Conductive Composites Based on Polyurethane and Nanostructured Conductive Filler of Montmorillonite/Polypyrrole for Electromagnetic Shielding Applications

In this study, composites based on polyurethane (PU) derived from castor oil and montmorillonite/polypyrrole doped with dodecylbenzenesulfonic acid (MMt-PPy.DBSA) were developed. In order to investigate the potential use of these materials for electromagnetic shielding applications, the electrical and mechanical properties of PU/MMt-PPy.DBSA composites were determined and compared with composites containing neat PPy.DBSA. The electrical conductivity of PU/MMt-PPy.DBSA composites was found to be higher than those for PU/PPy.DBSA with a similar filler content. Additionally, with a higher conductive additive content, significant increases in the tensile stress (σ) and elastic modulus (E) were observed, suggesting that MMt-PPy.DBSA acts as reinforcing agent for the PU matrix. The electromagnetic interference shielding effectiveness (EMI SE) of composites is mainly dependent on the morphology and filler content. The PU/MMt-PPy.DBSA composite containing 25 wt % of MMt-PPy.DBSA showed a maximum EMI SE of -21 dB, which is similar to the value required for commercial applications (-20 dB). The results revealed that PU/MMt-PPy.DBSA composites are promising materials for electromagnetic shielding applications.

本研究开发了基于蓖麻油衍生聚氨酯（PU）以及十二烷基苯磺酸掺杂蒙脱土/聚吡咯（MMt-PPy.DBSA）的复合材料。为探究此类材料在电磁屏蔽领域的应用潜力，本研究测定了PU/MMt-PPy.DBSA复合材料的电学与力学性能，并与仅含纯PPy.DBSA的复合材料进行对比。结果表明，在填料含量相近的条件下，PU/MMt-PPy.DBSA复合材料的电导率高于PU/PPy.DBSA复合材料。此外，随着导电添加剂含量升高，材料的拉伸应力（σ）与弹性模量（E）均出现显著提升，提示MMt-PPy.DBSA可作为PU基体的补强剂。复合材料的电磁干扰屏蔽效能（EMI SE）主要取决于其微观形貌与填料含量。其中，含25 wt% MMt-PPy.DBSA的PU/MMt-PPy.DBSA复合材料的最大EMI SE可达-21 dB，与商业应用所需的-20 dB阈值相近。上述研究结果证实，PU/MMt-PPy.DBSA复合材料是一类极具应用前景的电磁屏蔽材料。