Ein beitrag zur polymerisation von hexamethylenoxid

Hexamethyleneoxide (HMO) polymerizes in the presence of LEWIS acids and epoxides to yield high molecular weight products. The heat of polymerization is approximately — 3 kcal/mole. Copolymers with ethyleneoxide were obtained. The initial rate of polymerization for tetrahydrofuran is higher than for HMO.     

Versuche mit zur Produktion von Erucasäure geeigneten Kulturarten

Experiments with Oilseed Crops for the Production of Erucic Acid The Brassica-species are well suited for the production of erucic acid as industrial raw-material. The five crop species Indian mustard (Brassica juncea), Äthiopian mustard (Brassica carinata), Crambe (Crambe abyssinica), oilseed radish (Raphanus sativus ssp. oleiformis) and rocket (Eruca sativa) were tested for agricultural and seed quality characteristics. The results of the primary evaluation showed that quality is sufficient in all crops besides oilseed radish; however the starting yield level is only satisfying in Indian mustard and Crambe. It was possible to increase yields significantly in crossing progenies. As all species are summer types, their yield potential ist naturally lower than that of winter rapeseed.     

Versuche zur pfropfung von polystyrol auf rußoberflächen

Polybutadiene-based high impact polystyrenes show in comparison to standard polystyrene a significant reduced weather-resistance. An effective stabilization of the twophase material with dispersed carbon black is accompanied by a notch effect of the pigment in consequence of a lack of carbon black-polymer compatibility. This notch effect influences the main advantage of the high impact polystyrene, which is its excellent toughness. This paper reports on experiments to improve the compatibility of carbon black-polymer by grafting polymer chains onto the carbon black surface.     

Versuche zur darstellung von poly-2,6-dimethylphenylenäther mit suspendiertem katalysator

Experiments to prepare poly-2,6-dimethyl-1,4-phenylenether (DMPPO) by oxydative coupling of 2,6-dimethylphenol have shown that it is also possible to get DMPPO with high molecular weights if the catalyst which is a Cu-pyridin-complex – Py_nCuClX (X = OH, OCH₃, O_1/2) – is suspended e. g. in a mixture from xylene and pyridine. Although the catalyst is so slightly soluble in such mixtures (up to 20 vol % pyridine) that the filtrate does not give polymers with dimethyl- phenol and oxygen and the catalyst can be recovered after the polycondensation, the reaction is homogeneous. In the first step of the synthesis a part of the catalyst is dissolved by a reaction with the monomer (formation of a Cu-phenolate-pyridine-complex). This complex can catalyse the polycondensation. When the monomer concentration decreases the catalyst precipitates from the solution. The kinetics of the reaction were investigated to find out the optimal conditions of preparation. The dependence of the induction periode and the maximum reaction rate on various parameters are discussed. Experiments with a series of backmix-reactors showed that the continuous preparation of the polymer with suspended catalysts is possible. When the catalyst was fixed on acid ion exchange resins, it was not possible to prepare polymers.     

Versuche zur charakterisierung eines polystyrol-gepfropften zellstoffes

A graft copolymer of cellulose (wood-pulp) and polystyrene is made soluble by carbanilation. The dioxane-solutions are used for viscometric and UV-spectrophotometric investigations, as well as for a fractionated precipitation. The material is a genuine graft copolymer. Fractions with low limiting viscosity number carry more, but shorter branches of polystyrene than such ones with high limiting viscosity number.     

Elektrochemisch initiierte polymerisation von acrylnitril

With the aid of an electrochemical initiated reaction of pure acrylonitrile in the presence of 0,1–1% water and of small concentrations of quaternary ammonium salts, an oligomeric, yellow, in acetone soluble compound was obtained with a molecular weight of 1000–3000. The high current-yield – up to 100 g/Ah, this means that per electrontransfer up to two polymeric molecules were obtained –, the low molecular weight, the independence of molecular weight of current density, the insensitivity to oxygen, and experiments of copolymerization with styrene indicate that the oligomer is formed at the cathode by an anionic mechanism. The influence of electrolyte structure, of cathode material, of current density, of water concentration, of convection, and of temperature on the formation of the oligomer has been investigated. A proposal of the structure of the oligomeric acrylonitrile has been made.     

