Content of double bonds in polyethylene

The content of double bonds in high-pressure polyethylene of various brands obtained from Russian and foreign manufacturers was studied. The essence of the method was to build a calibration curve on an infrared Fourier spectrometer for standard substances with a previously known arrangement of the double bond, saturation of double bonds in the initial polyethylene using gaseous bromine, and subsequent assessment of the locations and number of double bonds in the studied brands of high pressure polyethylene. The calibration substances were trans-4-decene with a purity of 96%, 1-decene with a purity of 95%, and 2-methyl-1-heptene with a purity of 98%. To record infrared spectra, calibration substances were dissolved in carbon disulfide with a purity of 99.5%. The spectra of the calibration substances were recorded in the transmission mode. The recording of the spectra of the high-pressure polyethylene samples was carried out in the reflection mode. To calculate the molar adsorption coefficient of individual calibration substances, the areas of the peak absorption of individual substances were allocated. The Peak Separation NETZSCH software was used for this purpose. For all analyzed samples, both brominated and not brominated, the ratio of the areas of absorption peaks was calculated. For each sample of high-pressure polyethylene, the content of trans-vinylidene, vinyl, and vinylidene groups C=C per 1000 carbon atoms was determined. The total number of double bonds was calculated as the sum of all analyzed bonds contained in the polyethylene sample. The accuracy of the analysis method performed by a single laboratory on a single sample is ±10% of double bonds per 1000 carbon atoms. The technique allows one to evaluate such a characteristic of low density polyethylene as the content of double bonds. This characteristic is essential for the efficient development of crosslinkable polyethylene compounds.

APPLICATION OF REGRESSION ANALYSIS FOR CALCULATIONS UNDER DATA OF IKFS-2 AND MTVZA DEVICES OF METEOR-2 SATELLITES

This article examines a multiple regression method to calculate the characteristics of the at-mosphere with hyper spectral sensors data of “Meteor-2” satellite. The method was used to calculate the carbon dioxide concentration by infrared Fourier-spectrometer IKFS-2 and the integral content of water vapor of atmosphere for the microwave sensor MTVZA-GY. Analysis of the obtained results and calculation errors showed the possibility of using this method to restore the values of atmospheric parameters. The proposed method could be applied to for various sensors and it allows to expand the capabilities of other methods.

Case study of ozone anomalies over northern Russia in the 2015/2016 winter: measurements and numerical modelling

Episodes of extremely low ozone columns were observed over the territory of Russia in the Arctic winter of 2015/2016 and the beginning of spring 2016. We compare total ozone columns (TOCs) from different remote sensing techniques (satellite and ground-based observations) with results of numerical modelling over the territory of the Urals and Siberia for this period. We demonstrate that the provided monitoring systems (including the new Russian Infrared Fourier Spectrometer IKFS-2) and modern three-dimensional atmospheric models can capture the observed TOC anomalies. However, the results of observations and modelling show differences of up to 20 %–30 % in TOC measurements. Analysis of the role of chemical and dynamical processes demonstrates that the observed short-term TOC variability is not a result of local photochemical loss initiated by heterogeneous halogen activation on particles of polar stratospheric clouds that formed under low temperatures in the mid-winter.