Pickering乳液技术制备纤维素纳米纤丝-还原氧化石墨烯/聚甲基丙烯酸甲酯电磁屏蔽复合材料

利用纤维素纳米纤丝（CNF）和氧化石墨烯（GO）共稳定的含有聚甲基丙烯酸甲酯（PMMA）的Pickering乳液法，并经抽滤、还原、热压等工艺制备高性能的纤维素纳米纤丝-还原氧化石墨烯/聚甲基丙烯酸甲酯（CNF-rGO/PMMA）电磁屏蔽复合材料。通过调节油相中聚合物的质量浓度、水油体积比，从而调控GO在复合材料中的质量分数。研究GO还原方式、质量分数及热压过程对所制备的CNF-rGO/PMMA电磁屏蔽复合材料的形貌结构与性能的影响。CNF-rGO/PMMA电磁屏蔽复合材料中GO经水合肼处理后有效还原为rGO，热压工艺使包裹在PMMA颗粒外的CNF-rGO片层与PMMA颗粒紧密堆积并形成交联的三维导电网络从而具有优异的导电率，在X波段不同频率（8.2~12.4 GHz）下具有良好的电磁屏蔽效能及稳定性，电磁屏蔽效能可达20 dB以上，可用于民用电磁屏蔽材料。 

Preparation of cellulose nanofiber-reduced graphene oxide/poly (methyl methacrylate) electromagnetic interference shielding composites by Pickering emulsion technology

Based on cellulose nanofiber (CNF) and graphene oxide (GO) co-stabilized Pickering emulsion with dichloroethane solution of poly (methyl methacrylate) (PMMA) as the oil phase, the cellulose nanofiber-reduced graphene oxide/poly (methyl methacrylate) (CNF-rGO/PMMA) electromagnetic interference (EMI) shielding composites were subsequently prepared by filtration, reduction and hot-pressing method. The mass fraction of GO in the EMI shielding composites was adjusted by the polymer concentration in the oil phase and the volume ratio of water to oil phase. The effects of GO reduction method, the mass fraction of GO and hot-pressing process on the morphology, structure and property of the obtained CNF-rGO/PMMA EMI shielding composite were studied. The reduction of hydrazine hydrate can transfer GO to rGO more effectively. The hot-pressing process facilitated CNF-rGO sheets surrounding PMMA micro-particles to closely be compacted with PMMA and meanwhile to form a 3D network structure of CNF-rGO sheets which endowed an excellent electrical conductivity of the obtained CNF-rGO/PMMA EMI shielding composites. The CNF-rGO/PMMA EMI shielding composites have good EMI shielding effectiveness and stability in the range of 8.2-12.4 GHz with over 20 dB of EMI shielding effectiveness and possess application in civil EMI material.