Roentgenographic studies are performed to investigate the structural changes in chitin under pressure and shear during its solid-state processing using a twin-screw extruder and Bridgman anvils. The...

The correlation between the molecular mass of a nascent ultrahigh-molecular-weight polyethylene reactor powder synthesized with a postmetallocene catalyst and the specific features of plastic deformation during the orientational drawing of the material compacted and consolidated under laboratory conditions is studied. In the range 5 × 10⁶−7 × 10⁶, molecular mass is controlled via a change in the polymerization conditions. Under comparable conditions of orientational drawing, the highest values of strength (2.65 GPa) and the elastic modulus (100 GPa) are found for samples with M = 6.3 × 10⁶.

The spatial structure of aggregates formed by detonation nanodiamonds is investigated using the wide-angle and small-angle X-ray scattering techniques. The effective sizes of crystallites and the crystallite size distribution function are determined. The shape of scattering aggregates is restored from the small-angle X-ray scattering data. An analysis of the results obtained allowed the conclusion that the nanodiamond aggregates have an extended spatial structure composed of nine to ten clusters, each involving four to five crystallites with a crystal lattice of the diamond type.

We report here the in situ polymerization of aniline in the presence of exfoliated graphite of two different grades (graphene and graphite) resulting in composite materials which are readily dispersible in N-methylpyrrolidone. Compared to polyaniline (PANI) prepared without graphene/graphite which becomes electrically non-conducting at pH > 3, the PANI–graphene/graphite composites showed significantly improved pH stability and electrochemical behaviour in aqueous electrolyte solutions at pH ≤ 8, without any further need of surface functionalization of the graphene/graphite flakes to stabilize the conducting form of polyaniline (PANI). The improved electroactivity is ascribed to the synergistic effect of graphene/graphite and PANI, and the network formation of the electrically conducting exfoliated graphites in the PANI matrix, which was electrochemically confirmed by simple cyclic voltammetric measurements at pH = 9.5 in the presence of the Ru(NH₃)₆ ^2+/3+ and Fe(CN)₆ ^3−/4− redox couples. Due to the dispersibility of the composites, thin films possessing stability in water can easily be prepared by solution casting for different types of solid-state chemical sensor and ion-selective electrode applications operating at neutral pH. By using sodium ascorbate as a model substance, we show that its amperometric detection at pH = 7.3 with the PANI–graphite films results in a current amplification of 1.3–10.2 times in the concentration range of 10⁻⁴–10⁻² M, compared to conventional PANI, which clearly demonstrates the advantage of incorporating exfoliated graphites in the PANI films. The materials reported in this paper were systematically characterized with cyclic voltammetry, FTIR, Raman and X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction and electrical conductivity measurements.