Diffusion Modification of Polymethyl Methacrylate with Oligoglycol Acrylates

The structural transformations of oligoglycol acrylates in the surface layers of polymethyl methacrylate were studied.     

Boson radiation in a periodic magnetic field

The first correction to the boson radiation intensity is obtained in an arbitrary two-component periodic magnetic field. In the ultrarelativistic case, the quantum correction for a specific kind of potential in which spiral motion is realized will agree with the corresponding expression in the theory of synchrotron radiation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 27–32, September, 1989.The authors are grateful to Prof. V. G. Bagrov for attention to the research.     

Properties of Bitumens Modified by Thermoplastic Elastomers

The possibilities of modification of bitumens by blend thermoplastic elastomers (TPEs) with predominantly maximum long main chains are studied. The evaluation of their properties shows that the blend TPEs display a stronger effect in low-viscosity bitumens, which is associated with improved compatibility of TPEs in bitumens, as evidenced by convergence of the solubility parameters of TPEs and of the aliphatic part of the malthene fraction of bitumens. The relaxation properties of the modified bitumens allow us to judge their stability under operating conditions, to evaluate this effect quantitatively, and to determine the activation energy of the relaxation process.     

Peculiarities of epoxide polymers modified with polychlorodiphenyl

The effect of polychlorodiphenyl (a low-molecular plasticizer) on the dynamic mechanical characteristics of epoxide polymers, namely, their strength, creep, and water absorption, are studied over a wide temperature range. Modification with polychlorodiphenyl is found to increase the rigidity and decrease the molecular-group mobility of a polymer, which correlates with changes in the physicomechanical properties. The effect of polychlorodiphenyl, different than that of other plasticizers, is explained here by a closer intermolecular coupling and a smaller free volume within the system, as has been confirmed by results of infrared spectrometry, as well as by measurements of density and sorptive properties.     

Radiation by bosons in a magnetic undulator of finite length

We have studied the effect of an undulator of finite length on the spectral-angular distribution of radiation with allowance for the first quantum correction. Such allowance is made by substituting the photon recoil for the factor gN familiar in classical electrodynamics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 54–58, October, 1989.     

Multimirror quasi-cylindrical cavity resonators for frequency-tunable gyrotrons

We consider the possibility to create a gyrotron with smooth mechanical frequency tuning on the basis of multimirror quasi-optical resonators. The two-dimensional problem of finding igenmodes at the open quasi-cylindrical resonator of such a type is solved. Parameters of the gyrotron based on such a device, namely, its efficiency and starting current, are estimated.