4.7 Article

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

Journal

COMPOSITES SCIENCE AND TECHNOLOGY
Volume 230, Issue -, Pages -

Publisher

ELSEVIER SCI LTD
DOI: 10.1016/j.compscitech.2022.109736

Keywords

Multifunctional composites; Electrical properties; Electromagnetic interference shielding (EMI); Strength; Scanning electron microscopy (SEM)

Funding

  1. Natural Science Foundation of Zhejiang Province [LZ21E030002]
  2. National Natural Science Foundation of China [52173046, 51803062]
  3. Natural Science Foundation of Guangdong Province [2019A1515012125]
  4. Fundamental Research Funds for the Provincial Universities of Zhejiang [A2020008]

Ask authors/readers for more resources

In this study, high-performance PLA/self-assembled nucleating agent@Ni-CNTs composite foams were successfully fabricated. These foams exhibited an ultralow percolation threshold and high electrical conductivity under pressure-driven flow. After supercritical carbon dioxide foaming treatment, the composite foams also showed high electromagnetic interference shielding effectiveness and an absorption-dominant shielding mechanism, with low density, high compressive strength, and good thermal conductivity.
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 multi-functional 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 x 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.

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