Dynamic mechanical properties of multicomponent polymeric compositions

The mechanical relaxation processes in rubber-polymer compositions have been investigated by the forced nonresonance vibration method. A method of evaluating black-filled polymer mixtures with advantages over microscopic methods is proposed.Scientific-Research Institute of the Tire Industry, Moscow. V. I. Lenin Moscow State Pedagogical Institute, Laboratory of Problems in Polymer Physics. Translated from Mekhanika Polimerov, No. 1, pp. 138–141, January–February, 1970.     

Quasi-acoustic scheme for the Euler equations of gas dynamics

We suggest an original scheme and an algorithm for the numerical solution of the Euler equations of gas dynamics. The construction of the scheme is based on the mass, momentum, and energy conservation laws. The flux computation is carried out by summation of elementary fluxes formed by small-amplitude running waves that satisfy the linearized equations of gas dynamics. The scheme contains no artificial regularizers, has second-order accuracy on smooth solutions, and is quasimonotone in a neighborhood of the discontinuities. Examples of one- and two-dimensional computations are given.     

Reactions of some cyclic ketene acetals with maleic anhydride and acrylonitrile

The reactions of 9-methyl-4-methylidene-3,5-dioxabicyclo[5.4.0]undecane with maleic anhydride and acrylonitrile were studied by NMR spectroscopy and were found to give 1:1 molecular complexes with equilibrium constants of 0.24±0.06 and 0.14±0.04 l mol^?1, respectively. Analysis of the calculated (AM1) heats of formation ΔH, differences in the dipole moments Δμ, frequencies and intensities of stretching vibrations of the donor and acceptors, and charge distribution showed formation of π-π, mixed π-π-H, and H complexes with partial charge transfer. These complexes can be used in copolymerization of the above monomers.     

Synthesis and structure of mononuclear zinc complexes with pyridine-2-aldoxime

Three mononuclear different-ligand Zn(II) complexes, [Zn(CH₃COO)₂(PaoH)₂] (I), [Zn(PaoH)₂(DMSO)₂][BF₄]₂ (II), and [Zn(NCS)₂(PaoH)₂] (III) (DMSO = dimethylsulfoxide) were prepared by the reaction of zinc acetate and tetrafluoroborate with pyridine-2-aldoxime (PaoH). The composition and structure of the complexes were confirmed by IR spectroscopy and X-ray diffraction. All compounds crystallize in the monoclinic system, compounds I and II have space group P2₁/n, while compound III has space group C2/c. In all compounds, the Zn coordination polyhedron is a distorted octahedron, which is formed by the N₄O₂ sets of donor atoms in I and II and by N₆ in III. Complex I in the optimal concentration of 5–10 mg/L was found to stimulate the biosynthesis of standard (pH 4.7) amylases by the micromycete Aspergillus niger CNMN FD 06.     

Structure of associates of vinyl molecules and maleic anhydride in CCl<Subscript>4</Subscript> solution

The self-association of styrene, acrylonitrile, methylmethacrylate, N-vinylpyrrolidone, and maleic anhydride molecules is considered in dependence on the nature of the monomer, i.e., on the conjugation between functional groups. The AM1, Hartree-Fock (RHF), and density functional theory (DFT) methods of calculation are used in our investigations. Charge distributions on the atoms of interacting groups and contributions from overlapping molecular orbitals to the energy of formation of self-associates are found. The calculated parameters are compared with experimental data on absorption band shifts in IR spectra and on chemical shifts Δ_H and Δ_C for the hydrogen and carbon atoms of =CH, =CH₂, C=O groups of bound molecules in ¹H and ¹³C NMR spectra. The formation of π-H, CH…O, and CH…N bonds is proved. Analysis of CCl₄/monomer dependences shows that dimers are present in dilute solutions, while the presence of trimers in concentrated solutions cannot be excluded. Self-association constants are determined along with the degree of self-association, which lies within the range of 40–60% for 50 mol% of a monomer in solution.     

The structures of heteroassociates in mixtures of fluoromethacrylates with methyl methacrylate

An experimental and theoretical study of mixtures of 1,1,3-trihydroperfluoropropyl methacrylate and 1,1,5-trihydroperfluoroamyl methacrylate with methyl methacrylate showed the possibility of the formation of homo- and heteroassociates with various stabilities. The degree of association and intermolecular interaction energy depended on the composition of the mixture of monomers and the length of the fluoroalkyl substituent. The calculated electronic and energy parameters of the structure of associates were evidence of the polarization of the double bond of monomers in the formation of associates. The strongest polarization was observed in associates with ?ΔH between 7 and 27 kJ/mol. Temperature conditions for conducting radical processes with a maximum degree of the insertion of fluoromethacrylate units into copolymers were suggested.     

Copolymerization of styrene with acrylonitrile and maleic anhydride

The complex formation constants for styrene (donor)-acrylonitrile (acceptor) and styrene-maleic anhydride (acceptor) systems are found to be 0.19 ± 0.01 and 0.28 ± 0.01 l/mol (¹H NMR, CCl₄, 298 K); the same values are characteristic for three-component systems of these monomers. The calculated ΔH ₀ values (the AM1 method) for styrene-acrylonitrile (C₁) and styrene-maleic anhydride (C₂) complexes comprise ?1.24 and ?2.30 kJ/mol. Changes in charges on double bonds of complex-bonded molecules are in the range from 0.001 to 0.006 au. These values are typical of π-π complexes. By analyzing the composition and rate of bulk copolymerization (333 K, 0.03 mol/l AIBN), we have shown that two complexes are involved in chain propagation: r ₁ = $ k_{2C_1 } /k_{2C_2 } $ = 0.26 ± 0.015 and r ₂ = $ k_{3C_2 } /k_{3C_1 } $ = 4.17 ± 0.143.     

Adsorption and catalytic conversion of hydrocarbons on nanosized gold particles immobilized on alumina

Gold and nickel particles immobilized on alumina were prepared by the metal vapor synthesis and anionic adsorption methods. The dispersion of metals was determined by X-ray diffraction and transmission electron microscopy. The activity of nanoparticles, tested in model catalytic reactions of CCl₄ addition to multiple bonds and allyl isomerization of allylbenzene, changes in a wide range (from 1 to 3000 (mole of product) (mole of Au)⁻¹ h⁻¹) and is parallel to the chromatographically measured heats of adsorption of the corresponding unsaturated substrates. The heat of adsorption of unsaturated hydrocarbons can serve as a criterion for the efficiency of the gold-containing catalyst in olefin conversion. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2215–2218, October, 2005.