Modification of the Surface of Magnetic Iron Oxides with Phosphonic Complexones

Protection of Metals and Physical Chemistry of Surfaces - The conditions of chemical modification of the surface of synthetic magnetic iron oxides (magnetite Fe3O4, maghemite γ-Fe2O3) by...     

Synthesis,structure and behavior of new polycaprolactam copolymers based on poly (ethylene oxide)–poly (propylene oxide)–poly (ethylene oxide) macroactivators derived from Pluronic block copolymers

Novel series of poly (CL–co–Pluronic) polymers were successfully synthesized in situ by ring-opening polymerization (ROP) of ε-caprolactam (ε-CL). The copolymerization was activated by new type macroactivators (MAs) based on hydroxyl-terminated poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) [PEO-PPO-PEO] triblock copolymers, known under the trade name Pluronic^®. Toluene-2,4-diisocyanate (TDI) was used to obtain the isocyanate-terminated Pluronic prepolymers. The corresponding MAs were synthesized in situ with an N-carbamoyllactam structure. As an initiator of the copolymerization processes was used sodium lactamate (NaCL). To confirm the influence over the copolymerization process, microstructure, composition and molecular weight of the polymeric products two new types MAs based on Pluronic (P123 and F68) have been varied from 2 to 10 wt.% (vs. the monomer ε-CL). The structure of the both Pluronic based macroactivators (MAs) and accordingly obtained two series poly (CL-co-Pluronic) polymers were confirmed by ¹H NMR and FT-IR analyses. Additionally, the structure, molecular weight, physicomechanical behavior, thermal stability and morphology of the new synthesized poly (CL–co–Pluronic) polymers have been investigated by Differential Scanning Calorimetry (DSC), Wide-Angle X-ray Diffraction (WAXD), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) analysis.     

Dispersely filled heterocyclic polyamide fibre with properties of high-temperature superconductivity

Fibres and films with the properties of a high-temperature superconductor were fabricated by spinning from dispersions of HTSC ceramic thickened with aromatic polyamidobenzimidazole and subsequent firing. The events that take place during fabrication of fibres and films were investigated by electron microscopy, DTA, TGA, and EPR. The important possibility of superconductivity in the PABI-HTSC ceramic system with a degree of filling greater than 60 wt. % was demonstrated. Translated fromKhimicheskie Volokna, No.6,pp.l4–18, November–December, 1998.     

The forest biorefinery and its implementation in the pulp and paper industry: Energy overview

Incorporating a biorefinery unit to an operating Kraft pulping process has significant technological, economic and social advantages over the construction of a grassroot biorefinery. Also, the conversion of a Kraft mill from total pulp making to complete biorefinery can be done in a stepwise fashion and so give a company that envisages such transformation the opportunity to master the new technologies, evaluate options and develop an appropriate business plan. In all cases however, the road to conversion presents serious challenges. As components of the wood such as lignin or hemicelluloses are withdrawn from the Kraft pulp line, the heat production capacity from the recovery boiler where they are currently burnt is diminished. At the same time the operation of the added biorefinery unit increases the steam demand. In order to avoid fossil fuel dependency, the total site must be highly integrated and optimized. The application of an intensive and innovative energy optimization methodology to actual case studies has shown that the green, low GHG emissions biorefinery is feasible. The economics can be attractive for a site combining specialty wood pulp and bio-product, biomass gasification, power cogeneration and heat upgrading by optimally positioned and designed absorption heat cycles. The methodology has been applied to biorefining technologies for lignin and hemicelluloses extraction and valorisation, both technologies being coupled with gasification of wood residue.     

Optimizing the structure of six-port transducers

Translated from Izmeritel'naya Tekhnika, No. 3, pp. 37–38, March, 1991.     

Diode Detector Development for 12-Terminal UHF Circuit Analyzers

Parameters have been determined for a diode detector that reduce the error in measuring UHF network characteristics by means of 12-terminal devices.     

Phase behavior of gelatin in the presence of pectin in water-acid medium

Summary Phase separation of alkaline gelatin in water-acid solutions in the presence of low etherified pectin (ED 38%) were investigated. The effects of the pectin weight fraction in pectin/gelatin mixture (q_o) as well as two conditions of complex formation, namely, mixing of the binary biopolymer-solvent systems at pH 3.5 (‘mixing conditions’), or preparation of the ternary gelatin-pectin-water systems at pH 7.5 and their subsequent acidification up to pH 3.5 (‘titration conditions’), on phase equilibrium and macrostructure of the concentrated complex phase were established using phase analysis, and optical microscopy. At q_o<0.5 the aggregative phase separation was observed in both conditions of complex formation leading to the almost complete concentration of both biopolymers in the bottom phase at q_o=0.3 (‘mixing conditions’) and at q_o=0.5 (‘titration conditions’). At q_o>0.5 unusual three phase separation took place in the ‘mixing conditions’, leading to formation of supernatant (phase 1), complex coacervate (phase 2) and concentrated pectin solution (phase 3). Possible mechanism of such phenomenon was discussed in term of segregative and aggregative phase separations.