Sergey I. Gutnikov

Influence of alumina on the properties of continuous basalt fibers

We study the influence of alumina percentage on fundamental properties (structure and crystallization) and applied properties (temperature range of manufacturing and strength) of basalt glasses and continuous basalt fibers (CBFs) on their base. Crystallization of high-alumina glasses and CBFs occurs in three steps. First, magnetite crystallizes, serving as nuclei for subsequent crystallization of augite mineral. Above 900°C, anorthite is the major crystallization product. For low-alumina fibers, augite is the major crystallization product. Fibers and glasses having high alumina percentages have the highest resistance to crystallization. IR spectroscopy showed that the structural connectivity of glasses and fibers increases with increasing alumina percentage. The breaking strength of fibers varies within 1.7–2.5 GPa, increasing with Al2O3 percentage.

Effect of ZrO2 on the alkali resistance and mechanical properties of basalt fibers

We have studied the effect of zirconia additions on the properties of basalt glasses and fibers. The solubility limit of ZrO2 in basalt glasses is determined to be 7.1 wt %. Fibers produced from modified basalt glass contain both tetragonal and monoclinic zirconia. The highest ZrO2 concentration in basalt fibers is 3.1 wt %. We have determined the fiber drawing temperature ranges and assessed the tensile strength and alkali resistance of the fibers. With increasing ZrO2 content, the tensile strength of the fibers (d = 11−12 μm) decreases from 1.8 to 0.6 GPa. The addition of less than 3.1 wt % ZrO2 increases the alkali resistance of the basalt fibers by 37%. The addition of more than 3.1 wt % ZrO2 to the glass batch reduces the alkali resistance and tensilestrength of the basalt fibers.

Effect of iron oxides on the fabrication and properties of continuous glass fibers

We have studied the effect of iron oxides (0–10 wt % in terms of FeO) on the fabrication conditions and properties of continuous Fe-containing glass fibers and have determined the temperature ranges of fiber fabrication. A relationship between the iron oxide content of glass and the fiber fabrication temperature has been established. Using differential scanning calorimetry and x-ray diffraction, we have investigated the effect of glass composition on the glass transition temperature and temperature range of crystallization of the fibers. At high iron oxide contents (5–10 wt %), the first to crystallize is magnetite, otherwise quartz appears first. Increasing the heat-treatment temperature leads to crystallization of pigeonite, augite, enstatite, anorthite, and labradorite.

Effect of silane/nano-silica on the mechanical properties of basalt fiber reinforced epoxy composites

Abstract The present study explains the role of surface modification of constituent materials on composite material performance. The influence of silane and nano-hybrid coatings on mechanical properties of basalt fibers and composite materials on their base was investigated. Infrared spectroscopy indicated that modification of basalt fiber surface and nano-SiO2 was successfully applied. The surface modification leads to the significant increase in the tensile strength of basalt fibers compared to the non-coated fibers. The tensile strength of silane-treated fibers was established 23% higher than the non-coated fibers, indicating that silane plays a critical role in the strength retention of basalt fibers. Also it was pointed out that silane coupling agents can be used for the preparation of the nano-hybrid coating. Addition of SiO2 nanoparticles into the fiber surface was incorporated to enhance the interfacial bonding of basalt fiber reinforced epoxy composite.

Thulium(III) trifluoroacetates Tm(CF3COO)3 · 3H2O and Tm2(CF3COO)6 · 2CF3COOH · 3H2O: Synthesis and crystal structure

Thulium trifluoroacetate compounds have been synthesized, Tm(CF3COO)3 · 3H2O (I) and Tm2(CF3COO)6 · 2CF3COOH · 3H2O (II). The structure of I has been refined by the Rietveld method on the basis of the structural data for Cd(CF3COO)3 · 3H2O. The structure of II has been solved in a single-crystal X-ray diffraction study. Compound I has been studied by thermal analysis. Crystals of I and II are monoclinic: for Ia = 9.062(2) Å, b = 18.678(3) Å, c = 9.687(2) Å, β = 113.93(1)°, Z = 2, space group P21/c, R1 = 0.062; for IIa = 8.560(4) Å, b = 19.866(5) Å, c = 20.813(7) Å, β = 101.69(4)°, Z = 8, space group C2/c, R1 = 0.0392. In the molecular structure of I, thulium atoms are bonded in pairs through four bridging trifluoroacetate anions to form dimers. The coordination polyhedron of the thulium atom also includes the three O atoms of the water molecules and the O atom of the monodentate trifluoroacetate group; the coordination number of the thulium atom is eight. In the chain structure of II, there are two crystallographically independent thulium atoms with coordination numbers 8 and 9. The coordination polyhedra of the Tm(1) and Tm(2) atoms are a distorted monocapped tetragonal antiprism and a distorted tetragonal antiprism, respectively. The Tm-O bond lengths are in the range 2.28(1)–2.85(2) Å. The thulium atoms are bound into chains through carboxylate groups. These chains are linked into layers through hydrogen bonds.

Bis(dimethylammonium) terephthalate

The asymmetric unit of the title compound, 2C2H8N+·C8H4O42−, comprises two crystallographically independent dimethylammonium cations and two half-terephthalate anions. The latter are each disposed about an inversion centre. N—H⋯O hydrogen bonds link the ions into a three-dimensional framework.