Conductive sheets consisting of copper fibers,urea formaldehyde resins and decorative papers were prepared by hot pressing.The results showed that the sheet resistance of composites had mutations with the increasing o...Conductive sheets consisting of copper fibers,urea formaldehyde resins and decorative papers were prepared by hot pressing.The results showed that the sheet resistance of composites had mutations with the increasing of copper fiber filling ratio.The sheets exhibited percolation threshold effect.The threshold of sheets filled with 5 mm copper fibers was about 16% and the threshold of sheets filled with 10 mm or 15 mm copper fibers were about 8.7%.Meanwhile,the sheets showed piezoresistive characteristics and the conductive structure of sheets have been gradually developped into "three-dimensional conductive network" from "two-dimensional conductive network".Moreover,the length of copper fibers showed strong effects to the conductivity.Under the same fiber filling ratio,the larger length of fiber was,the higher conductivity and the lower percolation threshold could be.展开更多
为探究不锈钢纤维长度与填充量对导电膜片导电性能与电磁屏蔽性能的影响,将不锈钢纤维均匀地铺撒在涂有脲醛树脂和丙烯酸树脂的表层纸上热压,制备具有电磁屏蔽功能的不锈钢纤维填充导电膜片。首先通过微观结构表征,分析不锈钢纤维在导...为探究不锈钢纤维长度与填充量对导电膜片导电性能与电磁屏蔽性能的影响,将不锈钢纤维均匀地铺撒在涂有脲醛树脂和丙烯酸树脂的表层纸上热压,制备具有电磁屏蔽功能的不锈钢纤维填充导电膜片。首先通过微观结构表征,分析不锈钢纤维在导电膜片平面和断面内的搭接状况;然后采用四电极法与同轴线法测试导电膜片的体积电阻率及电磁屏蔽效能;最后通过理论模拟探究不锈钢纤维填充导电膜片的电磁屏蔽机理。结果表明：1）随着不锈钢纤维填充量的增加,导电膜片平面和断面内不锈钢纤维之间交叉排列的混乱程度不断增加,并以随机排列的形式相互交织形成了有效的＂三维导电网络＂。2）随着不锈钢纤维长度和填充量的不断增加,导电膜片的体积电阻率逐渐减小,而其电磁屏蔽效能逐渐增大。3）不锈钢纤维的填充量、导电膜片厚度对导电膜片的导电性能影响显著。4）当不锈钢纤维长度为15 mm、填充量为250 g/m2时,导电膜片的体积电阻率降低为6.493×10-3Ω·cm,电磁屏蔽效能为37.77-51.42 d B,达到中等屏蔽效果,适用于对电磁兼容要求较高的场合。5）理论模拟结果表明,吸收损耗在导电膜片对电磁辐射的屏蔽效果中占有很大的比重,导电膜片表现出了很好的吸波特性。展开更多
文摘Conductive sheets consisting of copper fibers,urea formaldehyde resins and decorative papers were prepared by hot pressing.The results showed that the sheet resistance of composites had mutations with the increasing of copper fiber filling ratio.The sheets exhibited percolation threshold effect.The threshold of sheets filled with 5 mm copper fibers was about 16% and the threshold of sheets filled with 10 mm or 15 mm copper fibers were about 8.7%.Meanwhile,the sheets showed piezoresistive characteristics and the conductive structure of sheets have been gradually developped into "three-dimensional conductive network" from "two-dimensional conductive network".Moreover,the length of copper fibers showed strong effects to the conductivity.Under the same fiber filling ratio,the larger length of fiber was,the higher conductivity and the lower percolation threshold could be.
文摘为探究不锈钢纤维长度与填充量对导电膜片导电性能与电磁屏蔽性能的影响,将不锈钢纤维均匀地铺撒在涂有脲醛树脂和丙烯酸树脂的表层纸上热压,制备具有电磁屏蔽功能的不锈钢纤维填充导电膜片。首先通过微观结构表征,分析不锈钢纤维在导电膜片平面和断面内的搭接状况;然后采用四电极法与同轴线法测试导电膜片的体积电阻率及电磁屏蔽效能;最后通过理论模拟探究不锈钢纤维填充导电膜片的电磁屏蔽机理。结果表明：1）随着不锈钢纤维填充量的增加,导电膜片平面和断面内不锈钢纤维之间交叉排列的混乱程度不断增加,并以随机排列的形式相互交织形成了有效的＂三维导电网络＂。2）随着不锈钢纤维长度和填充量的不断增加,导电膜片的体积电阻率逐渐减小,而其电磁屏蔽效能逐渐增大。3）不锈钢纤维的填充量、导电膜片厚度对导电膜片的导电性能影响显著。4）当不锈钢纤维长度为15 mm、填充量为250 g/m2时,导电膜片的体积电阻率降低为6.493×10-3Ω·cm,电磁屏蔽效能为37.77-51.42 d B,达到中等屏蔽效果,适用于对电磁兼容要求较高的场合。5）理论模拟结果表明,吸收损耗在导电膜片对电磁辐射的屏蔽效果中占有很大的比重,导电膜片表现出了很好的吸波特性。
