Effect of organic polyelectrolytes on H*-aggregation of <Emphasis Type="Italic">meso</Emphasis>-methyl-substituted thiacarbocyanine dyes

H*-Aggregation of anionic meso-methyl-substituted thiacarbocyanines of different structures has been studied in dilute aqueous solutions and in the presence of cationic organic polyelectrolytes. The thermodynamic parameters of the H*-aggregation from the trans-dimers have been determined. The thermodynamic equilibrium between two forms of the H*-aggregates in the presence of poly-N,N-dimethyl-N,N-diallylammonium chloride has been observed for the first time, and these forms have been assigned to H* _cis and H* _trans forms.     

Mechanical serviceability and heat resistance of polymers

The research of the authors and coworkers on the serviceability and heat resistance of polymersis reviewed. The effect of the chemical and supermolecular structures on the heat resistance of poly (hetero-arylenes) is demonstrated with reference to numerous examples; methods of estimating the glass-transition and melting points, density, and volume expansion coefficients of polymers on the basis of the structural formula of the repeating unit are described.     

Some characteristics of the flow of polyisobutylene

The flow of polyisobutylene under a uniaxial constant tensile load has been studied over a broad interval of temperatures and stresses. In general, the isothermal flow curve (deformation-time) is divided by molecular rearrangement and crystallization into three sections, the first corresponding to flow in the amorphous state and the third, to flow in the crystalline state. The Kargin-Sogolova flow law describes well the first section and almost the third, but not the second section. The results obtained, together with those of an electron-microscope investigation, indicate that supermolecular structures play an important part in elastomer flow. The exhaustion of the lifetime of these structures also leads to a rapid development of deformation after a certain time t*_d (i.e., to the appearance of the second section of the flow curve). A relation analogous to the Zhurkov lifetime equation has been found among t*_d, the temperature T, and the true stress .Mekhanika Polimerov, Vol. 3, No. 4, pp. 659–666, 1967     

Study of mechanical relaxation processes in ladder organosilicon polymers

Dynamic viscoelastic properties of ladder polyorganosiloxanes have been studied by the method of induced resonance oscillations in the temperature range from –150 to 300°C and in the frequency range from 8 to 300 Hz. Two broad maxima of mechanical losses were observed for all the polymers studied independently of their chemical structure, a low-temperature maximum in the –150 to 0°C region and a high-temperature maximum in the 0 to 250°C region. It was found that the introduction of alkyl groups into polyphenylsilsesquioxanes does not noticeably affect the position and nature of the low-temperature relaxation peaks but in certain cases leads to an increase in the dynamic modulus in polyphenylalkylsilsesquioxanes, compared with the modulus of polyphenylsilsesquioxane in the same temperature region. In the high-temperature region, a distinct dependence is observed of the relaxation peak on the length and the content of alkyl groups in the polymer. It has been found that increase in the length and the content of alkyl groups is accompanied by a shift in the peak in the direction of low temperatures and a decrease in the value of the modulus. Hypotheses have been suggested on the nature of the shifts which lead to the relaxation peaks observed in the ladder polyorganosiloxanes.Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 5, pp. 804–809, September–October, 1973.     

Generalized temperature-time characteristic of the strength and hardness of amorphous polymer materials

A new generalized characteristic of the strength and hardness of amorphous polymer materials is developed using two geometric surfaces, viz., of strength and stress relaxation. The combination of these surfaces determines the service range of the polymer material. For the polyarylate of isophthalic acid and phenolphthalein the service range is determined exclusively by the strength surface.Mekhanika Polimerov, Vol. 1, No. 4, pp. 89–91, 1965     

Effect of polymetaphenylene isophthalamide (phenylon) structure on the properties of an antifriction material

The relationship between phenylon structure and the friction properties of a phenylon-based material is established using the data of friction tests, x-ray analysis, and electron microscopy. It is shown that amorphization of the binder structure leads to a change in the coefficient of friction and to a displacement of the zone of maximum operating temperatures in the direction of higher values.Institute of Hetero-Organic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 201–206, March–April, 1969.