Preparation of magnetic poly(glycidyl methacrylate) microspheres by emulsion polymerization in the presence of sterically stabilized iron oxide nanoparticles

With the aim to synthesize water‐dispersible superparamagnetic nanoparticles, iron oxide was precipitated in aqueous solution of dextran, (carboxymethyl) dextran (CM‐dextran), (DEAE‐dextran), or D ‐mannose. Glycidyl methacrylate (GMA) was emulsion‐polymerized in the presence of the nanoparticles and the effect of iron oxide modification on the product properties was investigated. The main factors affecting the morphology, size, and size distribution of the latex particles are the type and concentration of emulsifier (Disponil AES 60, Tween 20, Triton X‐100) and initiator [ammonium persulfate (APS) and 4,4′‐azobis(4‐cyanovaleric acid) (ACVA)]. Disponil AES 60 and ACVA are the preferred emulsifier and initiator, respectively, because oxirane groups hydrolyzed during the APS‐initiated polymerization. Up to some 5 wt % of iron was found in poly(glycidyl methacrylate) (PGMA) microspheres obtained by emulsion polymerization in the presence of dextran‐coated iron oxide and emulsified with Disponil AES 60. The size of magnetic PGMA microspheres could be controlled in the range ? 70–400 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4348–4357, 2006     

Structural-morphological features of yarn spun from a polyarylenesulfone oxide-polyamidobenzimidazole mixture

Conclusions -- The structural-morphological features of yarns spun from a mixture of fusible polyarylenesulfone oxide (PASO) and polyamidobenzimidazole (PABI) have been studied.-- It has been shown that in yarn containing from 1 to 15% by wt. of PABI belongs to two-phase disperse systems of the matrix type in which the birefringent PABI phase is dispersed in an isotropic matrix consisting of the fusible PASO component.-- It has been found that in freshly spun PASO-PABI yarn at a weight ratio of 60:40 or 50:50, the PABI retains a high degree of molecular orientation, but the PASO is in a weakly oriented state.VNIIPV, Mytishchi. Translated from Khimicheskie Volokna, No. 3, pp. 14–17, May–June, 1992.     

State of manganese atoms in the Nd1+x Sr2−x Mn2O7−δ solid solution

The oxidation state of manganese in the Nd_2?x Sr_1+x Mn₂O_7?δ solid solution was determined by X-ray photoelectron spectroscopy and by calculating the oxygen nonstoichiometry based on the gravimetric data. As a result of the heterovalent replacement of Nd³⁺ with Sr²⁺, the change in the oxidation state of manganese occurs in different ways, i.e., it increases at x > 0 and decreases at x < 0. In the latter case, some oxygen ions acquire the oxidation state of ?1. The samples slowly cooled under oxidative conditions possess a significant positive oxygen non-stoichiometry, which tends to decrease after Nd³⁺ is replaced with Sr²⁺. An excess of oxygen stabilizes the crystal structure of Nd_1+x Sr_2?x Mn₂O_7?δ.     

Clinoptilolite/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>: a magnetic sorbent for removing <Superscript>90</Superscript>Sr from aqueous media

The ability of a magnetic sorbent prepared by modification of clinoptilolite with magnetite to take up ⁹⁰Sr was studied. ⁹⁰Sr is sorbed most efficiently at pH in the range 6–9. At the sorbent dosage of 5 g dm^–3 and sorption time of 24 h, the degree of ⁹⁰Sr sorption from aqueous solution is as high as 99.8%.     

Modification of the organic matter of brown coals with nitrous oxide

The results of the treatment of brown coals from the Kansk-Achinsk Basin in an atmosphere of nitrous oxide are given. It was established that the main products of nitrous oxide interaction with the organic matter of brown coal are soluble low-molecular-weight products (ketones and aromatic acids) and oxodiazoline structures in a coal matrix. The thermal-oxidative degradation of terminal oxygen-containing groups, which accompanied this process, facilitated the formation of strong crosslinks and the strengthening of a supramolecular structure.     

Diffusion welding of 12Cr18Ni10Ti steel to palladium alloy foil

The special features of the method of diffusion welding of corrosion-resisting steel with a palladium foil using an intermediate layer made of nickel are presented. The method can be used for producing full-strength and vacuum-tight welded joints.     

High-temperature oxidation of nickel-based alloys and estimation of the adhesion strength of resulting oxide layers

The kinetics of isothermal oxidation (1100°C) of commercial nickel-based alloys with different content of sulfur (0.22–3.2 wt ppm) is studied. The adhesion strength in a metal/oxide system is estimated as a function of sulfur content and duration of high-temperature exposure. The scratch-test technique is proposed to quantitatively estimate the work of adhesion of resulting oxide films. It is found that the film microstructure is composed of an inner α-Al₂O₃ layer and an outer NiAl₂O₄ spinel layer, which are separated by discrete inclusions of TiO₂. Residual stresses in the oxide film are experimentally determined by X-ray diffraction.