Enhancement of Electromagnetic Interference Shielding Performance and Wear Resistance of the UHMWPE/PP Blend by Constructing a Segregated Hybrid Conductive Carbon Black-Polymer Network

Superior mechanical, electrical, dielectric, and EMI shielding properties of ethylene propylene diene monomer (EPDM) based carbon black composites

In this study, the mechanical, electrical, dielectric, and electromagnetic interference (EMI) shielding properties of ethylene propylene diene monomer (EPDM) based carbon black composites, namely high abrasion furnace (HAF) and conductive Printex blacks, were investigated and their effectiveness compared. The results show that Printex black filled composites exhibited superior properties in all aspects compared to HAF filled composites. The electrical percolation threshold value of Printex black filled composites was approximately 1/2 to 1/3 lower compared to HAF black filled composites based on classical theory and the Sigmoidal model. Moreover, the tensile modulus, dielectric permittivity, and EMI shielding efficiency (SE) of the Printex black filled composites were 4.6 times, in the order of 106 at 1 kHz, and 6.65 times improved compared to HAF black filled composites at their 40 phr loadings, respectively. The Printex black filled 40 phr loaded composite showed an EMI SE of 49.94 dB that is 99.999% the attenuation of EM radiation. These properties can be attributed to the high structure of Printex black, which facilitates the ease of formation of the conductive channel through the polymer matrix, higher reinforcement, higher interfacial polarization, and high absorption of radiation. These properties were compared with some published literature on carbon black filled composites and it was found that the results of the Printex black filled composites are highly competitive with the published work. The results show that these composites are highly effective for load bearing materials, supercapacitors, and EM radiation protection.

Flexible Polydimethylsiloxane Composite with Multi-Scale Conductive Network for Ultra-Strong Electromagnetic Interference Protection

Highlights

A multi-scale conductive network was constructed in flexible PDMS/Ag@PLASF/CNT composite with micro-size Ag@PLASF and nano-size CNT. The PDMS/Ag@PLASF/CNT composite showed outstanding electrical conductivity of 440 S m-1 and superior electromagnetic interference shielding effectiveness of up to 113 dB. The PDMS/Ag@PLASF/CNT composites owned good retention (> 90%) of electromagnetic interference shielding performance even after subjected to a simulated aging strategy or 10,000 bending-releasing cycles.

Abstract

Highly conductive polymer composites (CPCs) with excellent mechanical flexibility are ideal materials for designing excellent electromagnetic interference (EMI) shielding materials, which can be used for the electromagnetic interference protection of flexible electronic devices. It is extremely urgent to fabricate ultra-strong EMI shielding CPCs with efficient conductive networks. In this paper, a novel silver-plated polylactide short fiber (Ag@PLASF, AAF) was fabricated and was integrated with carbon nanotubes (CNT) to construct a multi-scale conductive network in polydimethylsiloxane (PDMS) matrix. The multi-scale conductive network endowed the flexible PDMS/AAF/CNT composite with excellent electrical conductivity of 440 S m−1 and ultra-strong EMI shielding effectiveness (EMI SE) of up to 113 dB, containing only 5.0 vol% of AAF and 3.0 vol% of CNT (11.1wt% conductive filler content). Due to its excellent flexibility, the composite still showed 94% and 90% retention rates of EMI SE even after subjected to a simulated aging strategy (60 °C for 7 days) and 10,000 bending-releasing cycles. This strategy provides an important guidance for designing excellent EMI shielding materials to protect the workspace, environment and sensitive circuits against radiation for flexible electronic devices.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40820-022-00990-7.

Bio-Based Eucommia ulmoides Gum Composites with High Electromagnetic Interference Shielding Performance

Herein, high-performance electromagnetic interference (EMI) shielding bio-based composites were prepared by using EUG (Eucommia ulmoides gum) with a crystalline structure as the matrix and carbon nanotube (CNT)/graphene nanoplatelet (GNP) hybrids as the conductive fillers. The morphology of the CNT/GNP hybrids in the CNT/GNP/EUG composites showed the uniform distribution of CNTs and GNPs in EUG, forming a denser filler network, which afforded improved conductivity and EMI shielding effect compared with pure EUG. Accordingly, EMI shielding effectiveness values of the CNT/GNP/EUG composites reached 42 dB in the X-band frequency range, meeting the EMI shielding requirements for commercial products. Electromagnetic waves were mainly absorbed via conduction losses, multiple reflections from interfaces and interfacial dipole relaxation losses. Moreover, the CNT/GNP/EUG composites exhibited attractive mechanical properties and high thermal stability. The combination of excellent EMI shielding performance and attractive mechanical properties render the as-prepared CNT/GNP/EUG composites attractive candidates for various applications.

Endowing Acceptable Mechanical Properties of Segregated Conductive Polymer Composites with Enhanced Filler-Matrix Interfacial Interactions by Incorporating High Specific Surface Area Nanosized Carbon Black

Tuning the high properties of segregated conductive polymer materials (CPCs) by incorporating nanoscale carbon fillers has drawn increasing attention in the industry and academy fields, although weak interfacial interaction of matrix-filler is a daunting challenge for high-loading CPCs. Herein, we present a facile and efficient strategy for preparing the segregated conducting ultra-high molecular weight polyethylene (UHMWPE)-based composites with acceptable mechanical properties. The interfacial interactions, mechanical properties, electrical properties and electromagnetic interference (EMI) shielding effectiveness (SE) of the UHMWPE/conducting carbon black (CCB) composites were investigated. The morphological and Raman mapping results showed that UHMWPE/high specific surface area CCB (h-CCB) composites demonstrate an obviously interfacial transition layer and strongly interfacial adhesion, as compared to UHMWPE/low specific surface area CCB (l-CCB) composites. Consequently, the high-loading UHMWPE/h-CCB composite (beyond 10 wt% CCB dosage) exhibits higher strength and elongation at break than the UHMWPE/l-CCB composite. Moreover, due to the formation of a densely stacked h-CCB network under the enhanced filler-matrix interfacial interactions, UHMWPE/h-CCB composite possesses a higher EMI SE than those of UHMWPE/l-CCB composites. The electrical conductivity and EMI SE value of the UHMWPE/h-CCB composite increase sharply with the increasing content of h-CCB. The EMI SE of UHMWPE/h-CCB composite with 10 wt% h-CCB is 22.3 dB at X-band, as four times that of the UHMWPE/l-CCB composite with same l-CCB dosage (5.6 dB). This work will help to manufacture a low-cost and high-performance EMI shielding material for modern electronic systems.