结合国内外研究现状,将市场上应用广泛的电磁屏蔽及吸波材料系统的分成了金属及金属氧化物、碳材料、导电聚合物和过渡金属碳化物4类,并进行了详细了介绍。同时,综述了各种填料对电磁屏蔽及吸波性能的影响及目前正面临的问题。     

电磁屏蔽材料的研究进展

随着电磁环境污染的日益严重,探索高效的电磁屏蔽材料已成为材料研究中亟需解决的问题。介绍了电磁屏蔽材料的屏蔽机理和常用的测试屏蔽效能的方法;按照金属和导电聚合物电磁屏蔽材料两大类,综述了近些年电磁屏蔽材料制备与应用领域方面的研究;并对电磁屏蔽材料的发展前景进行展望。     

化学镀制备电磁屏蔽用导电复合填料的研究进展

介绍了化学镀的基本原理和主要特点,重点阐述了以金属、无机非金属、聚合物等粉料为基体,采用化学镀技术制备具有不同粒度、密度、长径比、导电性、电磁屏蔽效能和抗氧化性的电磁屏蔽用金属包覆型导电复合填料的国内外研究现状和进展,分析比较了这3类电磁屏蔽用导电复合填料的优缺点,指出其目前还存在电磁阻抗不匹配、电磁综合性能不高和表面性质差异过大的主要问题,建议今后还需进一步研究复合填料组成、化学镀配方和工艺等,以研制出性价比更高的电磁屏蔽用复合填料。     

电磁屏蔽涂料制备的新进展

从导电填料的种类、复合工艺及其对涂料导电性能的影响等方面,综述了近五年来掺和型电磁屏蔽涂料制备的最新进展.金属、石墨和复合导电填料等都具有良好的导电性,尤以复合导电填料应用效果最好;原位插层复(聚)合法是制备电磁屏蔽材料的一种较新复合工艺,可获得低逾渗阀值和高导电率,具有良好的发展前景;同时,导电填料的用量、性状、分散效果以及分散助剂等对电磁屏蔽涂料的导电性能都有较大影响.     

Highly Stretchable Polymer Composite with Strain-Enhanced Electromagnetic Interference Shielding Effectiveness

Polymer composites with electrically conductive fillers have been developed as mechanically flexible, easily processable electromagnetic interference (EMI) shielding materials. Although there are a few elastomeric composites with nanostructured silvers and carbon nanotubes showing moderate stretchability, their EMI shielding effectiveness (SE) deteriorates consistently with stretching. Here, a highly stretchable polymer composite embedded with a three-dimensional (3D) liquid-metal (LM) network exhibiting substantial increases of EMI SE when stretched is reported, which matches the EMI SE of metallic plates over an exceptionally broad frequency range of 2.65–40 GHz. The electrical conductivities achieved in the 3D LM composite are among the state-of-the-art in stretchable conductors under large mechanical deformations. With skin-like elastic compliance and toughness, the material provides a route to meet the demands for emerging soft and human-friendly electronics.     

Graphene foam/carbon nanotube/poly(dimethyl siloxane) composites for exceptional microwave shielding

Highly porous poly(dimethyl siloxane) (PDMS) composites containing cellular-structured microscale graphene foams (GFs) and conductive nanoscale carbon nanotubes (CNTs) are fabricated. The unique three-dimensional, multi-scale hybrid composites with inherent percolation and a high porosity of 90.8% present a remarkable electromagnetic interference shielding effectiveness (EMI SE) of ∼75 dB, a 200% enhancement against 25 dB of the composites made from GFs alone with the same graphene content and porosity. The corresponding specific EMI SE measured against the composite density is 833 dB cm³/g. These values are among the highest for all carbon filler/polymer composites reported thus far. Significant synergy arises from the hybrid reinforcement structure of the composites: the GFs drive the incident microwaves to be attenuated by dissipation of the currents induced by electromagnetic fields, while the CNTs greatly enhance the dissipation of surface currents by expanding the conductive networks and introducing numerous interfaces with the matrix.     

碳系填充型电磁屏蔽材料的研究进展

填充型电磁屏蔽材料在电磁屏蔽领域有着广阔的应用前景,而碳填料具有来源广、质量轻、成本低、导电性良好等优点,以其作为导电填料的填充型电磁屏蔽材料因具有较好的综合性能而受到越来越多的关注.对近年来国内外碳系填充型电磁屏蔽材料的发展情况进行了综合评述,着重介绍了碳系填充型电磁屏蔽材料的导电机理、填充方法、分类、掺杂及影响其屏蔽性能的主要因素.     

Interface sintering engineered superhydrophobic and durable nanofiber composite for high-performance electromagnetic interference shielding

Electrically conductive fibric composites(CFCs)have been widely used as electromagnetic interference(EMI)shielding materials;however,it is still difficult to ac...     

