Madinehei Milad, Kuester Scheyla, Kaydanova Tatiana, Moghimian Nima, David Éric
Mechanical Engineering Department, École de Technologie Supérieure, 1100 Notre-Dame St W, Montréal, QC H3C 1K3, Canada.
NanoXplore Inc., 4500 Boulevard Thimens, Saint-Laurent, QC H4R 2P2, Canada.
Polymers (Basel). 2021 Jul 31;13(15):2567. doi: 10.3390/polym13152567.
Polyester nanocomposites reinforced with graphene nanoplatelets (GnPs) with two different lateral sizes are prepared by high shear mixing, followed by compression molding. The effects of the size and concentration of GnP, as well as of the processing method, on the electrical conductivity and electromagnetic interference (EMI) shielding behavior of these nanocomposites are experimentally investigated. The in-plane electrical conductivity of the nanocomposites with larger-size GnPs is approximately one order of magnitude higher than the cross-plane volume conductivity. According to the SEM images, the compression-induced alignments of GnPs is found to be responsible for this anisotropic behavior. The orientation of the small size GnPs in the composite is not influenced by the compression process as strongly, and consequently, the electrical conductivity of these nanocomposites exhibits only a slight anisotropy. The maximum EMI shielding effectiveness (SE) of 27 dB (reduction of 99.8% of the incident radiation) is achieved at 25 wt.% of the smaller-size GnP loading. Experimental results show that the EMI shielding mechanism of these composites has a strong dependency on the lateral dimension of GnPs. The non-aligned smaller-size GnPs are leveraged to obtain a relatively high absorption coefficient (≈40%). This absorption coefficient is superior to the existing single-filler bulk polymer composite with a similar thickness.
通过高剪切混合，随后进行压缩模塑，制备了由两种不同横向尺寸的石墨烯纳米片（GnP）增强的聚酯纳米复合材料。实验研究了GnP的尺寸和浓度以及加工方法对这些纳米复合材料的电导率和电磁干扰（EMI）屏蔽行为的影响。具有较大尺寸GnP的纳米复合材料的面内电导率比跨平面体积电导率高约一个数量级。根据扫描电子显微镜图像，发现GnP的压缩诱导排列是这种各向异性行为的原因。复合材料中小尺寸GnP的取向受压缩过程的影响较小，因此，这些纳米复合材料的电导率仅表现出轻微的各向异性。在较小尺寸GnP负载量为25 wt.%时，实现了27 dB的最大电磁干扰屏蔽效能（SE）（入射辐射减少99.8%）。实验结果表明，这些复合材料的电磁干扰屏蔽机制强烈依赖于GnP的横向尺寸。利用未排列的较小尺寸GnP获得了相对较高的吸收系数（≈40%）。该吸收系数优于具有相似厚度的现有单填充本体聚合物复合材料。
