层状PPGr/PP复合材料的结构和电磁屏蔽性能

利用共挤出设备,制备了导电层(石墨填充聚丙烯PPGr)和绝缘层(聚丙烯PP)叠合的层状复合物,同时制备了PPGr普通共混物。比较了层状材料与普通共混材料在结构形态、电学性能、力学性能和电磁屏蔽性能方面的差异。研究发现,普通共混物电阻率为2.04×103Ω.cm时,在低频区(500 MHz~2 GHz)和中间频段区(2 GHz~18 GHz)内的最大屏蔽值都为34dB,而层状材料电阻率为2.79×105Ω.cm时,在上述频率区间的屏蔽效果分别达到49dB和56dB。力学性能测试表明层状材料的断裂伸长率和拉伸强度也优于普通共混材料。文中提出了层状复合物中电磁波的内部多重反射机理来解释这一实验现象。

Structure and Electromagnetic Interference Shielding Properties of Microlayered PPGr/PP Composites

Polypropylene with a graphite filler(PPGr)/ polypropylene(PP) composites with superimposed conductive layer and insulated layer were prepared by the co-extrusion equipment,and the PPGr normal blend was also prepared.The structure and morphology,conductive properties,mechanical properties and electromagnetic interference(EMI) shielding performance of layer-structure material and normal blend were compared.It is found that the maximal shielding value of normal composites is 34 dB in both low frequency region(500MHz~2GHz) and middle frequency range(2GHz~18GHz) when its volume resistivity is 2.04×103 Ω·cm.While the corresponding shielding value for layer-structure composites are 49dB and 56dB respectively when its volume resistivity reaches up to 2.79×105 Ω·cm.The mechanical measurement indicates that the elongation at break and tensile strength of layer-structure composites are also better than that of the normal blend.The inner multiple reflection mechanism is proposed to explain the experimental phenomenon.