L. L. Bircumshaw

Bio: L. L. Bircumshaw is an academic researcher from University of Birmingham. The author has contributed to research in topics: Thermal decomposition & Ammonium perchlorate. The author has an hindex of 2, co-authored 2 publications receiving 210 citations.

The Thermal Decomposition of Ammonium Perchlorate. I. Introduction, Experimental, Analysis of Gaseous Products, and Thermal Decomposition Experiments

Abstract: The thermal decomposition of ammonium perchlorate in vacuo and under small initial pressures of nitrogen, to suppress sublimation, has been investigated in the temperature ranges 220 to 280°C and 380 to 450°C. The experimental techniques for following the decomposition and subsequent analysis of the products are described and gas analysis results given. In the low -temperature range only 30% decomposition occurred though the ‘residue’ was still ammonium perchlorate. In vacuo sublimation occurred all the time and also after decomposition had ceased which indicated that the reaction was not in the vapour phase. Some of the properties of the sublimed material and the ‘residue’ were investigated; in particular, it was found that the residue which was porous in texture (the decomposition had occurred throughout the crystal) could be ‘rejuvenated’ by exposure to a solvent vapour. The crystal transformation at 240°C from orthorhombic to cubic, the addition of impurities which might be intermediate decomposition products, and the addition of some metallic oxide catalysts, were also investigated.

The Thermal Decomposition of Ammonium Perchlorate. II. The Kinetics of the Decomposition, the Effect of Particle Size, and Discussion of Results

Abstract: The kinetics of the thermal decomposition were determined over the temperature range 215 to 275 degrees C, giving mean values for the energy of activation of 27$\cdot $8 kcal for the orthorhombic form and 18$\cdot $9 kcal for the cubic form. The rate of decomposition was found to increase to a maximum with decreasing particle size and then to decrease again. An electron transfer mechanism is tentatively advanced which explains some of the observed decomposition results.

High-pressure studies of pharmaceutical compounds and energetic materials

Abstract: The effects of high pressure on pharmaceutical compounds and energetic materials can have important implications for both the properties and performance of these important classes of material. Pharmaceutical compounds are frequently subjected to pressure during processing and formulation, causing interconversion between solid forms that may affect properties such as solubility and bio-availability. Energetic materials experience extremes of both pressure and temperature under conditions of detonation and deflagration, causing changes in properties such as sensitivity to shock and chemical reactivity. This tutorial review outlines the various methods used to study these materials at high pressure, describes how pressure can be used to explore polymorphism, and provides examples of compounds that have been studied at high pressure.