Bestimmung der sorptionsisothermen lösungsmittelfeuchter sorbentien nach der durchströmungsmethodeDetermination of sorption isotherms of solvent wetted sorbents by the through flowing method

The sorption isotherm is defined as the equilibrium moisture content of a sorbent as a function of the relative humidity at constant temperature. It is a measure for the hygroscopic behavior of the sorbent. In this work a simple and reliable method for the determination of sorption isotherms of solvent wetted sorbents is described. The sorption isotherm is determined by passing a nitrogen stream with a given relative humidity through a U-tube filled with the sorbent (through flowing method). The sorption isotherms of gas concrete, brick and clay for the sorbates isopropyl alcohol and water at 20 °C were measured. The reliability of the method was tested by comparing it with two other methods.     

Über die strukturbildung in polymerfilmen durch phasentrennung bei der filmbildung aus lösungen in löser-nichtlöser-gemischen

Phase separation during film formation of a thermoplastic copolymer from solution in mixtures of high-volatile solvents and low-volatile non-solvents was studied. The parameters determining the void volume of the microcellular films formed by phase separation are the non-solvent fraction, polymer concentration of the initial solution and difference in volatility between solvent and non-solvent. The microcellular structure depends on the time at which phase separation occurs during film formation.     

Der Begriff der hochwertigen Dichtung für lösbare Rohrleitungsverbindungen

Concept of High-Quality Seals in Disconnectable Pipeline Connections. The “Technical Instruction Air” of the Federal Republic of Germany stipulates the use of highquality gaskets in flange connections employed in handling of certain hazardous materials, but it gives no detailed informations concerning the high-quality criterion. This article gives reasons why the highquality criterion should be extended on all elements of disconnectable pipeline connections of various types which are to be evaluated as systems. It further discusses the basic aspect of quality management as well as the terms ?secluded emission”? and “diffuse emission”, which should be avoided or minimized respectively. The following criteria of high-quality pipeline connections are discussed: Design reserves, corrosion resistance, position fixing, safety against fracture without deformation, tightnessperiod and process hygiene.     

Entwicklungsstand und Perspektiven der Modellierung von Transportvorgängen in durchströmten Festbetten

New model equations enable the consistent and accurate calculation of heat transport, mass transport and chemical reactions in packed beds with fluid flow. The main features of this approach are reviewed and summarized, and selected aspects are discussed. The modelling approach may be a good starting point for the development of, for instance, membrane reactors and separation processes such as chromatography or freeze drying for thermally sensitive products.     

Untersuchung der rheologischen charakteristiken von lösungen aus polyacrylnitril-polymethylmethacrylat-gemischen in dimethylformamid

The influence of concentration and the conditions of preparations of fiber-forming solutions, containing a mixture of polyacrylonitrile-polymethyl methacrylate in dimethyl-formamide upon the rheological behaviour of the solutions and the rupture length of the films obtained thereof, have been investigated. The method of the “experimental design” was employed for this purpose. It was established that the obtained flow curves are satisfactorily described by the Ostwald model τ = K·γ^η. Regression equations were deduced concerning the influence of the total concentration of the solution, of polymethyl methacrylate in the solution, the agitation time, the speed of stirrer revolution, and the dissolution temperature upon the rheological coefficients K and n and the rupture length of the films. There follows from the analysis of these equations that the governing parameters may be chosen in such a way that K and n decrease, without markedly decreasing the rupture length.     

Anionische lösungspolymerisation von glycolid

The anionic solution polymerization of glycolid yielding polyglycolic acid was examined with several solvent-initiator-systems. The polymerization behaviour in toluene using the tertiary amines triethylamine and N,N-dimethylbenzylamine as initiators and in sulfolan (tetrahydrothiophenedioxide) with N,N-dimethylbenzylamine is described in dependence on initiator concentration and reaction time.     

Zur frage der gegenseitigen durchdringung von polymerknäueln in konzentrierten lösungen

The entanglement (mutual toothing) of random coils in concentrated polymer solutions was tested by crosslinking-reaction of two polybutylacrylate-copolymers A_x and A_Y. A_X is a copolymer of butylacrylate (BA) with the monoacrylic ester of butanediole (1–20 mole- % OH-groups) and A_Y is a copolymer of BA with isocyanatoethylacrylate (1–20 mole- % ? N ? C ? O). The maximum conversion U of this reaction, which can be realized, depends on the polymer content of the solution and on the content [X] of functional groups X or Y in the copolymer chains. By extrapolation of the experimental curves U ? f([X]) to [X] ? 0 the extent of the entanglement for non crosslinked random coils could be determined. It was found, that the toothing-zone increases with the polymer content of the solution from 0 (at 5 g polymer in 100 g solution) to about 20 % of the total volume of the swollen coils at 30 g polymer in 100 g solution, that is only a relatively small border zone of the coils.     

Methode zur Bestimmung der Wassertröpfchenverteilung in Wasser-in-Öl-Emulsionen

Method for the Determination of the Dispersion of Water-Droplets in Water-in-Oil-Emulsion (w/o-Emulsion) We find emulsions of the w/o type for instance in margarine and butter. Besides other facts the fine dispersion of the water in microscopical small droplets, which are coated by fat, are of importance. Therefore, it is of interest for the manufacturer that he has an exact idea of the dispersion of the water droplets in his product. We describe the method for the determination of the water dispersion and the preparation of the test material.     

Apparatur nach Baumann zur Bestimmung der Flüssigkeitsaufnahme von pulvrigen Substanzen

Baumann Apparatus for the Determination of Fluid Take Up by Powdery Substances It is possible with the apparatus described here to determine quantitatively the fluid take up by powdery substances for weights from 0.01 to 0.5 g. The process can be followed thereby optically by colouring the fluid. Moisture content, particle size of the substance to be examined and temperature of the liquid to be taken up is to be taken into consideration. The apparatus is simple, easy to work with and furnishes results in a few minutes. Sources of error are eliminated and the obtained values are reproducible.     

Eignung von kontinuierlich durchströmten Mischern zum Homogenisieren

Suitability of continuous flow mixers for homogenization. The homogenizing characteristics, calculation of power consumption, and the scope of continuous flow mixers are reported. An attempt is made to summarize the present state of knowledge in this area. Some experimental results are presented which have been obtained in the homogenization of gases or liquids in pipes and containers in which mixing was achieved by jets, built in flow-directing fittings, stirrers or a combination of these. The investigations extend from the laminar to the turbulent range of flow. A comparison of energy requirements for the various apparatus affords important data for the choice and design of continuous flow mixers.