碳系导电填料性质对PVB基功能薄膜结构及电磁屏蔽效能的影响

Influence of Carbon-based Conductive Filler’s Properties on the ElectromagneticShielding Effectiveness of PVB/Filler Functional Composite Films

中文关键词: 复合材料薄膜 碳系导电填料 分布结构 电磁屏蔽

英文关键词: composite film, carbon-based conductive filler, distribution structure, electromagnetic shielding

中文摘要:

      分别以形状和电导率不同的石墨、镀镍石墨和镀银碳纤维为功能填料,采用溶液流延法制备了聚乙烯醇缩丁醛基导电薄膜,并对薄膜的微观结构和电学性能进行了研究。结果表明:填料性质(包括形状、密度和电导率)对复合材料的分布结构和电学性能有重要影响,纤维状的填料更容易搭接成导电网络。石墨和镀银碳纤维填充体系中,填料在聚合物基体内部分布基本均匀；而镀镍石墨填充体系中,填料在聚合物基体内部形成了梯度分布。不同的分布状态导致材料的导电性能在薄膜的上下表面产生差异并对复合材料的电磁屏蔽效能产生影响。在同等体积含量下,复合材料的电磁屏蔽效能主要受材料电导率的影响,三种复合材料中,镀银碳纤维填充体系的屏蔽效能最高,镀镍石墨填充体系次之,石墨填充体系最低。

英文摘要:

      The present paper mainly concerns the influence of carbon-based conductive filler’s properties on the electromagne-tic shielding effectiveness of polyvinyl butyral (PVB)/filler functional composite films. Three kinds of fillers, i.e., graphite, nickel coated graphite and silver coated carbon fiber, each of which differs in conductivity and geometrical shape, were selected as functional fillers to modify PVB resin, respectively, and consequently form a series of PVB/filler functional composite films by solution casting method. Our experiment confirmed the significant influences of the filler’s properties, including geometrical shape, density and conductivity on the microstructure and electrical performance of the composites. It was found that fibrous filler more easily lap into a conductive network. Scanning electron microscope (SEM) observation revealed that fillers were distributed more uniformly in PVB matrix in both the graphite and silver coated carbon fiber composite system. However, the nickel coated graphite formed a gradient distribution inside the composite. The difference in distribution structure leads to the discrepancy of the electrically conductive performance between the top and bottom surface of the film and brings varying electromagnetic shielding effectiveness. Under the same filler volume content, the electromagnetic shielding effectiveness of the composite mainly depends on the conductivity of the material. Among the three composites, the PVB/silver coated carbon fiber system and the PVB/graphite system have the highest and the lowest electromagnetic shielding effectiveness, respectively, and the PVB/nickel coated graphite holds a medium between the former two composites.