Vapour pressures of aqueous solutions containing ammonia and carbon dioxide, ammonia and hydrogen sulphide or ammonia, carbon dioxide and hydrogen sulphide, have been determined at temperatures from 20‐60° C. Dissolved hydrogen sulphide is present almost completely in the form of ammonium hydrosulphide. Dissolved carbon dioxide is present in the form of carbonate, bicarbonate and carbamate of ammonium. The experimental vapour pressure data are interpreted from the viewpoint of the ionic equilibria in the solutions. The numerical values of the equilibrium constants have been derived. A method is described enabling one to calculate the vapour pressure for arbitrary compositions of the solutions. Diagrams are given for the vapour pressures of the two‐component system ammonia‐carbon dioxide, as a function of the total ammonia content and the ratio R (= total carbon dioxide/total ammonia). From these diagrams also the vapour pressures of the three‐component system ammonia‐carbon dioxide‐hydrogen sulphide can be derived approximatively.
An exploratory investigation has been carried out into a segmented polyether ester which consists of amorphous soft segments of polytertramethylene ether glycol and crystalline short chain hard segments of polyethylene terephthalate. The properties of this block copolymer have been compared with those of polyethylene terephthalate and polytetramethylene terephthalate (PTMT) and with those of the block copolymer based on PTMT. After a description of the preparation and the structure of the polyether ester, the thermal properties are discussed by means of DTA thermograms. From the stress‐strain behaviour, compared with that of the homopolymers, the elastomeric properties of the block copolymers stand out clearly. Processing characteristics are discussed on the basis of the crystallisation behaviour and the relationship between melt viscosity and shear rate. Finally, data about u.v., oxidative and hydrolytic stability are given.
ZUSAM M EN FASSU NG :Eine Methode zur Berechnung des Vernetzungsgrades von Systemen aus niedermolekularen Ausgangssubstanzen wird beschrieben. Damit ist es moglich, die Beeinflussung der Glasubergangstemperatur polymerer Netzwerke durch Vernetzungsgrad und chemische Zusammensetzung quantitativ zu bestimmen. Dies wird am Beispiel von vernetzten Polyurethanen erlautert.An Polyestermelaminharzen wird gezeigt, daO das Molekulargewicht des Polyesters und der Vernetzungsgrad des Netzwerks bei der Entwicklung von losungsmittelarmen Bindemitteln fur die Lackindustrie von g r o k r Bedeutung sind beziiglich Feststoffgehalt und Ablaufverhalten. SUMMARY:A method for calculating the crosslink density of systems originating from low molecular weight compounds is described. It is possible to determine quantitatively the influence of the crosslink density and the chemical composition on the glass transition temperature of network structures. This will be illustrated by crosslinked polyurethanes.On polyester melamine resins it will be shown that both the molecular weight of the polyester and the crosslink density of the network play an important role in the development of high solids coating systems as far as the solids content and the sagging are concerned.
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