Coupled effect of self-assembled nucleating agent, Ni-CNTs and pressure-driven flow on the electrical, electromagnetic interference shielding and thermal conductive properties of poly (lactic acid) composite foams. (10th November 2022)

• Record Type: Journal Article
• Authors: Kuang, Tairong; Ju, Jiajun; Chen, Feng; Liu, Xianhu; Zhang, Shuidong; Liu, Tong; Peng, Xiangfang
• Is Part Of: Composites science and technology. Volume 230(2022)Part 1
• Publication Date: 2022-11-10
• Subjects: Multifunctional composites -- Electrical properties -- Electromagnetic interference shielding (EMI) -- Strength -- Scanning electron microscopy (SEM); Composite materials -- Periodicals; Composite materials; Fibrous composites; Periodicals; 620.118
• DOI: 10.1016/j.compscitech.2022.109736
• Languages: English
• ISSNs: 0266-3538

Abstract

Abstract: Biobased and biodegradable poly (lactic acid) (PLA) composite foams with good mechanical properties, a low percolation threshold, and absorption-dominant shielding properties with little reflection are considered suitable substitutes for traditional petroleum-based polymer composite foams in various applications. However, fabricating PLA composite foams that simultaneously satisfy all the above properties remains a significant challenge, particularly at low conductive filler addition. In this study, we successfully fabricated high-performance multifunctional PLA/self-assembled nucleating agent (TMC-306)@Ni-CNTs composite foams. In the ternary composites system, PLA and 0.5 wt% TMC-306 were melt mixed first to prepare granules and used as a polymer matrix, while Ni-CNTs were employed as a conductive segregated filler. To determine the coupled effect of TMC-306, Ni-CNTs, and pressure-driven flow on PLA composite foams, rheological, crystallization, and morphological properties of ternary composites were initially investigated. The results demonstrated that the increased complex viscosity of composites with increasing Ni-CNTs content affected the flow orientation under pressure-driven flow and the pore growth of the subsequent foaming process. The low content of Ni-CNTs could play a synergistic role with TMC-306 to improve PLA crystallization ability, whereas the nucleating agent effect was inhibited at high Ni-CNTs content. Additionally, pressure-driven flow induced the formation of segregated oriented conductive networks and ordered crystalline structures in the matrix, which significantly impacted on the low-temperature foaming performance of PLA composites. After supercritical carbon dioxide (Sc-CO2 ) foaming treatment, the composite foams exhibited an ultralow percolation threshold of 0.076 vol% and high electrical conductivity of 7.58 × 10 −2 S/cm at an ultralow Ni-CNTs content of 0.805 vol%. Moreover, the composite foams containing 0.805 vol% Ni-CNTs achieved a high electromagnetic interference (EMI) shielding effectiveness (SE) of 25.2 dB and an absorption-dominant shielding mechanism with a high absorptivity of 86%. It also had a low density of 0.36 g/cm 3, a high compressive strength of 5.42 MPa and a good thermal conductivity of 62.3 mW·m −1 ·K −1 . In summary, this study may provide a facile and cost-effective strategy for developing high-performance PLA composite foams with broad applications. Graphical abstract: Image 1