Low Percolation Threshold and Enhanced Electromagnetic Interference Shielding in Polyoxymethylene/Carbon Nanotube Nanocomposites with Conductive Segregated Networks

Abstract

Aiming to construct a conductive polyoxymethylene (POM)/carbon nanotube (CNT) composite with low percolation threshold, polyethylene glycol/CNT­(PEGNT) masterbatch was first prepared and compounded with POM under temperature in the range of melting temperatures of PEG/POM (T m(PEG)–T m(POM)). When the PEG molecular weight was in the range of 6K–20K, the obtained PEGNT masterbatch was well coated on surface of POM particles, enriching a large number of PEGNT particles on their surfaces. In a subsequent process of short-time press molding, CNT was effectively controlled to be distributed at the interface between POM/PEG components, and massive two-phase interface transition regions formed to construct a conductive segregated structure (S-POM/PEGNT). With increasing PEG molecular weight and CNT content, the conductivity increased significantly. The low percolation threshold (φc) of 0.16 wt % was achieved for the S-POM/PEGNT composite, and a perfect three-dimensional conductive network of CNT formed in the matrix, leading to the appearance of a frequency-independent modulus “platform” in a rheological measurement. The composite exhibited relatively high electromagnetic interference shielding effectiveness, which was an absorption-based shielding mechanism.

Recent advances in structural design of conductive polymer composites for electromagnetic interference shielding

“…When the conductive nanofillers were increased to a specific value, the conductivity of the polymer suddenly increased sharply, which realized the transition from insulator to conductor 181 . For the CPCs with homogeneous structures, the construction of continuous networks required the mutual contraction of conductive nanofillers, resulting in a relatively high percolation threshold (often more than 30 wt%) 182,183 . However, the increase in nanofillers often resulted in severe deterioration of the processing and mechanical performance of CPCs.…”

Review of Polymer-Based Composites for Electromagnetic Shielding Application

“…Consequently, even at low filler content, the composite material exhibits strong electrical conductivity and EMI shielding capability [143][144][145]. Research by numerous investigators has demonstrated that the generation of a segregated structure is advantageous for reducing the percolation threshold of the composite, while synergistic filler interactions enhance the material's shielding ability and mechanical properties [39,40,[146][147][148][149]. The recent studies of segregated-structured electromagnetic shielding materials are summarized in Table 3.…”

“…[33][34][35]. To address these issues, researchers have focused on enhancing the structure of CPCs, including foam structures [36][37][38], separated structures [39,40], and layered structures [41][42][43]. These improved CPCs with enhanced structures exhibit superior electromagnetic shielding capabilities and have gained widespread application.…”

Recent Advancement in Solar‐Driven Interfacial Steam Generation for Desalination: A State‐of‐the‐Art Review

“…For example, 10 000 tonnes of oil must be used annually to yield freshwater of 1000 m 3 day À1 , significantly increasing greenhouse gas emissions. [9,10] Consequently, it is critical for the production of freshwater and wastewater treatment systems driven by sustainable and clean energy. [11,12] Earth's primary energy source is solar energy, which has rewards of being fresh and regenerative.…”