Zusammenhang zwischen den Charakteristiken der dispersen und der kohärenten Phase bei einem Verfahren zur Radikalcopolymerisation von Styrol und Polybutadienkautschuk

Block-suspension copolymerization of a solution of polybutadiene rubber in styrene occurred in the presence of different concentrations and ratios of components in combined initiator systems AIBN-BPO-TDM. The molecular parameters (M?_n, M?_w, M?_z) and molecular mass distribution of the continuous plastic phase were determined by GPC. The GPC data were treated by electronic computer. With computer techniques, employing data of a semiautomatic apparatus for measuring and counting of the dispersed species the parameters of the disperse elastomer phase were calculated. A correlation between the parameters of dispersion and continuous phases, the conditions of the copolymerization process and physical-mechanical properties of the copolymers was established.     

Möglichkeiten zum Nachweis einer Hitzeeinwirkung auf Rapssaat im Zusammenhang mit Glucosinolat-Bestimmungsmethoden

Ways to Detect Heat Exposure of Rapeseed in Relation to Glucosinolate Determination In wet summers rapeseed lots may have to be dried during harvesting by the action of hot air prior to storage in a silo. In the laboratory, samples for analysis must often be dried because rapeseed with a higher degree of humidity can be difficult to grind or mill. In some laboratory protocols, the ise of microwave ovens is recommended. When rapeseed is heated, components can be chemically transformed in such a way that they are no longer accessible to analysis methods designed for the original parent compound. This is also the case with glucosinolates and some of their analysis methods, particularly when microwave drying of samples is used. Discrepancies in glucosinolate results, particularly between the result of a sulfur or sulfate determination on the one hand, and GLC or HPLC of desulfoglucosinolates on the other hand, may have been caused by excessive drying if batches and by the fact that the GLC or HPLC methods in use do not determine decomposed glucosinolates. The known thermal decomposition of glucosinolates is particularly evident in 00-rapeseed because of the increased lability of 4-hydroxyglucobrassicin — a prominent 00-rapeseed glucosinolate. It was therefore of interest to find independent methods to detect heat exposure in rapeseed. A number of possibilities are discussed and investigations based on the pattern of chlorophyll degradation products are described. An analysis of the degree of formation of the pyropheophytins a and b permits to decide whether or not a sample of rapeseed had been heated excessively or dried by microwave absorption.     

Zum Zusammenhang zwischen idealen und realen Gemischen bei der Destillation

The Relation Between the Distillation of Ideal and Real Mixtures A complete theory exists for the distillation of ideal mixtures, i.e., mixtures with constant relative volatilities. This theory allows one to answer any questions that arise during the distillation of multicomponent systems using simple algebraic equations. The concepts of ideal mixtures can, at least quantitatively, be used for the distillation of real multicomponent systems, no matter how complex, as shown in this work. The understanding of the basic principles for the distillation of these mixtures is, therefore, remarkably simplified.     

Staugrenze bei der Begasung mit Lochböden

In gas‐liquid contacting with perforated plates a certain gas velocity exists, above which the weeping rate will decrease noticeably. This loading point was identified as the transition between the bubbling and jetting regime, based on a physical model derived in previous studies. The same criterion is valid for gas‐solid fluidized beds.     

Konzentrationsänderung der chemischen Querbindungen im Gel und des Molekulargewichtes der löslichen Fraktionen beim Entschwefeln von Vulkanisaten mit Raney-Nickel

An experimental study of desulfurization of rubber networks with Raney nickel at different conditions has been carried out. The change of the concentration of the crosslinks in the gel was investigated. The molecular weight of the soluble fractions was determined. On the basis of the obtained results the conclusion was drawn, that the desulfurization of the rubber networks with Raney nickel takes place in the bulk of the rubber network without degradation of rubber molecules. Experimentally determined values of the molecular weight of the sol-rubbers are in agreement with the values obtained theoretically on the basis of the sol-gel theory.