The paper presents a systematic review of recent advances in the development of polymer-matrix nanocomposites containing fibrous (sepiolite-palygorskite group) and non-swelling (kaolinite-serpentine group) clay minerals, as well as their modified forms obtained using surface reactions with organic and inorganic substances. An analysis of scientific trends and the current status of research in this area has been carried out, with particular emphasis on the influence of the types and forms of the considered mineral fillers on the properties of nanocomposites for various applications.
Keywords: polymer nanocomposites, clay minerals, kaolinite, halloysite, sepiolite, palygorskite
This work presents the results of investigation of one of the most widespread specimens of layered silicates minerals group - montmorillonite, that are the part of the natural dispersion of bentonite from Millerovo minefield via density functional theory (DFT) methods. The hygroscopic moistness of monoions forms of smectite group layered silicates is studied experimentally; these layered silicates are the most active components that significantly determine the properties of the dispersion as a whole. The correlation between hygroscopicity and theoretical values of inter-packet distances is established in studied samples by calculating total energies with optimization of the crystal structure.
Keywords: layered silicates, exchangeable cations, density functional theory, hygroscopicity, montmorillonite
This work deals with the study of atomic and electronic structure of kaolinite samples (Glukhovtsy deposit) and montmorillonite (Millerovsky deposit) by density functional theory. The applicability of existing exchange-correlation potential in the local density approximation (LDA) and the generalized gradient approximation (GGA) is analised for an adequate description of the physical properties of layered aluminosilicate. An experimental and theoretical study of the IR spectra of minerals, as well as the identification of the most intense absorption bands, performed in the approximation of DFT using the exchange-correlation potential PW91. The analysis of the band structure of these minerals, which showed that these compounds are direct-gap insulators.
Keywords: DFT, clay, clay minerals, phyllosilicates, atomic and electronic structure, crystalline systems, IR spectrum band strukutra, the electron density
This work deals with the integrated study of the composition and structural characteristics of the rock-forming minerals in Millerovsky bentonite clay. The qualitative and quantitative analysis of the clay samples is made by X-ray diffraction , X-ray photoelectron spectroscopy and thermal analysis . The morphological and microstructural features of minerals are investigated by scanning electron microscopy. The application of the method of direct theoretical calculation of the diffraction patterns is showm to determine the crystal-chemical parameters of the studied minerals. The results are aimed at explaining a number of physical and chemical properties of layered aluminosilicate.
Keywords: clays, clay minerals, layered silicates, x-ray diffraction, crystalline systems
The paper is devoted to developing an approach to solving the problem of structure identification of layered minerals of the kaolinite group by the Rietveld method. The calculations of the intensity of the diffracted X-ray radiation are performed for the koalinit samples obtained from different fields. Qualitative agreement between calculated and experimental results has managed the solution of the identification problem for the kaolinite unit cell Glukhovtsy deposit. The obtained results indicate the possibility of identifying the features of the crystal structure of layered minerals by direct calculation of diffraction patterns.
Keywords: layered minerals, crystal structure, group of koalinit, diffractogram, X-rays, Voigt function, phase composition