Carbon-Related Materials

Graphene is an archetype two-dimensional material with a remarkable band structure underlying its fascinating properties. Smart modifications of large-area graphene, i.e., by anchoring various chemical species expand the number of its potential applications depending on the specific functional groups or molecules attached to the graphene. Considering that only a sub-monolayer of functional groups is attached to the graphene surface, it is very challenging to prove their presence and to identify the nature of their mutual coupling, which spans from covalent to complex non-covalent interactions. In case of chemically modified mono- to few-layer graphene samples, direct detection of the functional groups is impossible. However, by applying advanced resonant Raman spectroscopy techniques, like surface-enhanced Raman scattering (SERS) one can directly observe Raman bands of the functional groups or molecules. In this chapter, we present the current state of the art for studying chemical functionalization of large-area graphene grown by chemical vapor deposition and discuss the significant potential and prospects of resonant Raman spectroscopies in understanding the coupling between the graphene and the anchored species.

This chapter presents a synthesis of special composite textile and graphite materials applications in the protection against electromagnetic non-ionizing radiation.

Several theoretical notions regarding the electromagnetic shielding mechanisms and the propagation of electromagnetic waves in conductive media are presented. Studies regarding the shielding properties of several types of graphite screens, by means of finite element method software are also presented. Highlighted are the effects of the screen’s width, the aperture size, and the incident wave polarization on the screen’s shielding effectiveness. Experimental results of the shielding properties of graphite screens also shown here, for screens which are made of graphite strips as well as for graphite impregnated textiles.

The current achievements of protective materials considering the technology used in communications and data transmission are described but also the prospective trends given the transition to 5G technology with promising perspectives in the field of communication using the terahertz domain.

The advances of carbon usage for Carbon Fibre Reinforce Polymer (CFRP) structures led to multiple applications in a large number of industries. This chapter presents methods for CFRP material characterization and usage for aeronautic, automotive and satellite applications. The major CFRP components used for antennas and microwave applications within these industries are presented. The accelerated adoption of carbon-based composites, current challenges and future directions are also reported.

Structural design and optimization of slotted waveguide antenna stiffened structures (SWASS) are considered. Radio frequency (RF) performance was considered by modeling waveguide slots for an antenna imbedded in an aircraft panel subject to external loading. An equivalent two-dimensional plate model was shown to be adequate for simplifying the waveguide core as an equivalent plate layer; however, smearing the stiffness effect of the slots was shown to be inaccurate. For higher fidelity, plate finite elements were used in a three-dimensional model with slots to evaluate the mechanical failure. This modeling technique proved cost-effective, employing few elements compared with three-dimensional solid modeling found in the literature. Validation with published experiments and verification with other published simulations demonstrated that it was sufficiently accurate for design purposes. Four SWASS configurations were compared. A slotted metallic foil waveguide tube wrapped with glass fiber and a carbon fiber inner mold line face sheet was the most effective concept, followed closely by all carbon fiber construction with slots cut through the outer mold line face sheet. Glass fiber face sheets for both inner and outer mold lines were the least effective concepts, whether or not the waveguide tubes were constructed of metallic foil or carbon fiber.

Azobenzene polymers have been the subject of intensive research due to their unique and unexpected properties that allow various applications. Many interesting properties of azopolymers are caused by or related with photoinduced trans–cis isomerization of azo chromophores, where the azo group undergoes a transition from the lower energy trans-form to less stable cis-form through the excited states. One of the most investigated properties of the azobenzene polymers is the capability to generate surface relief gratings (SRG). The effort to understand the SRG formation process remains unclear until now in defiance to many explorations. This chapter presents a study concerning the azopolymer response to the pulse laser irradiation, in the context of the SRG inscription.

Pulsed electrical discharges generated at atmospheric pressure in liquids have become one of the most interesting techniques for the functionalization of polymers. The generation of plasmas in liquids with short high voltage pulses for material modification is very new, but the approach offers the potential to be highly flexible with regard to their range of applications. When water is subjected to a high electric field, a high amount of excited species, such as hydrogen, oxygen, nitrogen, and hydroxyl radicals, are produced, which may efficiently interact with molecules and bulk-materials, inducing structural modifications. The material surface tailoring with different functionalities is possible, due to a wide range of functional groups that can be generated in liquid plasma by using anionic or cationic solutions. Polymer nanocomposites may be synthesized in a one-step process, nanomaterials being generated in plasma discharge and incorporated into the polymer matrix which is also placed in the plasma reactor during this process. Different reactions set in motion are determined by the way the electrical energy that is provided is dissipated in different mechanisms. Our experiments have shown that structural modifications of polymers and nanocomposite obtained when using nanosecond voltage pulses differ significantly from treatments with plasmas in liquids that have been generated with longer (microsecond) pulse duration. Therefore, pulse electrical discharges in liquids may be used for a controlled and efficient structural modification of polymers.

This chapter is a review on recent progress and new developments in modification of the polymer films structure and synthesis of nanocomposites after treatment by pulsed electrical discharges in liquids. First, a brief introduction of the plasma formed in liquids, the mechanism of plasma breakdown and reactive species formation. The polymers used in our studies and the influence of plasma treatment on the electrical, optical, and mechanical properties are described, according to the results obtained using different characterization methods.