Influence of the UV radiation wavelength on the curing of oligourethaneacrylate compositions for protective coatings of optical fibers

The curing kinetics of films produced from compositions based on UV-curable oligourethaneacrylates is investigated using, as a source of radiation, an individual spectral line separated by a monochromator from the radiation of a DRT-400 mercury tubular lamp. It has been established that in the region of spectral sensitivity of the composition, the curing time of the film is inversely proportional to the intensity of volumetric absorption of the radiation-source photons by the initiator at the lower surface of the film under study. Individual contributions of some of the lines to the process of composition curing by using the integral spectrum of the radiation source have been evaluated. The spectral-kinetic results obtained were confirmed when using the compositions under study as protective coatings of optical quartz fibers.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 836–840, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Calculation of the detonation velocity of porous water-containing RDX-based charges

A nomographic method for predicting the detonation velocity of a porous explosive mixture prepared from RDX powder and water is proposed. It is shown that, in contrast to the existing calculation methods for predicting the detonation velocity, the use of the proposed nomogram greatly simplifies the procedure and requires knowledge of only two parameters: the mass fraction of RDX and the density of the mixture in the charge. At the same time, the nomogram is a coordinate system that enables to place and to compare on one field experimental data obtained at different parameters of the charge. It is shown that RDX powder-water hand-prepared charges can have a detonation velocity of 6–8 km/s. The detonation velocity of cylindrical water-containing charges 10–36 mm in diameter and 120–1000 mm in length with RDX mass fractions of 0.6–1.0 is measured.     

A Procedure for Measuring the Viscosity of Formulations Based on Oligourethane Acrylates for UV-Curable Protective Coatings of Fiber Light Guides

A capillary viscometric procedure was developed for measuring the viscosity of formulations based on oligourethane acrylates for UV-curable protective coatings of fiber light guides. The temperature dependences of the viscosities of these formulations were studied. The moduli of elasticity of fibers prepared from these formulations after UV curing were measured. These formulations can be stably applied, using a die, to the surface of fiber light guides in the course of their drawing at a drawing rate of up to 100-120 m min^-1.     

Orientation effect on the parameters of the polymorphic transformation of graphite under shock compression

A large effect of the shock compression direction with respect to the crystallographic planes of graphite on the detected pressure and rate of the transformation of graphite to a diamond or diamond-like high-pressure phase has been revealed. The effect is pronounced in more ordered graphite. The results indicate that shifts in basal planes complicate high-rate graphite-diamond transformation.     

Mechanism of amplification of convergent shock waves in porous media

The effect of amplification of moderate-intensity converging shock waves in porous media with decreasing initial density, revealed by numerically solving the hydrodynamics equations, was demonstrated for ID converging waves and for a 2D problem of the compression of porous material in conical solid targets. The latter problem was also treated within the framework of the simplest model of dynamic deformation of solids, with consideration given to shear stresses. The calculation results for porous graphite, aluminum, and Teflon samples are presented. Both closed targets and targets with an outlet orifice were considered. When modeling the intense shock loading of graphite, its transformation into diamond was taken into account.     

Calculation of shock compression of porous media in conical solid-state targets with an outlet hole

The Godunov-type method that was earlier developed for the hydrodynamic equations of compressible media on regular grids is extended to the case of shock wave flows in elastoplastic porous media. The results of numerical simulations of a hypothetical experimental plant for checking the effect of an increased intensity of converging shock waves in porous media with increasing degree of porosity are presented. This effect was earlier discovered by numerical simulations.