Immobilization of disperse red 1 onto polydiethyleneglycol-bis-allylcarbonate (CR-39) radiation grafted with poly(acryloyl chloride)

Abstract Acryloyl chloride (AC) was radiation grafted from 30% solution of monomer in toluene onto polydiethyleneglycol-bis-allylcarbonate (CR-39) by their simultaneous -iradiation. The grafting process was more efficient at dose rate of 4.4 kGy/h as compared with 0.4 kGy/h, and grafting values of 15-18% were achieved at 2.2-5.5 kGy. Subsequent immobilization of disperse red 1 (DR1) onto the grafted polymer was carried out from 0.02 M solution of this dye in dichloroethane, and the immobilized DR1 yield increased with the grafted polyAC value. Surfaces of the starting and modifed CR-39 were characterized with the FTIR-ATR spectroscopy and atomic force microscopy. An essential difference in chemical structure and topography of the CR-39 surface before and after the DR1 immobilization has been shown. The colourless plates of CR-39 became red after the DR1 immobilization, and the color intensity increased with the dye content. Changes in visible absorption spectra of the immobilzed DR1 caused by the photoinduced trans-cis isomerization of this dye were discussed.     

Flame propagation in a closed deformable channel

Izhevsk. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 3, pp. 27–33, May–June, 1990.     

Volumetric (PVT) and Calorimetric (C V VT) Measurements for Pure Methanol in the Liquid Phase

Volumetric (PVT) and calorimetric (C _V VT) properties of pure methanol were measured in the liquid phase with a twin-cell adiabatic calorimeter. Temperatures were measured in a range from 314 to 411 K, densities between 699.3 and 775.6 kgm^–3, and pressures to 20 MPa. The calorimetric cell (70 cm³ capacity) was surrounded by adiabatic thermal shielding (high vacuum). The sample pressures were measured by means of a quartz crystal transducer to within an uncertainty of about ±7 kPa. The relative uncertainty of C _V was estimated to be 2%, with a coverage factor k = 2, by combining the various sources of experimental uncertainty using a root-sum-of-squares formula. The results for pure methanol were compared with other recent measurements performed with a second high-temperature, high-pressure adiabatic calorimeter. Deviations of less than 3% were found between the earlier C _V data and the present results for pure methanol. The uncertainty of the density measurements was estimated to be 0.2% (k = 2). The measured densities and isochoric heat capacities were compared with values calculated with an IUPAC equation of state. Agreement of density was within 0.088% and that for isochoric heat capacity was within 0.95%. Values of vapor pressure were determined by extrapolating experimental P–T data to the saturated temperature along a fixed isochore. In the temperature range of this study, decomposition of methanol was not observed.     

Type of hydrocarbon activation and nature of active sites of base catalysts in methane oxidative dehydrodimerization

Methane activation on magnesium-oxide-cased catalysts for methane dehydrodimerization has been studied. As found, the rate of dehydrodimerization changes proportionally with the concentration of base sites on the catalytic surface. The activation of methane results in the formation of the methyl anion, as ascertained by IR-Fourier spectroscopy. The dehydrodimerization rates have been compared with the concentration of one-electron sites and the rate of the CH₄---CD₄ isotope exchange. Based on the data obtained a new mechanism of methane dehydrodimerization has been proposed; at the first reaction step a fast heterolytic dissociation of methane on base sites takes place. The rate-determining step is that of the metal-methyl dissociation leading to the formation of the methyl radical which determines a high activation energy of methane dehydrodimerization on oxide catalysts.