Reinforcement of Electromagnetic Wave Absorption Characteristics in PVDF-PMMA Nanocomposite by Intercalation of Carbon Nanofibers

Abstract

With the recent developments in the millimeter and sub-millimeter wave instruments and devices, there is a need to develop electromagnetic (EM) wave absorbing materials in these frequency bands for applications like electromagnetic interference control, electromagnetic compatibility, etc. In this work, carbon nanofibers (CNF) were uniformly dispersed in a blend of poly(methyl methacrylate), polyvinylidene fluoride and cyanoacrylate for air spray coating a film on the cellulosic substrates. The samples were characterized for evaluation of their structure, morphology, electrical and EM absorption properties in 0.15–1.2 THz range by X-ray diffraction, field emission electron microscopy, I–V measurements and terahertz time domain spectroscopy. These coatings can conveniently be applied to the material surfaces by conventional air spray painting method, which makes this technique cost-effective as well as easy to deploy in various applications. The electrical conductivity enhancement in the samples has been attributed to the formation of conducting network by uniform distribution of CNFs in the insulating polymer matrix. As a result, the shielding effectiveness (SE) has been observed to improve with the increase in CNF’s loading in the polymer matrix. The SE is also a function of frequency, which is attributed to the increase in the skin depth. A SE of 20 dB has been estimated in these samples for the frequencies 1 THz and higher, which is of significant importance for the use of this technique in practical applications.