Zum Fließverhalten von kurzglasfasergefüllten Styrol-Acrylnitril-Copolymeren

The viscosity of high polymer melts increases usually when adding fibres. Such an increase has been measured for a short fibre reinforced styrene/acrylonitrile copolymer with 25 and 35% (by weight) glasfibres on a rotational viscometer in the range of shear rates from 10^?3 to 10¹s^?1 for different temperatures and pressures. The viscosity curves show a zero shear viscosity. Its dependence on temperature, pressure and concentration of fibres can be described by straight lines. Furthermore it is possible to shift the viscosity curves in a way that they form a temperature- and pressure-independent, and even a concentration-independent master curve.     

Fließverhalten von Mischungen aus chloriertem Polyethylen und Polymethylmethacrylat

The flow behavior of bicomponent polymer blends of chlorinated polyethylene (PEC) and poly(methyl methacrylate) (PMMA) is presented in the form of flow curves. The relations between the rheological measurements and the morphology are discussed. The blends (PEC/PMMA, chlorinated up to 40 wt.-%) show the characteristic behavior of incompatible systems, some of them with a second highly dispersed phase. In addition a system of PE/PMMA is examined, the PE being the raw material of the PEC. The influence of the chlorination on flow behavior and the biphase structure is obvious.     

Neue Ergebnisse zum Fließverhalten von konzentrierten Polymerlösungen

A variety of measurements mainly using solutions of polystyrene and polyvinylacetate has been made to investigate the correlation between viscosity of concentrated polymer solutions and both the properties of all components of the solution and the experimental conditions. The following parameters have been changed: polymer concentration, molecular weight, temperature, shear and chemical structure of the solvents. In addition some measurements have been made using solutions of ethylene-propylene-copolymer, chlorinated polypropylene, polyvinyl alcohol and methylcellulose. Various polymer systems have also been investigated using mixtures of solvents. Data from the literature are reported supplementary to our measurements. It is shown that the results can be explained qualitatively on the basis of physical considerations. Such considerations allowed to predict new effects, for which experimental evidence could be obtained. New correlations with other material properties have been found. Thus we regard these facts as a strong support for the usefullness of our concept.     

Fließverhalten pastöser,fetthaltiger Massen

Flow Properties of Pasty and Fatty Fluids Experiments with a specially developed tube viscosimeter are reported in which flow properties of pasty and fatty fluids depending of pressure, temperature, recipe, crystallisation conditions and tube diameter were determined. It is shown, that a combination of the power law and Bingham equation describes the flow properties of such kind of fluids. With the help of the gained results it is possible to get data to lay out machines for dosing and transporting pasty and fatty fluids.     

Die Fließeigenschaften von Emulsionen

The Flow Properties of Emulsions The resistance of emulsions to flow is decreased by the temporary shearing strain (e. g. stirring). This phenomenon, called thixotropy, is due to the internal structure built by the emulsified particles. The structure is reversibly destroyed by the application of force. Sufficiently strong skeleton-formation gives a pasty consistancy to the emulsion. A definite force (yield point) is required to make it flow. A practical example of this is mayonnaise. The strength of the structure formation is essentially dependent on four factors: 1. The concentration of dispersed phase, 2. the degree of dispersion, 3. the nature of the emulsifying agent and 4. the nature of the external phase. For the measurements of the flow properties a rotary-viscometer is used.