Electromagnetic Shielding and Flame Retardancy of Composite Films Constructed with Cellulose and Graphene Nanoplates

Abstract

Aimed at improving the electromagnetic (EM) shielding and flame retardancy of cellulose materials, graphene (GE) nanoplates were introduced into cellulose matrix films by blending in1-allyl-3-methylimidazolium chloride. The structure and performance of the obtained composite films were investigated using scanning electron microscopy, X-ray diffraction, thermogravimetric (TG) analysis, EM shielding effectiveness (SE), and combustion tests. GE introduction formed and stacked laminated structures in the films after drying due to controlled shrinkage of the cellulose matrix. The lamination of GE nanoplates into the films was beneficial for providing EM shielding due to multiple internal reflection of EM radiation; furthermore, they also increased flame resistance based on the “labyrinth effect.” The SE of these composite films increased gradually with increased GE content and reached 22.3 dB under an incident frequency of 1500 MHz. TG analysis indicated that these composite films possessed improved thermal stability due to GE addition. Reduced flammability was confirmed by their extended times to ignition or inability to be ignited, reduced heat release rates observed in cone calorimetry tests, and increased limiting oxygen index values. These films with improved EM shielding and flame retardancy could be considered potential candidates for multipurpose materials in various applications, such as electronics and radar evasion.

A comparative study of graphite and graphene sheets employed in polymer‐based electromagnetic shielding materials

“…The electrical conductivity of the films was assessed by conducting electrical resistance measurements as described in our previous research 22 . The complex EM parameters of the films were measured in the frequency range of 8.2–12.4 GHz (X‐band) using DR‐W0418 waveguide apparatus along with a vector network analyzer (DR series equipment used here and below, Beijing DR Technology Co., Ltd., Beijing, China) based on the ASTM D5568‐14 standard, where the relative complex permittivity and relative complex magnetic permeability were calculated from the S parameters by the test software.…”

Electrical, Thermo-Electrical, and Electromagnetic Behaviour of Epoxy Composites Reinforced with Graphene Nanoplatelets with Different Average Surface Area

“…This makes them candidates to improve the compatibility and effectiveness of electromagnetic shielding in the face of the growing boom of wireless communication devices (Wireless) and home devices [39] that emit within the same frequency range of the electromagnetic spectrum, producing noise, interference, and dynamic superposition of signals with a harmful effect on health [40]. The use of nanoreinforced polymers in the protection and attenuation of interference has precedents such as Printed Circuit Board shielding technology [41,42], electromagnetic shielding [43,44], and microwave absorption [45,46] applications. The absorption of electromagnetic waves in nanomaterials occurs by several mechanisms.…”