Die polymerisation von lactamen, 50. Die polymerisation von 8-octanlactam in gegenwart von wasser in niedrigen konzentrationen

The polymerization of 8-octanelactam in the presence of 0,15–0,95 mol-% water at 250°C was studied. The kinetic data obtained gave evidence for a different function of water at concentrations up to 0,35 mol-% and higher concentrations. With respect to the results of the end-group analysis of the polymers, which were prepared without added water or other initiators (autopolymerization), a cationic mechanism for the polymerization of 8-octanelactam in the presence of water up to 0,35 mol-% was suggested.     

Versuche zur stufenweisen epoxid/methacrylat-photopolymerisation mit diaryliodoniumsalz-photoinitiatoren

DSC-investigations confirm the experimental result that the selective photopolymerization of MMA and phenylglycidether (PGE) from a mixture of both monomers is possible with diaryliodoniumsalts/benzoinmethylether as a photoinitiator. The separation of both processes is dependent on light-intensity and on the composition of the monomer mixture. From a monomer mixture (80 weight-% MMA and 20 Weight-% PGE) it is possible to polymerize selectively MMA with light intensity I = 0.7 mJ/s cm², if the reaction is cut off immediately after the appearence of the gel effect (30 minutes). The epoxide polymerization can be completed afterwards by means of unfiltered light from a Hg-pressure lamp. The time separation of both processes will only succeed if MMA is the main part of the monomer mixture.     

Versuche zur chromatographischen racemattrennung an synthetischen asymmetrischen polymeren

Sulphochlorinated and chloromethylated polystyrene reacted with D-α-phenyl-ethylamine, D-ephedrine, D-alanine, L-alanine, L-alanine methyl ester, L-alanine benzyl ester, L-phenyl-alanine and D-α-aminophenylacetic acid yielding asymmetric polymers. These polymers were used as specific adsorbents for the chromatographic resolution of racemates. The influence of the different substituents in the asymmetric centre of the polymers and the racemates on the resolution was investigated. DL-Mandelic acid and DL-α-aminophenylacetic acid could be partially resolved, using different eluents, on the polymers, prepared from polystyrenesulphonyl chloride and optically active amino acids. Polymers prepared from polystyrenesulphonyl chloride and L-alanine esters showed stereoselective adsorption power only after the saponification of the ester groups to the free carboxyl groups. An exchange of the carboxyl group by a methyl group on the asymmetric C-atom of the polymers and also of the racemates leads to a loss of resolution activity, -respectively- separability. The replacement of the benzyl- or methyl-groups by a phenyl group showed a much greater influence on the resolution effect in the racemates than in the polymers. The presence of a (? SO₂? NH? )-bridge, in comparison to a (? CH₂-NH? )-bridge, between the matrix polymer and the optically active component increased the resolution activity. The difference in the firmness of the binding of the antipode over a hydrogen bridge linkage in the polymer was thought to be the reason for the partial resolution of the racemates.     

Versuche zur ermittlung der haftreibung zwischen betonoberflächen

With regard to the evolution of a rheological-statistical theory describing the mechanism of deformation and failure of damaged concrete using friction criterions, experiments were carried out to measure the frictional resistance to sliding of concrete surfaces. A tribometric determination of the coefficient of friction gave results in the range of 0, 15 and 0, 65, the history of the sliding surfaces being of decisive influence. An examination under the microscope demonstrated Ca(OH)₂ crystals growing out of the pore system of the matrix after a wetting-drying cycle. So the coefficient of friction increases, but repeating the sliding experiment several times the frictional resistance decreases rapidly because the breakage of the crystals is acting like a ball-bearing or as lubrication respectively. The coefficient of friction of the aggregates was measured with acid-etched concrete surfaces to be 0, 41. The frictional resistance of surfaces of pastes and mortars can be characterized by coefficients of 0, 23 and 0, 47.