A multivariate analysis of the IR spectra of tetrazole-containing copolymers

Copolymers of acrylic acid and 5-vinyltetrazole are studied by IR Fourier spectroscopy and by multivariate analysis of their IR spectra. It is found that the changes in the intensity of spectral peaks of the samples studied correlate with the conditions of obtaining of these copolymers.     

Formation of composite scaffolds based on chitosan and calcium phosphate

Composite materials based on chitosan and calcium phosphates with the structure and properties close to those of natural human tissues were developed. The possibility of formation of biological apatite, i.e., octacalcium phosphate, was demonstrated. The increase in the strength characteristics was caused by crystallization of the octacalcium phosphate phase on the surface of the material pore space. The materials resemble the extracellular matrix of the body in their structure and composition and can find wide use in the regenerative medicine as a scaffold for osteogenic factors.     

X-ray diffraction study of ceramic samples of SrCu1/3Nb1/3O3

Ceramic samples of SrCu_1/3Nb_2/3O₃, obtained either by slow cooling or by quenching from 1200°C, were studied by X-ray diffraction using the Rietveld method. The slow-cooled SrCu_1/3Nb_2/3O₃ samples contain one phase with a perovskite structure (R _B = 4.14%, tetragonal crystal symmetry, space group P4/mmm, Z = 1, a = 3.935 ?, c = 4.124 ?), its diffraction peaks being considerably broadened. The samples quenched from 1200°C contain two SrCu_1/3Nb_2/3O₃ forms with a perovskite structure: one of them is oxygen deficient (R _B = 3.37%, tetragonal crystal symmetry, space group P4/mmm, Z = 1, a = 3.9687 ?, c = 4.0718 ?), and the other has no oxygen deficiency (R _B = 3.20%, tetragonal crystal symmetry, space group P4/mmm, Z = 1, a = 3.95307 ?, c = 4.08935 ?).     

Calculation of thermal conductivity of filled oligomeric compositions

Different models for the calculation of thermal conductivity of oligomeric compositions filled with a dispersed filler (silicon carbide) are studied. It is shown that the calculated values of thermal conductivity of oligomeric compositions with introduced dispersed filler provided by the van Krevelen model developed for the calculation of thermal conductivity of unfilled amorphous polymers with isolated regions of the crystalline phase are the closest to the experimental ones.     

Behavior of Tetrazole-containing Acrylic Hydrogels in Electrolyte Solutions

The influence of temperature, pH, and chemical composition of the medium on the equilibrium swelling of polymeric polyelectrolytic tetrazole-containing acrylic hydrogels was examined.     

Composites based on vinyl tetrazole-acrylate copolymers and hollow glass spheres

Hydrogel composites based on sodium acrylate, 2-methyl-5-vinyltetrazole, and N, N- methylenebisacrylamide, modified with hollow glass spheres during radical polymerization were prepared and studied. The influence of the modifying additives on the physicochemical properties of the composites was elucidated. A mechanism of modification of vinyl tetrazole-acrylate copolymers with hollow glass spheres was suggested. The materials synthesized are suitable for preparing articles with desired shape and good performance characteristics.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 10, 2004, pp. 1719–1721.Original Russian Text Copyright ¢ 2004 by Uspenskaya, Sirotinkin, Masik.     

Model of formation of three-dimensional polyurethane films modified by detonation nanodiamonds

The possibility of increasing the strain resistance of three-dimensional polyurethane films modified by detonation nanodiamonds is analyzed. It is found that the physicomechanical characteristics of polyurethane foams modified by nanodiamonds at a content of several thousandths of a weight percent change significantly. Models of the hardening of polyurethane films are proposed.     

Synthesis and Absorption Power of New Polyelectrolyte Tetrazole-Containing Acrylic Hydrogels

The kinetic features of formation and equilibrium swelling in water and aqueous solutions of metals were considered for new hydrogels based on acrylic acid and methylenebisacrylamide modified with 2-methyl-5-vinyltetrazole in the polymerization stage. The influence of the concentration of the reactants on the gelation rate and the degree of equilibrium swelling was studied, as well as the influence of 2-methyl-5-vinyltetrazole on the properties of the copolymers prepared. Possible application fields for the new hydrogels were proposed.     

Investigation of double sulfates of lithium and rare earth elements

Compounds in the system Li₂SO₄R₂(SO₄)₃, where R is a rare earth element, have been investigated. Only compounds of the type LiR(SO₄)₂ are formed. The existence of three structural types has been established. X-Ray parameters from Nd to Er have been determined. The thermal stability of the compounds has been investigated.