In the first part of this two part thesis, interaction parameters of nitrocellulose with various solvent systems were investigated by Inverse Gas Chromatography. From these data, the solubility parameters of nitrocellulose were determined at a series of nitration levels which were used to guide the selection of suitable plasticizers for nitrocellulose films. Subsequent dynamic mechanical experiments were then used to evaluate the effectiveness of the blend formulations in broadening the glass transition dispersion of the nitrocellulose blended films; in addition, stress-strain experiments were done in order to evaluate the tensile modulus of the nitrocellulose blends. In the second part of this thesis, both dynamic mechanical thermal analysis and dielectric thermal analysis were used to evaluate the relaxation properties of thin film polysulfone coatings and the effect of substrate surface topography on these properties. Both dynamic mechanical and dielectric thermal analysis revealed that the topographical nature of the substrate influenced the linear viscoelastic properties of the thin film coatings and that the extent of this influence was dependent on the coating thickness. / Master of Science

The dielectric-dispersion, curve of cellulose nitrate may be obtained over a 1ow frequency range in h-butyl acetate. The parallel resistance method is used for capacitance measurements is a nickel cell. Comparison of the distribution curve and the dispersion curve above a distinct similarity between the two curves. A relationship of the log frequency to intrinsic viscosity has been derived and appears to be acceptable with ±10% of the values obtained from fractional precipitation. Thus the distribution curve of cellulose nitrate may be determined from the dielectric dispersion curve. / Master of Science

The investigation was begun in an attempt to obtain a cellulose nitrate, cloth, (by the direct nitration of cotton cloth) which would be suitable for use in powder bags. Such a product must have a rapid rate of combustion, a very small amount of ash, and a tensile strength which would meet Government requirements for powder bags. The results of the research conducted upon the nitration of cotton cloth indicate that a high percent of nitrogen can be obtained in a very short time. However, in most cases the action needed to produce a high nitrate is so drastic that the tensile strength of the cloth is greatly reduced. This degradation is most likely due to the hydrolytic action of the acids. / M.S.

Ph. D.

Quantitative data concerning the state of solvation of cellulose derivatives dispersed in solvent-non solvent systems is rather limited. Since such derivatives possess a high commercial importance largely because of their ability to be dispersed and regenerated from solvent-non solvent systems by manipulation of the solution phase of the system, such data are highly desirable from the purely practical viewpoint. Likewise, from the purely theoretical viewpoint, such data are desirable in the investigation of problems involving fractional precipitation techniques, studies in film and filament formation and in the elucidation or a number of similar basic phenomena of current interest. Specifically, the aim of this investigation is to study, quantitatively, the changes in solvation of a sample of cellulose nitrate in an acetone-water solvent-non solvent system as the composition of the liquid phase is varied over a range from solvent rich to solvent poor. / Master of Science

A sample of cellulose nitrate was to be fractionated into a series of fractions differing from each other with respect to the degree of polymerization. The method chosen was to be one which would give a large number of fractions, each one attaining as high a degree of homogeneity with respect to chain length as could be reached without too great refinement of procedure. The degree of polymerization of the fractions was to be determined by viscosity measurements using the Staudinger viscosity equation (109) and then using a suitable solvent, a quantitative determination of the solubility of each fraction was to be attempted. From any solubility data obtained an attempt was to be made to determine if any relationship existed between the degree of polymerization and the solubility. Solubility is dependent upon the nitrogen content of the nitrate. Therefore, the nitrogen content of each fraction was to be determined, in order to draw valid conclusions from the solubility data. / M.S.

The prime result has been the development of an experimental procedure for producing a definite dielectric effect when water is added to an acetone solution of cellulose nitrate. This effect depends not only on the purity, dryness and concentration of the cellulose nitrate, but also on the average degree of polymerization. This last dependency is shown in Figure V, and its theoretical aspects will be discussed in the next section. The discontinuity at the precipitation region is a general effect, not depending on such extreme conditions. / M.S.

