Electromagnetic Interference Shielding Effectiveness of Direct-Grown-Carbon Nanotubes/Carbon and Glass Fiber-Reinforced Epoxy Matrix Composites

Abstract

In this study, carbon nanotubes (CNTs) were grown under the same conditions as those of carbon fibers and glass fibers, and a comparative analysis was performed to confirm the potential of glass fibers with grown CNTs as electromagnetic interference (EMI) shielding materials. The CNTs were grown directly on the two fiber surfaces by a chemical vapor deposition process, with the aid of Ni particles loaded on them via a Ni-P plating process followed by heat treatment. The morphology and structural characteristics of the carbon and glass fibers with grown CNTs were analyzed using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and X-ray photoelectron spectrometry (XPS), and the EMI shielding efficiency (EMI SE) of the directly grown CNT/carbon and glass fiber-reinforced epoxy matrix composites was determined using a vector-network analyzer. As the plating time increased, a plating layer serving as a catalyst formed on the fiber surface, confirming the growth of numerous nanowire-shaped CNTs. The average EMI SE_T values of the carbon fiber-reinforced plastic (CFRP) and glass fiber-reinforced plastic (GFRP) with grown CNTs maximized at approximately 81 and 40 dB, respectively. Carbon fibers with grown CNTs exhibited a significantly higher EMI SE_T value than the glass fiber-based sample, but the latter showed a higher EMI SE_T increase rate. This indicates that low-cost, high-quality EMI-shielding materials can be developed through the growth of CNTs on the surface of glass fibers.

Keywords: carbon fiber; carbon nanotube; composites; electromagnetic shielding; glass fiber.

Figure 1

SEM images of the carbon fiber with CNTs grown on the surface; Ni-P-plated glass fiber; (a) NCF-10, (b) NCF-30, (c) NCF-60, (d) NCF-120, post-heat-treated glass fiber after Ni-P plating; (e) HNCF-10, (f) HNCF-30, (g) HNCF-60, (h) HNCF-120, glass fiber with CNTs grown on the surface after post-heat treatment; (i) HNCF-CNTs-10, (j) HNCF-CNTs-30, (k) HNCF-CNTs-60, (l) HNCF-CNTs-120.

Figure 2

SEM images of the glass fiber with CNTs grown on the surface; Ni-P-plated glass fiber; (a) NGF-10, (b) NGF-30, (c) NGF-60, (d) NGF-120, (e) HNGF-10, post-heat-treated glass fiber after Ni-P plating; (f) HNGF-30, (g) HNGF-60, (h) HNGF-120, glass fiber with CNTs grown on the surface after post-heat treatment; (i) HNGF-CNTs-10, (j) HNGF-CNTs-30, (k) HNGF-CNTs-60, (l) HNGF-CNTs-120.

Figure 3

SEM–EDS mapping images showing the distribution of carbon, nitrogen, oxygen, silicon, and nickel in the cross-section of the glass fiber: (a) HNGF-120 and (b) HNGF-CNTs-120.

Figure 4

XRD patterns of the (a) carbon fibers with grown CNTs and (b) glass fibers with grown CNTs as a function of plating time.

Figure 5

CNT growth mechanism: (a) tip-growth model and (b) base-growth model [49].

Figure 6

Survey-scan X-ray photoelectron spectra of the glass fibers modified by different treatments.

Figure 7

High-resolution XPS O_1s profiles of the (a) untreated glass fibers and (b) Ni-P plated glass fibers.

Figure 8

(a,b) Power coefficients of the CFRP and GFRP, respectively, with grown CNTs as a function of the plating time; (c,d) EMI SE_T of the CFRP and GFRP, respectively, with grown CNTs as a function of the plating time; (e,f) Contributions of SE_R and SE_A to the SE_T for CFRP and GFRP, respectively, with grown CNTs as a function of the plating time.

Figure 9

Schematic of the EMI shielding behavior of HNGF-CNTs/epoxy composites.