V. N. Strel’nikov

New high-density environmentally clean polyurethane materials with binary plasticizers

Thermal and physicomechanical properties of thermoplastic polyurethane binders plasticized with mixtures of low-melting diurethanes with low-molecular-weight liquids were studied. Regular trends in the effect of components of mixed plasticizers on the properties of polyurethane thermoplastics filled with finely dispersed tungsten were revealed.

Chemical structure of fibers of ultra-high-molecular-weight polyethylene upon ion-beam treatment and post-irradiation grafting of acrylic monomers

Surface modification of fibers fabricated from ultra-high-molecular-weight polyethylene by pulsed ion-beam treatment was studied. The structure and morphology of the surface layer were examined by the IR MFTIR method and X-ray diffraction analysis. A post-irradiation grafting of a number of acrylic monomers to the fiber surface was performed.

Behavior in a humid medium of segmented polyurethane-ureas with dissimilar thermodynamically compatible and incompatible flexible blocks

Fundamental aspects of how moisture sorption affects physicomechanical properties of polyurethaneureas based on mixtures of oligoether and oligodiene diisocyanates were studied. Advantages of elastomers with dissimilar flexible blocks in providing an enhanced strength of the material in a humid atmosphere and in contact with water were revealed.

Synthetic pitches based on the anthracene fraction of coal tar

The work reports results of investigations on the properties of pitches produced from the anthracene fraction of coal tar by means of the air-blowing and thermal cracking methods. For comparison, samples of coal tar pitch and air-blown pitches were used. The following parameters were determined: softening point, content of volatile matter, fractional and elemental compositions. In addition, thermal analysis and infra-red spectroscopy were performed. For cokes produced from the given pitches, the microstructure, porous structure and reactivity were analyzed. It was ascertained that pitches with cross-linked molecular structures formed during air-blowing of the anthracene fraction. These structures are characterized by low thermal stability—a feature that determines reduced coke residues of pitches and their elevated softening points, as well as the impossibility of forming the mesophase during coking, even for low viscosity and low contents of quinoline insolubles and toluene insolubles. Cokes produced from the air-blown anthracene fraction have a porous structure with high specific surface area. A porous structure and quinoline insolubles of the initial pitches lead to enhanced reactivity of producible cokes. During thermal cracking, i.e., under high temperatures and pressures, high-molecular condensed aromatic compounds are formed. These compounds determine the increased carbon content in pitches, the thermal stability of cokes, and the possibility of largesized mesophases forming, thus contributing to the formation of needle cokes. The thermal cracking process conditions the partial reactions of hydrocracking of heterocyclic compounds in the anthracene fraction; this leads to reduced contents of heteroatoms in producible pitches. While selecting pitches to obtain either isotropic or needle cokes, one should not be guided only by the softening point and contents of quinoline insolubles and toluene insolubles. A set of investigation methods and knowledge of the processing techniques and the nature of the initial raw materials are apparent prereqisites.

Agglomeration of the condensed phase of energetic condensed systems containing modified aluminum

Thermodynamic analysis of aluminum-containing energetic condensed systems was performed. It was shown that the replacement of aluminum by aluminum carbide led to a decrease in the amount of the condensed phase in the combustion products and a reduction in the specific impulse. The particle size distribution of the condensed phase of samples of energetic condensed systems containing different amounts of aluminum particles coated with aluminum carbide was studied experimentally. It was found that replacing aluminum with a particle size of 18–20 µm nanosized aluminum halved the maximum size of condensed-phase agglomerates of the combustion products.

Curing of epoxy-anhydride formulations in the presence of imidazoles

Differential scanning calorimetry was used to study the reaction of isomethyltetrahydrophthalic anhydride with phenyl glycidyl ether and the curing kinetics of diglycidyl ether of diphenylolpropane in the presence of imidazoles. The deformation-strength characteristics of cured epoxy polymers were determined.

Influence of the composition of acrylamide–acrylonitrile–2-acrylamido-2-methylpropanesulfonic acid terpolymer on its resistance to high temperatures and salts

The influence of the ratio of the acrylamide, acrylonitrile, and 2-acrylamido-2-methylpropanesulfonic acid monomeric units in the terpolymer on its resistance to elevated temperatures and sensitivity to calcium salts was studied. The influence of the terpolymer composition on the chemical transformations occurring under the conditions of thermal and hydrothermal treatment was studied by TGA and IR spectroscopy. The degree of hydrolysis of the terpolymers influences their resistance to CaCl2. The resistance of the terpolymers to CaCl2 additions at their concentrations of up to 7 wt % is preserved at the content of 2-acrylamido-2-methylpropanesulfonic acid units higher than 20 mol %. The revealed features allow optimization of the structure of polymer systems used in drilling lubricants.

Structure and properties of segmented polyurethane-ureas with dissimilar soft blocks

Structure and properties of segmented polyurethane-ureas with mixed nonpolar and polar soft segments were studied. Advantages of elastomers based on mixtures of oligobutadiene and oligoether diisocyanates in providing high strength properties combined with frost resistance are demonstrated.

Preparation of mesoporous silicon dioxide with high specific surface area

The influence of the reactant ratio on the specific surface area, total pore volume, and mean pore diameter of mesoporous silicon dioxide prepared by the sol-gel method was examined. The optimal reactant ratio for preparing the material with a high specific surface area was determimed.

Heterogeneous polymer materials based on oligodienetetraurethanediepoxide and oligoetherdiisocyanate

Based on mixtures of oligodienetetraurethanediepoxide and oligoetherdiisocyanate with low thermodynamic compatibility of the components, microheterogeneous elastomers are obtained and their properties are studied. The advantages of the new materials in strength and adhesion to steel over cross-linked elastomers based on individual oligovinylisoprenetetraurethanediepoxide are shown.