All ETDs from UAB

Advisory Committee Chair

Sergey Vyazovkin

Advisory Committee Members

Derrick R Dean

Tracy P Hamilton

Andrei Stanishevsky

Charles L Watkins

Document Type

Dissertation

Date of Award

2010

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

This research project characterizes ammonium nitrate (AN) and ammonium perchlorate (AP) to assist in the parameter optimization of ammonium-salt propellants. Throughout these studies, the effective activation energies for thermal events are identified through the application of the Advanced Isoconversional Method. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), High Pressure DSC (HP-DSC), Fourier Transform Infrared Spectroscopy (FTIR), TGA-FTIR evolved gas analysis, density functional calculations, and microscopy techniques were employed to evaluate the systems. The first article studies the thermal decomposition properties of ammonium perchlorate as a function of sample condition. It was discovered that sublimation and decomposition are dependent on particle size, the density resulting from compression, and the pressured exerted by the sheath gas. The onset of AP's thermal decomposition appears to be similar for all samples, however, the later stages exhibit a significant change in the effective activation energy depending on the sample preparation. The second and third articles are primarily focused on a novel approach to influence the thermal behavior of AN through the use of polar polymer matrices. Polyvinylpyrrolidone (PVP) and polyacrylamide (PAM) were utilized as hosts for AN. It was discovered that both PAM and PVP forms an amorphous glass with AN when the respective anion and cation are spatially separated from each other. This separation is achieved though an ion-dipole interaction with the amide located in the functional group of the host polymers. Glass formation was confirmed by the absence of AN's solid-solid phase transitions in the DSC, polarized optical microscopy, and quantum mechanical calculations. It was discovered that PVP and PAM are able to effectively separate the respective ions until the glass transition temperature (Tg) of PVP and the early stages of polymer degradation for PAM at which point a highly exothermic reaction takes place.

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