La nitrocellulose (NC) est un ester nitrique de cellulose dont le taux de nitration détermine ses propriétés physiques et chimiques ainsi que ses applications industrielles. En effet, les NC ayant des taux de nitration inférieurs à 12,5% sont utilisées dans des produits courants (encres, peintures, vernis et membranes) alors que les NC présentant des taux de nitration supérieurs à 12,5% sont utilisées dans la fabrication de produits explosifs (dynamites et poudres propulsives). Il est donc nécessaire du point de vue forensique de disposer de méthodes permettant d’une part, d’identifier la présence de NC, d’autre part, de les discriminer. Les méthodes existantes sont très anciennes, lourdes, voire dangereuses, quand elles ne font pas totalement défaut. Par conséquent, il y a un réel besoin de disposer de méthodes plus modernes, moins lourdes et plus sûres, permettant d’identifier la présence de NC et de les discriminer. Dans une première partie, le rendement de dénitration des NC obtenu après hydrolyse alcaline a été optimisé à l’aide d’un plan d’expériences. Les ions nitrite et nitrate libérés après hydrolyse ont été quantifiés par électrophorèse capillaire (CE). Ensuite, une nouvelle méthode permettant de déterminer le taux de nitration des NC a été développée. Cette méthode est basée sur une relation linéaire entre le ratio molaire des concentrations en ions nitrite et nitrate libérés et le taux de nitration de la NC. Ces différentes méthodes ont été appliquées avec succès à l’analyse de NC contenues dans différentes matrices. Dans une seconde partie, les produits obtenus après dépolymérisation en milieu acide de la NC ont été étudiés dans l’objectif d’obtenir une empreinte électrophorétique présentant un intérêt forensique. Pour cela, les produits de dépolymérisation acide partielle de la NC ont été dérivés par le 8-aminopyrène-1,3,6-trisulfonate (APTS), détectés par fluorescence induite par laser, puis identifiés à l’aide d’étalons de cellodextrines, eux-mêmes dérivés par l’APTS. Les produits de dépolymérisation de la NC pourront également être analysés par une nouvelle méthode électrophorétique utilisant un électrolyte très basique avec une détection UV directe impliquant une réaction de photo-oxydation dans la fenêtre de détection. Enfin, la miniaturisation et l’automatisation de l’instrumentation de la CE a été mise à profit afin de déterminer les viscosités intrinsèques d’échantillons de NC. Après avoir déterminé les paramètres de la relation de Mark-Houwink, les masses moléculaires moyennes en poids d’échantillons de NC pourront être déterminées. / Nitrocellulose (NC) is a nitrate cellulose ester polymer whose nitrogen content determines its physical and chemical properties, and its industrial applications. Indeed, NCs with a nitrogen content less than 12.5% are widely used as raw material in daily use products (printing inks, paints, lacquers, varnishes and filter membranes), whereas highly-nitrated NCs (nitrogen content > 12.5%) are employed in the manufacturing of explosive materials (smokeless gunpowders and dynamites). Therefore, and also for regulation reasons, methods for the determination of nitrogen content in NCs are needed , and there is a strong need in developing more modern, simpler, faster, and safer methods. In a first part, the denitration yield obtained after alkaline hydrolysis of NCs was optimized by means of an experimental design. Capillary electrophoresis (CE) was used to follow the reaction through the quantitation of nitrite and nitrate ions released during hydrolysis. Then, a new method to determine the nitrogen content of NCs, based on a linear relationship between it and the molar ratio of nitrite to nitrate ions released after alkaline hydrolysis was developed. These methods were successfully applied to various explosive and non-explosive NC-containing samples. The second part aimed at studying the products obtained after partial acid depolymerization in an attempt to generate a mixture of oligosaccharides retaining information on the initial NC sample and/or the cellulose used to prepare it, which would be of forensic interest. To this end, NC fingerprinting was achieved by CE with laser induced fluorescence detection (LIF) after acid depolymerization, and derivatization with 8-aminopyrene-1,3,6-trisulfonic acid (APTS). The resulting derivatized oligomers were identified using APTS-derivatized cellodextrin standards. These depolymerization products can also be analyzed with a new CE method with a high-alkaline background electrolyte containing sodium chloride and detection was performed by mid-UV absorbance after photo-oxidation in the detection window. Finally, the advantages of CE instrumentation (miniaturization of the assay and automation) were used to determine the intrinsic viscosity of various NC samples. Thanks to the calculation of Mark Houwink parameters, the weight-average molecular weight of unknown NC samples could be determined.

No description available.

The manufacturing process for solventless extruded double base propellants involves a number of rolling and reworking stages. Throughout these processes a decrease in weight average molecular weight was observed, this was attributed to denitration. Differential scanning calorimetery data indicated that the reworking stages of extruded double base propellant manufacture were crucial to the homogenisation of the propellant mixture. To determine the homogeneity of the final extruded product, a sample was analysed across its diameter. No variations in stabiliser concentration, molecular weight, or Vickers hardness were detected. An accelerated thermal ageing trial simulating up to 8 years of ageing at 25°C was carried out to evaluate the storage characteristics. Reductions in stabiliser concentration, number average molecular weight, weight average molecular weight and polydispersity compared with un-aged samples were observed. The glass transition temperature measured using differential scanning calorimetery decreased by ~3°C. The decrease was attributed to the initial denitration reducing the energy of bond rotation and shortening the polymer chains, both factors reducing the energy required for movement. Modulus values determined from dynamic mechanical analysis temperature scanning experiments, did not detect significant variation between un-aged and aged samples. Though it was considered that variations would be likely if a more extensive ageing program was completed. In order to evaluate propellant behaviour at very high and low frequencies, time temperature superposition (TTS) and creep testing were carried out. The TTS technique superpositioned data well, allowing future investigation of high frequency propellant properties. Creep testing was considered to be an appropriate approach, though the equipment available was not optimised for such testing. This thesis is concerned with understanding how propellants are manufactured from nitrocellulose, nitroglycerine and other constituents. It is also about how the propellants decompose during long periods of time in storage, and how these changes can be measured using thermal and mechanical methods. It is about how the physical, chemical and thermal properties of the propellant composition change throughout the manufacture. This is relevant as it could be used to develop more efficient manufacturing processes, allow operators to adjust processes to tailor product properties or be used to re-design manufacturing to compensate for a different starting material. The thesis also considers how and why the properties of the product change over the course of years of storage. A specific focus on whether changes in mechanical and thermal properties occur, and if so how they can be detected.