Horst G. Langer

Thermal reactions by automated mass spectrometric thermal analysis

Abstract Combination of differential thermal analysis (DTA) with time-of-flight mass spectrometry and data storage on magnetic tape is used to study thermal decompositions. A modified Du Pont 900 DTA cell is used for reactions at atmospheric pressure with evolved gas sampling into a small time-of-flight spectrometer. For fast reactions a specially developed DTA cell is operated within the mass spectrometer and operates at high vacuum. A combination of both operational modes yields pressure dependencies of chemical decomposition. Examples studied include inorganic compounds and complexes, organometallics and organic chemicals such as fire retardants. The data are presented as intensity/temperature curves for each observed fragment, which not only yields decomposition temperatures but also—by the curve shapes—information on the mode of decomposition.

Early developments of EGA by mass spectrometry

Abstract The first attempts to combine thermoanalytical methods with Mass Spectrometry were made in the early 1960s and arose from the need to identify materials evolved during Thermal Analysis. Throughout the following years, examples from the literature demonstrated the power of this combination for a large variety of problems from different fields of chemistry. Because of the broad range of applications, today there are a multitude of ways to couple these two analytical techniques.

Thermal analysis of adsorbents in heat transfer systems

Abstract Natural zeolites and synthetic high surface area metal oxides have been investigated as adsorbents for solar-powered refrigeration systems as well as off-peak thermal storage devices. In this laboratory we have used a Du Pont 1090 thermal analyzer to determine both adsorptive capacity and adsorption isobars with water as the heat transfer agent. For one sample methanol was also investigated. Based on the shape of the isobars, performance of adsorbents as part of cooling or heating systems can be predicted. A natural zeolite was compared with two alumina and a porous carbon sample at different dew points and temperatures between ambient and 200° C. The instrumental arrangement included a constant temperature bath and a thermogravimetric analyzer modified to allow the use of water vapor saturated gases.

Metal Coordination - A Key to Oxidative Stability.

The oxidation of metal ions can be pH dependent because of kinetic effects as expressed in equation {1}

Derivatives of polyphosphoric acid partial esters

2{A^ + } + {H_2}O + 1/2{O_2} \rightleftharpoons 2{A^{2 + }} + 2O{H^ - }

Inhibiting discoloration of aqueous compositions containing hexamethylenetetramine 1,3-dichloropropene salts

(1) or might be based on a difference in stabilities of various metal complexes as indicated below {2}

Melt processable, green, ceramic precursor powder

\begin{array}{*{20}{c}} {{{\left[ {M{{\left( {O{H_2}} \right)}_6}} \right]}^{2 + }}\;is\;more\;stable\;than{{\left[ {M{{\left( {O{H_2}} \right)}_6}} \right]}^{3 + }}} \\ {{{\left[ {M{{\left( {OH} \right)}_6}} \right]}^{3 - }}\;is\;more\;stable\;than\;{{\left[ {M{{\left( {OH} \right)}_6}} \right]}^{4 - }}} \end{array}