Low Percolation Threshold and Enhanced Electromagnetic Interference Shielding in Polyoxymethylene/Carbon Nanotube Nanocomposites with Conductive Segregated Networks
Chuanliang Chen, Xiaowen Zhao, Lin Ye
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 (Tm(PEG)–Tm(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.