| With the rapid development of modern technology,the problem of electromagnetic interference is becoming more and more serious.In recent years,electromagnetic shielding materials have been developing towards the direction of"thin,light,wide,strong"and corrosion resistance.Many scholars have developed various kinds of electromagnetic shielding materials with excellent properties.Conductive polymer composites are valuable electromagnetic shielding materials at present,however,there are still many challenges in improving the electromagnetic shielding performance of conductive polymer composites.In this paper,through a feasible preparation process,a series of conductive polymer composites with different electromagnetic shielding effectiveness were designed by using PVDF?Poly?vinylidene fluoride??as matrix,CNT?Carbon nanotube?and GnP?Graphene plate?as filler.?1?PVDF/CNT composites were prepared by solution spinning and hot pressing method.The introduction of one-dimensional CNT of conducting filler can change the conductivity of the composites,thus affecting the electromagnetic shielding performance.When the CNT content increased from 0.5 wt%to 10 wt%,the conductivity of PVDF/CNT composites increased from 5.7×10-6 S/cm to 0.05 S/cm,and the electromagnetic shielding efficiency increased from 2 dB to 21.1 dB,which can meet the need of commercial application.The shielding mechanism of PVDF/CNT composites is based on absorption loss and assisted by reflection loss.The PVDF/CNT composites prepared in this paper also possess hydrophobic feature.?2?PVDF/GnP composites were prepared by solution spinning and hot pressing method.GnP is non-magnetic filler,which affects the shielding property of composites mainly through conductivity.We studied the influence of GnP content on the conductivity and electromagnetic shielding performance of the composites.When GnP content increased from 10 wt%to 80 wt%,the conductivity of PVDF/GnP composites increased from 5.5×10-4 S/cm to 0.11 S/cm,and the electromagnetic shielding efficiency increased from 5.7 dB to 22.4 dB.In this paper,DMF was used to treat the PVDF/GnP composites,after dissolving part of PVDF,the electromagnetic shielding efficiency of the composites were changed.?3?PVDF/CNT/GnP composites were also prepared by solution spinning and hot pressing.In the experiment,the content of CNT was controlled at 5 wt%,with the increase of GnP,a large amount of interface loss,polarization loss and dielectric loss were generated in the composites due to the common effect of CNT and GnP.The shielding efficiency of PVDF/CNT/GnP composites has been increasing and was better than that of PVDF/GnP composites with the same concentration of GnP.When GnP content was 80 wt%,the conductivity and the electromagnetic shielding efficiency of PVDF/CNT/GnP composites reached 0.35 S/cm,25.4 dB respectively.In addition,we studied the effect of sample thickness on electromagnetic shielding performance.When GnP content was 60 wt%,the electromagnetic shielding efficiency of PVDF/CNT/GnP composites with 1 layer,2 layers and 3 layers were 19.9 dB,22.3 dB and 26.5 dB,respectively.The hydrophobic attributes of PVDF/CNT/GnP composites was also studied,and it was found that the hydrophobic properties increased with the increase of GnP.According to the results in this paper,through simple solution spinning and hot pressing method,high performance composite fabric can be prepared under lower filler content to meet application requirements.If different materials were compounded,it would be more beneficial to improve the electromagnetic shielding performance due to synergistic effect between different materials.These results might provide some theoretical basis and guiding significance for the application of PVDF matrix composite fabric in the field of intelligent wearable electromagnetic shielding. |
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