Polymer/carbon based composites as electromagnetic interference (EMI) shielding materials

The extensive development of electronic systems and telecommunications has lead to major concerns regarding electromagnetic pollution. Motivated by environmental questions and by a wide variety of applications, the quest for materials with high efficiency to mitigate electromagnetic interferences (EMI) pollution has become a mainstream field of research. This paper reviews the state-of-the-art research in the design and characterization of polymer/carbon based composites as EMI shielding materials. After a brief introduction, in Section 1, the electromagnetic theory will be briefly discussed in Section 2 setting the foundations of the strategies to be employed to design efficient EMI shielding materials. These materials will be classified in the next section by the type of carbon fillers, involving carbon black, carbon fiber, carbon nanotubes and graphene. The importance of the dispersion method into the polymer matrix (melt-blending, solution processing, etc.) on the final material properties will be discussed. The combination of carbon fillers with other constituents such as metallic nanoparticles or conductive polymers will be the topic of Section 4. The final section will address advanced complex architectures that are currently studied to improve the performances of EMI materials and, in some cases, to impart additional properties such as thermal management and mechanical resistance. In all these studies, we will discuss the efficiency of the composites/devices to absorb and/or reflect the EMI radiation.     

Development of high performance EMI shielding material from EVA,NBR, and their blends: effect of carbon black structure

The conductive composites were prepared using two different types of conductive black (Conductex and Printex XE2) filled in matrices like EVA and NBR and their different blends. The electromagnetic interference shielding effectiveness (EMI SE) of all composites was measured in the X band frequency range 8–12 GHz. Both conductivity and EMI SE increase with filler loading. However, Printex black shows higher conductivity and better EMI SE at the same loading compared to Conductex black, and this can be used as a material having high EMI shielding effectiveness value. The conductivity of different blends with same filler loading generally found to increase slightly with the increase in NBR concentration. However, EMI SE has some dependency on blend composition. EMI SE increases linearly with thickness of the sample. EMI SE versus conductivity yields two master curves for two different fillers. EMI SE depends on formation of closed packed conductive network in insulating matrix, and Printex black is better than Conductex black in this respect. Some of the composites show appreciably high EMI SE (>45 dB).     

Electromagnetic interference shielding characteristics of carbon nanofiber-polymer composites

Electromagnetic interference (EMI) shielding characteristics of carbon nanofiber-polystyrene composites were investigated in the frequency range of 12.4-18 GHz (Ku-band). It was observed that the shielding effectiveness of such composites was frequency independent, and increased with increasing carbon nanofiber loading within Ku-band. The experimental data exhibited that the shielding effectiveness of the polymer composite containing 20 wt% carbon nanofibers could reach more than 36 dB in the measured frequency region, indicating such composites can be applied to the potential EMI shielding materials. In addition, the results showed that the contribution of reflection to the EMI shielding effectiveness was much larger than that of absorption, implying the primary EMI shielding mechanism of such composites was reflection of electromagnetic radiation within Ku-band.     

三维碳化硅纳米线增强碳化硅陶瓷基复合材料的电磁屏蔽性能

碳化硅纳米线具有优异的电磁吸收性能, 三维网络结构可以更好地使电磁波在空间内被多次反射和吸收。通过抽滤的方法制备得到体积分数20%交错排列的碳化硅纳米线网络预制体。然后采用化学气相渗透工艺制备热解炭界面和碳化硅基体, 并通过化学气相渗透和前驱体浸渍热解工艺得到致密的SiCNWs/SiC陶瓷基复合材料。甲烷和三氯甲基硅烷分别是热解炭和碳化硅的前驱体, 随着热解碳质量分数从21.3%增加到29.5%, 多孔SiCNWs预制体电磁屏蔽效率均值在8~12 GHz (X)波段从9.2 dB增加到64.1 dB。质量增重13%的热解碳界面修饰的SiCNWs/SiC陶瓷基复合材料在X波段平均电磁屏蔽效率达到37.8 dB电磁屏蔽性能。结果显示, SiCNWs/SiC陶瓷基复合材料在新一代军事电磁屏蔽材料中具有潜在应用前景。     

Porous composites coated with hybrid nano carbon materials perform excellent electromagnetic interference shielding

This work reported preparation of porous composites using a simple dip-coating method, and the fabricated composites containing hybrid carbon nanomaterials performed excellent electromagnetic interference (EMI) shielding properties. A commercial sponge was coated with silver nanoparticles before being dip-coated with graphene (GP)/ink, multi-wall carbon nanotubes (MWCNTs)/ink, or hybrid GP/MWCNTs/ink to form Ag/carbon nanomaterial hybrid composites, and then the composites were subjected to EMI measurements in the frequency range of 0.45–1.5 GHz. For comparison, the sponges without Ag nanoparticle coating were also prepared. Herein, we found an insignificant difference in EMI SE among the porous composites without Ag nanoparticle coating, and the maximum values of approximately 14.4 dB was attained. Interestingly, the hybrid composites with Ag nanoparticle coating exhibited maximum EMI shielding of 24.33 dB. Due to their porous structure, the EMI SE measurements showed that reflection dominates the EMI SE for all the sponge composites studied in this work.