Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xiv, 137 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 106-109).

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The dissolution profile of orally delivered drugs can be controlled through the use of osmotically controlled drug delivery devices. The most commonly used device is the osmotic tablet, which is essentially a tablet core that is coated with a rate-limiting semipermeable membrane. The feasibility of applying a coating onto a tablet using dense gas techniques was studied. Two different coating materials, polymethymethacrylate (PMMA, Mw = 120,000 g/mol) and cellulose acetate (CA, 39.8 wt% acetyl content) were applied onto an 8 mm osmotic tablet core using the Gas Anti-solvent (GAS) process. For PMMA, the pressurisation rate, coating temperature and volumetric expansion of up to 250% had minimal effect on the coating quality. The concentration, solvent type and the use of polyethylene glycol (Mw = 200 g/mol) had a more pronounced effect on the coating. The coating process was optimised to apply a smooth and uniform coating with a 50 ??m thickness. For CA, the pressurisation rate and the coating temperature had little effect on the coating that was applied. The process was more sensitive to a change in the concentration of the solution and the volumetric expansion that was used. It was found that the concentration could not be increased too much without affecting the coating quality. A CA coating was applied onto a PMMA-coated tablet using the optimised conditions. The thickness in the tablet coating increased by 10 ??m. Dissolution tests of the uncoated and coated tablets were carried out. The CA coatings were found to be insufficient in limiting the rate of water entering the tablet and performed similarly to an uncoated tablet core. The PMMA coatings were found to limit the rate of delivery of the model drug. However, variations in the PMMA coatings resulted in an inconsistent delivery profile across batches. The tablets coated with both PMMA and CA had a delivery rate in between that of uncoated and PMMA-coated tablets, indicating that the application of the second coating had compromised the initial PMMA coating.

Thesis (M.S.)--Rutgers University, 2007. / "Graduate Program in Ceramic and Materials Science and Engineering." Includes bibliographical references (p. 49-50).

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Public Health." Includes bibliographical references.

Thesis (M.S.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

Thesis (Ph. D.)--Lehigh University, 2006. / Includes bibliographical references and vita.

This research aims to contribute to the safe methodology for additive manufacturing (AM) of energetic materials. Coating formulation processes were investigated to find a suitable method that may enable selective laser sintering (SLS) as the safe method for fabrication of high explosive (HE) compositions. For safety and convenience reasons, the concept demonstration was conducted using inert explosive simulants with properties quasi-similar to the real HE. Coating processes for simulant RDX-based microparticles by means of PCL and 3,4,5- trimethoxybenzaldehyde (as TNT simulant) are reported. These processes were evaluated for uniformity of coating the HE inert simulant particles with binder materials to facilitate the SLS as the adequate binding and fabrication method. The critical constraints being the coating effectiveness required, spherical particle morphology, micron size range (>20 μm) and a good powder deposition and flow, and performance under SLS to make the method applicable for HEs. Of the coating processes investigated, suspension system and single emulsion methods gave required particle near spherical morphology, size and uniform coating. The suspension process appears to be suitable for the SLS of HE mocks and potential formulation methods for active HE composites. The density was estimated to be comparable with the current HE compositions and plastic bonded explosives (PBXs) such as C4 and PE4, produced from traditional methods. The formulation method developed and the understanding of the science behind the processes paves the way toward safe SLS of the active HE compositions and may open avenues for further research and development of munitions of the future. / Dissertation (MSc (Applied Science:Chemical Technology))--University of Pretoria, 2019. / Chemical Engineering / MSc (Applied Science:Chemical Technology) / Unrestricted

Novel poly(imide siloxane) copolymers were prepared and developed as high performance fiber coatings. These copolymers were synthesized and characterized extensively as a function of chemical composition. The polyimides were then utilized to coat prototype fibers which were subsequently evaluated regarding thermal stability, thermal behavior, and hydrophobicity. The polymer series included poly(imide siloxane)s which were prepared in two steps, the first involving the generation of soluble poly(amic acid} intermediates which were then cyclodehydrated by heating in a coamide solution, at temperatures ranging from 140 to 170°C, resulting in soluble polymer which exhibited excellent thermal and mechanical properties. Because of the different nature of the imide and siloxane, a two phase microstructure developed at relatively low block molecular weight. X-ray photoelectron spectroscopy (XPS) and contact angle measurements indicated that the surface of the copolymer films was dominated by siloxane. A series of coating solutions was prepared, controlling the solution concentration, solvent, and viscosity. Polybenzimidazole and Kevlar aramid multifilament yarns were immersion coated, dried, and evaluated. Due to the surface segregation of siloxane, these coated fibers advantageously displayed lower moisture sorption as measured in three environments of different humidities. Thus, the coating acted as a hydrophobic barrier. These coated fibers were also evaluated by thermogravimetric analysis (TGA) which displayed that the dynamic thermo-oxidative stability was improved. Finally, thermal expansion coefficients were measured in order to determine coating integrity or matrix/resin integrity under thermal stress. / M.S.

Direct measurements of surface temperatures produced during fretting contact are an unknown area in the discipline of tribology; in addition, the possible effects of such temperatures on the behavior of protective anti-fretting coatings (e.g., polymeric) have never been investigated. An oscillating contact device was designed and built to study fretting contact behavior in tribological processes. The contact geometry consisted of a stationary spherical test specimen loaded against a vibrating sapphire disk driven by an electromagnetic shaker. Surface temperatures generated by frictional heating were measured during fretting contact using an infrared microscope. A photo/video technique was developed to view the fretting contact interface during an experiment and to measure the size and distribution of real area(s) of contact. The effects of size and distribution of the areas on the experimental surface temperatures for polymer-coated steel spheres-on- sapphire were investigated. Archard's theoretical model was also modified to account for multiple contact areas, and the calculated surface temperatures were compared to the experimental results. Polymeric coatings - including polystyrene (PS), polymethylmethacrylate (PMMA), polysulfone (PSO), polyvinylchloride (PVC), and polyvinylidenechloride (PVDC) were studied at a given load (20 N), frequency (150 Hz), amplitude (100 JLm), and film thickness (55 p.m). The surface temperatures generated were generally low and below the glass transition temperatures of the rigid polymers studied. The magnitude of the surface temperatures was found to be particularly dependent on the size and distribution of real area(s) of contact. The most extensive studies were performed using polystyrene coatings. Effects of load, frequency, amplitude, and film thickness on surface temperature rise and the size and distributions of real area of contact were examined. In addition, uncoated steel specimens were studied under various loads and fretting amplitudes. The observed formation of iron oxide at low surface temperature (60°C) tribologica1 experiments was explained in terms of exoelectron emission. There were considerable differences observed in the behavior of polymeric coatings under various fretting conditions. The fretting behavior of the coatings was explained in terms of mechanical and thermo-elastic effects. Thermo-elastic predictions of size distributions of real contact areas (patches) showed good agreement with the observed photo/video studies. A mechanism was proposed for tribological behavior and fretting protection of polystyrene coatings. / Ph. D.