One of the methods of obtaining reduced graphene oxide (rGO) involves the oxidation of graphite to graphene oxide, which is then exfoliated and reduced. Each of these stages has a decisive influence on the properties of the produced nanoadditive, which determines its subsequent application. The process conditions which are examined during the oxidation stage are related to: The mixing time of the reactants before oxidation, sonication of the reaction mixture, and its composition. During reduction optimization, in turn, the form of the GO sample and the method of its purification, as well as the temperature at which this process took place, are examined. At each stage, the determined structural parameters of the produced materials (GO and rGO) are related to their morphology (SEM—scanning electron microscope), oxidation state (FTIR—Fourier transform infrared spectroscopy, EDS—energy-dispersive spectrometer), structure defect (Raman spectroscopy), as well as the number of layers and crystalline structure (WAXS—wide-angle X-ray scattering). The obtained results show that the shorter mixing time of the reactants determines the formation of more oxygen functional groups. On the basis of the obtained results, the process conditions that enable the production of multilayer, well-exfoliated reduced graphene oxide, with only a slightly defected structure, are established.

The alternative method of reducing the flammability of polyethylene terephthalate (PET) fibers, analogous to dyeing of PET fibers with dispersed dyes in a high-temperature bath, was proposed. A commercial organophilic montmorillonite Cloisite^®15A (C15A) was applied as a flame retardant. The aim of the presented work was to evaluate the effectiveness of the introduced modifier and the improvement of the flame-retardant properties of PET fibers by limiting oxygen index (LOI) and thermogravimetric analysis (TGA) measurements. Evolved gas analysis (EGA) by spectrometric method (FTIR) during coupled thermogravimetric analysis (TGA) was applied in order to confirm no increase in the toxicity of volatile degradation products released from burning modified fibers. The nanocomposite nature of modified fibers was confirmed based on the structural parameters of the fibers determined using wide-angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) X-ray diffraction methods.

This paper refers to the formation and properties of polypropylene/stearic acid (PP/SA) composite fibers. For the investigation, commercial metallocene-catalyzed PP polymer and SA were used. The fibers were produced in laboratory conditions using the single screw spin draw device. The textile-mechanical properties, surface composition, morphology and supermolecular structure of as-spun fibers were studied. Moreover, the nonisothermal crystallization of the PP/SA blend and melting behavior of fibers were analyzed. In the investigation Fourier transform infrared–attenuated total reflectance, scanning electron microscopy, differential scanning calorimetry and wide-angle X-ray analytical methods were used. The research showed that the PP/SA blend has lower viscosity compared to the pure polymer and that during the PP crystallization phase, separation is induced. SA delays crystallization of PP, and interaction between SA and PP is observed. The as-spun PP/SA fibers have higher linear density, higher elongation at break and slightly lower tenacity compared to fibers produced from pure PP. The fibers contain a structure with high content of mesophase. During fiber formation, SA migrates towards the fiber surface and forms droplets located beneath the surface of the fiber or crystallizes outside in the form of flake-like crystals.

In this study, flame-retardant poly(ethylene terephthalate) (PET) fibres were produced using a high-temperature bath method similar to dyeing fibres with disperse dyes. A mixture of aqueous solutions of silicon and phosphorus compounds was used as the flame retardant. Samples of the modified fibres were examined by thermogravimetric analysis. The residue left after limited oxygen index test was analysed by scanning electron microscopy. Effect of the flame retardant on changing the supermolecular structure of PET fibres was evaluated using wide-angle X-ray diffraction. Mechanical properties of the modified PET fibres as compared with standard fibres were also examined.