Electromagnetic Shielding Effectiveness of Thin Film with Composite Carbon Nanotubes and Stainless Steel Fibers

Abstract

Using the polymer blending method, conductive materials and waterborne polyurethane (WPU) were mixed to fabricate conductive composite films for application in electromagnetic shielding. First, nitric acid was used to purify the multi-walled carbon nanotubes (MWCNT). Second, sodium dodecyl sulfate (SDS) was utilized to disperse the carbon nanotubes, and then they were mixed with 8 microm diameter and 2 mm long stainless steel fibers (SSF) in the WPU by the polymer blending method. Finally, the thickness of 0.25 mm of conductive composite film was fabricated by means of coating. According to the ASTM D4935-99 standard, a coaxial transmission line was used to measure the electromagnetic shielding effectiveness (EMSE) of conductive composite film within the range of 50 MHz approximately 3.0 GHz. Moreover, the influence of the prior and posterior dispersion of carbon nanotubes dispersed on electromagnetic shielding was dealt with in the paper. Results demonstrated that the conductive composite film, within 50 MHz approximately 3.0 GHz, fabricated by the 15 wt% of the multi-walled carbon nanotubes and 30 wt% of the stainless steel fibers can achieve the maximum of the electromagnetic shielding effectiveness, 34.86 dB, and its shielding effect, 99.9%.

Effect of gas counter pressure on the carbon fiber orientation and the associated electrical conductivities in injection molded polymer composites

“…Conductive polymer composites are obtained by blending conductive additives such as carbon fiber [1,2], carbon black [3,4], stainless steel fibers [5,6] and carbon nanofibers and nanotubes [7,8] with a polymer matrix. Electrically conductive polymer composites are promising materials for many engineering applications, such as rechargeable batteries, electromagnetic interference shielding, electrostatic dissipation, sensors and electronic devices.…”

“…Furthermore, during the molding process, the carbon fiber will become highly oriented along the flow field, leading to a reduction in conductivity and severe warpage due to non-uniform shrinkage. As previously described [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], the composite properties are determined by fiber characteristics such as shape and aspect ratio, as well as their orientation, distribution and volume fraction in the polymer matrix. From the viewpoint of the part manufacturer, it is desirable to reduce the fiber content while maintaining the high conductivity in the composites.…”

Foam injection molding of polypropylene/stainless steel fiber composites for efficient EMI shielding

“…Conductive polymer composites (CPCs) are becoming promising candidates to be employed as EMI shields as they offer light weight, low cost, good processability, and high resistance to corrosion and various CPCs containing micro-sized [4][5][6][7][8][9], and nano-sized [10][11][12][13][14][15] fillers have been developed for EMI shielding applications. However, CPCs are not yet very successful in replacing metal-based shields due to the required high filler loading.…”

Thermal behavior and mechanical properties of nanocomposites of polycarbonate reinforced with multiwalled carbon nanotubes

“…Although several methods are available to impart electrical conductivity to polymers, the simplest and easiest way is to directly incorporate conductive fillers into the polymer matrices by melt mixing using different preparation methods such as extrusion molding and injection molding. As the conductive fillers, carbon fiber, carbon nanotubes (CNTs), carbon black, graphene sheet, stainless steel fibers, and metallic nanowires can be used . Since the discovery of CNTs by Iijima in 1991 , they have generally been regarded as fillers with high potential to improve the mechanical properties and electrical conductivity of polymers, owing to their unique nanostructure, excellent mechanical, thermodynamicand conductive properties, and high‐aspect‐ratio features .…”