Preparation of copolymers of p-Isopropenylcalix[8]arene and Styrene

Summary p-Isopropenylcalix[n]arenes are useful building blocks for the design of novel polymer architectures. This paper is the first report on copolymerization of p-isopropenylcalix[8]arene and styrene by free radical polymerization. An extensive study on the optimization of the reaction conditions (especially monomer to initiator ratio, initiator concentration, and duration of the process) was performed in order to prepare high molecular weight copolymers in good yield. Homopolymerizations were also carried out for comparison. The products obtained by homopolymerization of the monomers and their copolymerization were fractionated and each fraction was characterized by chromatographic (GPC and HLPC) and spectroscopic methods as UV, IR and ¹H NMR and analytical methods. Considering the molecular weight, spectroscopic and analytical data the most probable structure of the copolymer was proposed. Extraction of metal picrates from water into organic solvent was used to evaluate the ion binding capabilities of p-isopropenylcalix[8]arenestyrene and O-acetylated p-isopropenycalix[8]arenestyrene copolymers.     

Investigation of the processes of obtaining plastic treatment and electrochemical behaviour of lead alloys in their capacity as anodes during the electroextraction of zinc I. Behaviour of PbAg, PbCa and PBAgCa alloys

The influence of the mode of obtaining and plastic treatment of binary PbAg and PbCa, and ternary PbAgCa alloys (used as anodes in Zn electro-extraction from sulphate electrolytes) on their electrochemical behaviour and corrosion resistance is studied.It has been established that the rolled PbAg alloys possess a higher corrosion resistance and lower anodic polarization compared to the cast lead-silver ones due to the structural fineness and homogeneity of the plastic deformed anodes. The plastic deformation of the ternary alloys with calcium content of 0.06% causes Pb₃Ca precipitation in the solid solution. The hot-rolled alloys form an solid solution of Pb₃Ca with fine-grained structure, deformed through the rolling direction. The cold-rolled alloys possess clearly expressed oriented structures also through the rolling direction.Cast and plastically deformed PbCa anodes possess better electrochemical and corrosion characteristics than pure Pb but a considerably higher anodic polarization and lower corrosion resistance than PbAg alloys. Both PbCa systems, with a calcium content of 0.08 and 0.11 % are very appropriate for the preparation of ternary PbAgCa alloys. These alloys (PbAg 0.5 %-Ca 0.11 %) possess better electrochemical and corrosion characteristics than binary PbCa ones. Only ternary rolled alloys have equal corrosion and electrochemical properties to those of the alloy PbAg (0.75%–1.0%) used in practice.     

Superplastic ductility of oxide and nonoxide ceramics

The superplastic ductility of oxide and nonoxide SHS ceramics is considered. It is established that with certain temperature-rate dependences these ceramic materials manifest features typical of superplastic flow. It is shown that the ceramics undergo some specific microstructural changes under strain conditions.Institute of Problems of Metal Superductility, Russian Academy of Sciences, Ufa. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 5, pp. 617–622, November, 1993.