Creep of polymers during tension under conditions of hydrostatic pressure

Hydrostatic pressure results in decrease in the creep rate of a polymer loaded by tensile stress. The decrease in the creep rate is associated with the increase in intermolecular interaction. The correlation found between the creep rate of material loaded by a constant tensile force and with change in the melting temperature of a polymer under pressure appears to be commensurate with change in intermolecular interaction.A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 2, pp. 359–362, March–April, 1976.     

Effect of Carbonization Temperature and Activation on Structural Formation of Active Lignin Carbons

The effect of thermal and steam treatment on the oxidation state of surface functional groups formed in preparation of granulated carbons from cotton lignin was studied by means of IR spectroscopy and titration with bases of varied strength.     

Point Interaction Between Two Fermions and One Particle of a Different Nature

We consider a model of point interaction between two fermions and one particle of a different nature. The model is analogous to the Skornyakov–Ter-Martirosyan model. It is interpreted based on the self-adjoint extension theory for symmetric operators. We show that if the mass of the third particle is sufficiently smaller than the fermion mass, the corresponding energy operator has an infinite set of bound states with the energy values tending to –.     

Point interaction of two distinguishable particles in an external field

We consider a point interaction model for two particles in an external field, which is similar to the Skornyakov-Ter-Martirosyan model and is treated using the theory of self-adjoint extensions of symmetric operators. The corresponding energy operator has an infinite set of bound states with the energy values receding to-∞. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 125, No. 1, pp. 74–90, October, 2000.     

Gas-chromatographic investigation of the products of the thermolysis of hydrolysis lignin

Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. All-Union Scientific-Research Institute of the Chemical Technology of the Medical and Microbiological Industry, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 420–421, May–June, 1990.     

Lifetime levels and fracture of polyethylene terephthalate exposed to γ radiation and an aqueous medium

Conclusion 1. An analysis of the lifetime distribution curves obtained by varying the test conditions has revealed discrete lifetime levels in PETP due to the presence in the material of structural defects with different degrees of dangerousness. These defects are found at the edges, at the surface and in the interior of the specimens.2. Water affects irradiated and unirradiated PETP by reducing the probability of failure, rendering the structural defects less dangerous and, as a result, increasing the lifetime and impeding the fracture process.3. On the dose range investigated, rays affect PETP specimens by causing defects that reduce the lifetime and facilitate the fracture process, the defects produced becoming more dangerous as the dose increases.V. I. Lenin Tadzhik State University, Dushanbe. Translated from Mekhanika Polimerov, No. 6, pp. 1060–1064, November–December, 1978.     

Instability of the crystallites in oriented polymers under load

Large-angle x-ray diffraction and infrared spectroscopy have been used to investigate the behavior of the crystalline zones in oriented polymers under load. It is shown that under the influence of a load applied along the axis of orientation the crystallites are partially destroyed, the more so the greater the applied stress. For different polymers the destruction of the crystallites is the greater the weaker the intermolecular bonds. The stability of the crystallites is improved by orientation.A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 3, pp. 516–520, May–June, 1976.