Selective Microwave Sintering to Prepare Multifunctional Poly(ether imide) Bead Foams Based on Segregated Carbon Nanotube Conductive Network

Abstract

Carbon nanotube/poly­(ether imide) (CNT/PEI) bead foam parts featuring a lightweight and segregated conductive network were prepared by a judicious combination of selective microwave (MW) sintering and carbon dioxide/tetrahydrofuran (CO2/THF) co-foaming. This way endowed the CNT/PEI conductive foam with adjustable cellular structure and tunable performance by simply changing the CNT content and MW processing condition. Owing to its unique structure, the CNT/PEI conductive foam (0.28 g/cm3) with a CNT content of 0.90 vol % presented a good electrical conductivity (20.7 S/m) and electromagnetic interference (EMI) shielding performance (30.3 dB). In addition, the CNT/PEI conductive foam exhibited an ultralow percolation threshold (0.029 vol %) and presented superior piezoresistive performance under an applied pressure of 0–3.5 MPa and strain of 0–10%, due to the “condensation–recovery” transition mechanism of the integral CNT network of the conductive foam. This study provided an innovative approach to fabricate high-performance polymer bead foam parts with multifunctionality.

Preparation of Highly Efficient Electromagnetic Interference Shielding Polylactic Acid/Graphene Nanocomposites for Fused Deposition Modeling Three-Dimensional Printing

“…42 In addition, in the classical electromagnetic theory, the skin depth δ, which represents the depth where the intensity of the electromagnetic waves inside the material decreases to 1/e, was also used to reveal the shielding mechanism. The related equations are expressed as follows: 19,38,43 d e SE 20 lg…”

Fabricating bimodal microcellular structure in polystyrene/carbon nanotube/glass‐fiber hybrid nanocomposite foam by microwave‐assisted heating: A proof‐of‐concept study

“…Hence, microwave heating has been extensively proposed in recent years as a green heating resource to be used in different areas, especially in polymers. For instance, the microwave heating method has been employed for processing or synthesizing polymers in many fields such as rubber vulcanization, 2 polymerization, 3 fabrication of multifunctional composites, 4,5 modification of carbonaceous particles, 6 shape‐memory materials, 7,8 preparation of thermoset, 9 and bead foams 10 . Since most polymers are to some extend transparent to microwave radiation, the dispersion of appropriate additives as microwave absorbers in the polymer matrix is necessary.…”

“…For instance, the microwave heating method has been employed for processing or synthesizing polymers in many fields such as rubber vulcanization, 2 polymerization, 3 fabrication of multifunctional composites, 4,5 modification of carbonaceous particles, 6 shape-memory materials, 7,8 preparation of thermoset, 9 and bead foams. 10 Since most polymers are to some extend transparent to microwave radiation, the dispersion of appropriate additives as microwave absorbers in the polymer matrix is necessary. There Mehrnaz Shahbazi, Mohammad Aghvami-Panah, Mahyar Panahi-Sarmad, and Amir Abbas Seraji contributed equally to this study.…”

Microwave‐Assisted Confining Flame‐Retardant Polypropylene in Carbon Nanotube Conductive Networks for Improved Electromagnetic Interference Shielding and Flame Retardation

“…Over the last decades, considerable research has been put forth to combine polymer matrix and conductive fillers to achieve conductive polymer composites (CPCs) with improved electrical conductivity. [ 1–9 ] These CPCs have been widely applied in many advanced fields such as antistatic, [ 10 ] electrical heating, [ 11,12 ] electromagnetic interference (EMI) shielding, [ 13,14 ] and smart sensors. [ 15,16 ] In general, a high loading of conductive fillers is required to achieve the desirable electrical conductivity for conventional CPCs, and the accompanying high cost, poor processability, low ductility, and in particular the ease‐of‐burning property limit their practical applications.…”