Study of the formation of polyimide from complexes of benzophenonetetracarboxylic acid diester with different diamines. 2. Features of thermal imidization of the molecular complex of benzophenonetetracarboxylic acid diester with 2,6-diaminopyridine

H-bond complexes of benzophenonetetracarboxylic acid dimethyl ester with 2,6-diaminopyridine (BZPE·DAP) have a dimeric structure in which one of the amino groups of the diaminopyridine participates in the formation of an H bond and the other does not form strong intermolecular bonds. During thermal imidization, the relative reactivity of the free amino group is lower than the reactivity of the group bound in the complex. In the BZPE·DAP system, 10% of the free amino groups remain after completion of imidization and they disappear at a high temperature. It is hypothesized that they can participate in the formation of interchain imide bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 530–533, March, 1990.     

Interaction of shock waves during the passage of a disrupted meteoroid through the atmosphere

The motion of fragments following disintegration of a meteoroid during its flight through the Earth's atmosphere is investiated. Shock wave configurations, aerodynamical forces and moments acting on each fragment and the trajectories of the pieces are determined for hypothetical initial configurations. The results of numerical simulations show that a meteoroid's breakup may lead to both increase and decrease of the total cross section, drag forces and energy release in the atmosphere. As a consequence the emitted radiation varies.     

Investigation of the role of the pyrimidine ring in the main chain of polyamido acids and polyimides. 2. Characteristics of the thermocyclization of polypyromellitamido acids based on 2,5-bis(p-aminophenyl)pyrimidine and 4,4′-diaminoterphenyl

The thermocyclization of polypyromellitamido acids based on 2,5-bis(p-aminophenyl)pyrimidine and 4,4-diaminoterphenyl was investigated by thermogravimetric and mass spectrometric analysis. Characteristics of the thermocyclization of pyrimidine-containing polyamido acids due to the presence of a basic nitrogencontaining ring in the main macrochain were revealed. The hypothesis advanced in Part 1, that the pyrimidine ring displaces solvent molecules bound to the polyamido acid, was confirmed. The hypothesis of the presence of shift packing in a pyrimidine-containing polyamido acid was confirmed by its greater kinetic homogeneity in comparison with the completely aromatic analog.Institute of High-Molecular-Weight Compounds Russian Academy of Sciences, 199004 St. Petersburg. Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2297–2301, October, 1992.     

The study of the structure of solutions of the H-complexes of diesters of tetracarboxylic acids with diammes by the light scattering method

The process of structurization in solutions of H-complexes of dimethyl 3,3,4,4 -benzophenonetetracarboxylate with 4,4 -diaminodiphenylmethane has been investigated in 90 % aqueous methanol in the concentration range 6 to 0.2 g L^–1. Structural instability of the solutions has been found in the concentration range from 1.2 to 2 g L^–1. The addition of an ionogenic substance stabilizes the solution and results in monotonic changes in the structural parameters as solution is diluted. A tendency toward variation of the extemum in the mean correlation radius of the polarizability fluctuation has been found in the concentration range 0.6-–1 g L^–1, which had been observed previously for polymer systems.For Part 1, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1219–1221, July, 1994.     

Viscosity of Melts of H Complexes Based on Acidic Diesters of Benzophenonetetracarboxylic Acid and Diaminodiphenylmethane or m-Phenylenediamine

The time dependences of the viscosity of melts of H complexes formed by dimethyl or diethyl dihydrogen 3,3',4,4'-benzophenonetetracarboxylate and 4,4'-diaminodiphenylmethane, m-phenylenediamine, or equimolar mixture of these diamines at 95 and 105°C were studied.