聚偏氟乙烯/导电炭黑填充聚偏氟乙烯层状复合材料的电磁屏蔽性能研究

Investigation on the Electromagnetic Shielding Properties of PVDF/Carbon Black-filled PVDF Laminate Composites

以聚偏氟乙烯(PVDF)为基体、导电炭黑(CB)为填料,制备了PVDF/CB复合材料。研究了导电粒子含量、PVDF/CB与纯PVDF层层叠合等因素对PVDF电磁屏蔽效能的影响。结果显示,随着CB含量增加,PVDF/CB复合体系的屏蔽效能(SE)逐渐升高。根据电性能测试结果,导电粒子越多,体系的电阻率越低,因而对电磁波的反射作用增强,导致SE值提高。将质量分数为15%的CB填充的PVDF与纯PVDF按不同层厚比叠合成2层样品后进行电磁屏蔽测试发现,随着PVDF/CB层层厚增加,PVDF层层厚降低,层状体系的电磁屏蔽性能逐渐提高。与具有相同层厚度、相同CB含量的PVDF/CB复合体系相比,层状体系的屏蔽效果明显高于前者。与测试结果相比,理论曲线的趋势基本一致,但测试曲线中出现屏蔽峰的频率更低。分析认为,当电磁波作用在层状体系上时,PVDF/CB层中的CB粒子可能会影响到相邻PVDF层中的电荷移动,使其达到最大吸收需要更长的时间,这为宽频电磁屏蔽材料的制备提供了思路。

The polyvinylidene fluoride/carbon black （PVDF/CB） composites were fabricated in this work.The effects of CB particle composition and layered assembly of PVDF and PVDF/CB on the electromagnetic shielding properties had been performed.The results indicated that the shielding effectiveness （SE） was gradually enhanced with increasing CB loadings in PVDF/CB composites.According to the measured resistivity,the specimen filled with more conductive particles had a lower volume resistivity,so that the SE value was enhanced by reflecting more electromagnetic waves.When the PVDF/CB filled with 15wt% CB was combined with pure PVDF forming 2-layer laminates,the electromagnetic shielding properties were gradually improved with increasing the thickness ratio of PVDF/CB to pure PVDF layers.By filling with the same content of CB particles,it was found that the SE value of the laminate composite was distinctly larger than that of the conventional PVDF/CB composite.The tendency of experimental shielding curve was in accordance with the theoretical predicted curve.However,the frequency of shielding peak was lower than the latter.It was considered that when the electromagnetic waves were performed on the laminate composites,the CB particles in the PVDF/CB layer might affect the mobile of charges in the adjacent PVDF layers,so that more time for approaching to the maximum absorption was required.This provided a potential route to design electromagnetic shielding materials with broadband.