Time Positron Diagnostics of Metal β-Diketonates

The effects of the nature of the metal atom and -substituents in aluminum(III), chromium(III), cobalt(III), and iron(III) acetylacetonates on the lifetime and intensity of a long-lived component in positron and positronium annihilation were studied by the method of positron diagnostics. An addition of a positron to the -system of a chelate ring is supposed, which makes it possible to qualitatively estimate the basicities of the complexes. Annihilation of positrons and halogen-containing positronium -diketonates is accompanied by the formation of a protonated complex; for -organylthioacetylacetonates, annihilation follows the inhibition mechanism.     

Acid-base interactions and adhesion capacity in the system constituted by an epoxy coating and a metal

Free surface energy and acidity parameter of solid surfaces of polyepoxides used as anticorrosive coatings were measured. Formulations of epoxy resins with various curing agents were studied. The adhesion capacity of epoxy films to various metallic surfaces was evaluated.     

The correspondence of detachment characteristics and acid-base interaction measures

A quantitative estimate for the intensity of interphase acid-base interactions is proposed based on the acid and base parameters of the free surface energy of polymer adhesives and substrates of a different nature. An interaction between acid-base and strength characteristics of adhesive compounds is established. An increase in the adhesive strength with an increase in the difference between the surface acid and base properties of connected materials is revealed for a number of compounds (polyolefine-metal, rubber mixtures-brass, and Thiokol compounds-glass).     

Influence of colloidal structure of polymer mixes on adhesion strength of polyolefin compositions

Mixtures of low-density polyethylene and ethylene-vinyl acetate (EVA) copolymer are studied. It is shown that the adhesion value is defined by the polymer that forms a dispersion medium in the adhesive compositions and the type of fracture depends on the competing influence of the physical and mechanical parameters and the reduced acidity parameter of the polymer, which forms a continuous phase.     

Tributyl- or tribenzylbismuth-copper diacetate system as an alkylating reagent for alcohols

Tributyl- and tribenzylbismuth react with aliphatic alcohols in the presence of copper diacetate to give dialkyl ethers, with yields of 0.10–0.25 moles per mole of the organobismuth compound.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2109–2111, December, 1993.     

Coordination radical polymerization of methyl methacrylate,initiated by the azobis(isobutyronitrile)–tri-<Emphasis Type="Italic">n</Emphasis>-butylborane binary system

A procedure for coordination radical polymerization of methyl methacrylate in the bulk, initiated by the azobis(isobutyronitrile)–tri-n-butylborane binary system at 60°С, was developed. Butyl radicals participating in the initiation step were detected by EPR. These radicals are generated by complexation of cyanoisopropyl radicals with trialkylborane. The radical at the boron atom transforms from the C-centered to N-centered structure with the subsequent S_R2 reaction and fast generation of n-butyl radicals. As found by NMR and confirmed by kinetic studies, the tri-n-butylborane–initiator–monomer system stimulates generation of propagating poly(methyl methacrylate) radicals.     

Oxidative interactions of propene with acetic acid on a Pd-zeolite catalyst

The interactions between C₃H₆, AcOH and O₂ were investigated on 1.5 % Pd/TsVM catalysts prepared with and without addition of 15 % AcOK. Three states for surface oxygen on the promoted catalyst were distinguished. Two of them are involved in the oxidation of AcOH and C₃H₆ to CO₂ and H₂O, whereas the adsorbed species of the third type participates in the formation of allyl acetate. The O/Pd ratios for the promoted catalyst fall in the range from 3 to 4, the nonpromoted system is characterized by an O/Pd value of 0.5. IR-spectral data are used to discuss the reaction scheme for the formation of allyl acetate. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1721–1726, October, 1993.     

The Synergistic Effect of a Mixture of the Oligomer of 2,2,4-Trimethyl-1,2-Digidrochinoline and Polymeric Petroleum Resin on the Adhesion of Chlorobutyl Rubber to Steel

Studies have been carried out to increase the adhesion and heat resistance of insulating tape coatings based on chlorobutyl rubber applied on pipelines. It is shown that the synergistic effect of the growth of adhesion of chlorobutyl rubber to steel by the co-administration of the oligomer of 2,2,4-trimethyl-1,2-dihydroquinoline and polymeric petroleum resin is due to the increased interaction of the oligomer with chlorobutyl rubber under the action of a polymeric petroleum resin and the high adhesion of the oligomer to steel.