This research introduces an analysis of the anisotropic electrical resistivity (ER) and its relation to the electromagnetic shielding effectiveness (EMSE) for two injection-molded carbon-fiber-reinforced polybutylene terephthalates (PBTs). The properties were measured for 2-mm thick injection moldings considering the effect of melt temperature, injection velocity, and flow distance. The results for one compound showed an EMSE in the range of 30–40 dB, while EMSE for a compound with lower filler content is in the range of 45–75 dB. A combination of higher temperature and higher velocity leads to an increase of EMSE for both compounds in the range of 3%–8.5%. However, the increase in flow path reduced the EMSE for both compounds up to 10%. A novel experimental apparatus was used to measure the anisotropic ER in the three directions, that is, parallel, perpendicular, and transversal to flow. It is evident that injection molding induced high anisotropy for both compound specimens, and, depending on the processing conditions, produced similar longitudinal resistivity (0.2–4 Ω.cm) but higher transversal resistivity (8–22 Ω.cm). ER properties were compared with EMSE, evidencing an inverse relation as expected. Furthermore, it was found that the longitudinal resistivity is the main contributor to the specimens shielding.

中文翻译：

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加工条件对注塑聚对苯二甲酸丁二醇酯化合物电磁屏蔽和电阻率的影响

本研究介绍了对两种注射成型碳纤维增强聚对苯二甲酸丁二醇酯 (PBT) 的各向异性电阻率 (ER) 及其与电磁屏蔽效率 (EMSE) 的关系的分析。考虑到熔体温度、注射速度和流动距离的影响，对 2 毫米厚的注塑件进行了性能测量。一种化合物的结果显示 EMSE 范围为 30–40 dB，而填料含量较低的化合物的 EMSE 范围为 45–75 dB。较高温度和较高速度的结合导致两种化合物的 EMSE 在 3%–8.5% 范围内增加。然而，流路的增加使两种化合物的 EMSE 降低了 10%。一种新颖的实验装置用于测量三个方向的各向异性 ER，即，平行、垂直和横向流动。很明显，注塑成型对两种复合样品都产生了高各向异性，并且根据加工条件，产生了相似的纵向电阻率 (0.2-4 Ω.cm) 但横向电阻率更高 (8-22 Ω.cm)。ER 特性与 EMSE 进行了比较，证明了与预期的相反关系。此外，发现纵向电阻率是试样屏蔽的主要因素。