Structure of the turbulent mixing zone on the boundary of two gases accelerated by a shock wave

Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 3, pp. 71–77, May–June, 1990.     

Synthesis and gas transport properties of polypentafluorostyrene

Polypentafluorostyrene (PPFS) (M _w = 1.7 × 10⁵ Da, M _w /M _n = 1.6, and Т _g = 110°С) has been synthesized by radical polymerization of pentafluorostyrene. The chemical structure of the polymer has been confirmed by ¹H and ¹⁹F NMR data. The permeability and diffusion coefficients of gases (He, H₂, O₂, N₂, CO₂, and CH₄) have been measured on a barometric setup. The permeability, diffusion, and solubility coefficients of gases have been shown to increase with the increases in the fluorine content in the repeat unit of the polymer in the polystyrene–poly(p-fluorostyrene)–PPFS series. Such behavior of transport parameters in the polymer series is associated with the growth in the fractional free volume and decrease in the cohesive energy density. The investigated polymers on the basis of styrene and its derivatives including PPFS are located in the middle of clouds of Robeson diagrams for N₂/CH₄, CO₂/CH₄, and O₂/N₂ and are not of interest for their separation.     

Effect of the phase transformations on acoustics of a mixture of gas with vapor,droplets, and solid particles

The propagation of acoustic waves in the two-fraction mixtures of gas with vapor, droplets, and solid particles of different materials and sizes with phase transformations has been studied. Nonstationary and nonequilibrium effects of the interphase exchange of the impulse, mass, and heat have been taken into account. A system of the differential equations of the motion of the mixture has been presented, and the dispersion relation has been deduced. The high- and low-frequency asymptotics of the attenuation coefficient have been obtained and analyzed. The effect of the heat and mass exchange on dispersion and dissipation of acoustic waves in the two-fraction mixtures of gas with vapor, droplet, and solid particles has been studied.