Sidi Salah Lakhdar, Ouslimani Nassira, Danlée Yann, Huynen Isabelle
Research Unit Materials, Processes and Environment (URMPE), Faculty of Technology, Université M'Hamed Bougara Boumerdès, Boumerdes 35000, Algeria.
Processing and Shaping of Fibrous Polymers Laboratory, Faculty of Technology, Université M'Hamed Bougara Boumerdès, Avenue of Independence, Boumerdes 35000, Algeria.
Micromachines (Basel). 2022 Dec 5;13(12):2152. doi: 10.3390/mi13122152.
The present paper aims to address the crucial concern of pollution induced by growing plastic waste and electromagnetic interference (EMI). Nanocomposites combining poly(lactic acid) (PLA) and organo-modified montmorillonite (OMMT) are synthesized and compression molded into thin films. A first set of samples, referred as virgin, was kept as is, while a second set of samples were photochemically, thermally and hydrolytically aged before mechanical recycling via extruding and second compression molding, resulting in the so-called recycled composite. The electromagnetic (EM) properties with a focus on microwave absorption performances of virgin and recycled samples are compared for various thicknesses and weight concentrations of OMMT in PLA matrix. The EM performances are gauges by Rozanov and Salisbury structures that consist in one- and two-layer stacks of composite films back-coated by a metal foil. Characterization in Rozanov configuration shows an average absorption index over the Ka band of 29.3% and 21.1% for, respectively, virgin and recycled PLA reinforced with 4 wt.% OMMT. An optimization of the film thickness is proposed; up to 61.85% and 80% of absorption with a thickness of 1.4 mm and 3.75 mm, respectively, is reached with a metal back-coated rPLA-4%OMMT film. Characterization in Salisbury configuration gives advantage to the recycled structure with an average absorption of 49.6% for a total thickness of 1.4 mm. The requirements of EMI shielding are met by PLA-OMMT composites with a certain benefit of recycling process on EM performance.
本文旨在解决日益增长的塑料垃圾和电磁干扰（EMI）所引发的污染这一关键问题。将聚乳酸（PLA）与有机改性蒙脱土（OMMT）相结合的纳米复合材料被合成，并通过压缩模塑制成薄膜。第一组样品，即原始样品，保持原样，而第二组样品在通过挤出和二次压缩模塑进行机械回收之前，先进行光化学、热和水解老化处理，从而得到所谓的再生复合材料。针对PLA基体中不同厚度和重量浓度的OMMT，比较了原始样品和再生样品的电磁（EM）特性，重点关注微波吸收性能。通过Rozanov结构和Salisbury结构来测量EM性能，这两种结构分别由复合薄膜的单层和双层堆叠组成，并在背面涂覆金属箔。Rozanov配置的表征显示，对于分别用4 wt.% OMMT增强的原始PLA和再生PLA，在Ka波段的平均吸收指数分别为29.3%和21.1%。提出了薄膜厚度的优化方案；对于背面涂覆金属的rPLA - 4%OMMT薄膜，厚度分别为1.4 mm和3.75 mm时，吸收分别达到61.85%和80%。Salisbury配置的表征表明，再生结构具有优势，总厚度为1.4 mm时平均吸收为49.6%。PLA - OMMT复合材料满足了EMI屏蔽的要求，并且回收过程对EM性能有一定益处。
