Recently, graphene and other graphene-based materials have become an essential part of composite science and technology. Their unique properties are not only restricted to graphene but also shared with derivative compounds like graphene oxide, reduced graphene oxide, functionalized graphene, and so forth. One of the most structurally important materials, graphene oxide (GO), is prepared by the oxidation of graphite. Though removal of the oxide groups can create vacancies and structural defects, reduced graphene oxide (rGO) is used in composites as effective filler similar to GO. Authors developed a new polyurethane nanocomposite using a derivative of grapheme, thermally reduced graphene oxide (rGO), to modify the matrix of polyurethane elastomers, by rGO.

We present a systematic investigation of the electronic properties of bulk and few layer ReS ₂ van der Waals crystals using low temperature optical spectroscopy. Weak photoluminescence emission is observed from two non-degenerate band edge excitonic transitions separated by ∼20 meV. The comparable emission intensity of both excitonic transitions is incompatible with a fully thermalized (Boltzmann) distribution of excitons, indicating the hot nature of the emission. While DFT calculations predict bilayer ReS ₂ to have a direct fundamental band gap, our optical data suggests that the fundamental gap is indirect in all cases.

Raman spectroscopy was used for studying strains in bulk GaN crystallized by HVPE on ammonothermally synthesized seeds. Two types of materials were examined in detail by Raman scattering before and after plastic deformation. Shifts of A ₁ (TO), E ₁ (TO), and E 2 high phonon lines were analyzed to determine strain and then stress tensors. Three areas were investigated in each sample: the seed, the crystal grown in the c-direction, and material laterally grown from the edges (wing). In this paper, differences in Raman spectra measured in these parts are shown and described in detail.

Polyurethane composites are materials of great interest nowadays due to their wide range of available forms and applications in industry. Controlling and achieving unique properties via matrix modifications and addition of various specific nanofillers seems be one of the key elements to success. The purpose of this work is to briefly present some examples of graphene nanoderivatives, their syntheses, properties and influence on polyurethane matrix after application. Structural, mechanical and electrical properties of graphene nanofillers were analyzed before and after implementation into polymer matrices. Additionally properties of obtained composites were considered in the context of shape memory. The first chapter presents methods of synthesizing carbon nanofillers and some structure investigations via x-ray Diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy. The second part discusses influence of graphene modifications on polymer structure and changes in thermomechanical properties via stress-strain tests and Thermogravimetry (TG).