Conventional methods of imparting toughness to ordinarily brittle thermosetting resins involve the incorporation of a second, discreet phase. Traditionally, this phase has been either a functionalized butadiene-acrylonitrile based elastomer or an unreactive thermoplastic. This dissertation describes the preparation, characterization, and evaluation of new functionalized polysiloxane elastomer and thermoplastic modifiers and their morphological implications to the toughening and physical behavior of, principally, epoxy thermosetting systems. Secondary amine-terminated poly(dimethyl-co-diphenyl siloxane) oligomers were found to be comparable tougheners to acrylonitrile-butadiene rubbers for a bisphenol-A based epoxy resin. The system that imparted the highest toughness was comprised of statistically placed 40% diphenyl and 60% dimethylsiloxane units with Mn̅ of 5000 g/mole loaded at 15% w/w. This composition resulted in a discreet second phase consisting of l μm spherical particles which were evenly dispersed throughout the cured epoxy matrix. Amine-terminated poly(arylene ether ketone) and poly(arylene ether sulfone) thermoplastics were reacted into an EPON 828/4,4'·DDS system. However, the polyketones proved to be ineffective toughening agents due to an incompatibility resulting in macroscopic phase separation. In contrast, the functionalized polysulfones were shown to be effective toughening agents, with the resultant morphology primarily a function of percent incorporation. At ~15% w/w, the polysulfone separated as l-2μm discreet particles while a 30% loading level resulted in a bicontinuous “honeycomb” morphology. The amine endgroups were shown to be necessary in controlling morphology and maximizing toughness. The polysulfone oligomers were also incorporated into a graphite fiber reinforced epoxy composite. Although improved mechanical properties were achieved, the toughness values were not as high as predicted by the neat resin evaluation. The morphology was less definable due to the complex nature and dimensions of the carbon fiber/matrix interactions. Finally, melt processing experiments indicated that amine-terminated polysulfones may act as effective processing aids for brittle bismaleimide systems, by reacting with the BMI, possibly via a Michael addition. This results in a chain extension and higher molecular weight without premature gelation occurring. / Ph. D.

Chemical and physical changes occur during the processing of toughened thermosetting resins. A number of properties are related to the type and sequence of these changes. There is a need for the development of in-situ real-time sensors to follow these changes. Once these sensors are developed, they can be used to preferentially select networks and/or morphologies by feedback-controlled "intelligent" processing. A practical, durable, inexpensive Fourier Transform NearInfrared (FTNIR) fiber optic sensor was developed and the cure of a model toughened cyanate as well as a commercial paste adhesive was followed with this sensor In the near-infrared. The design was suitable for many applications. A mold was designed to incorporate the fiber sensor for composite applications. The growth of the normalized triazine (crosslink) peak appeared to follow second order kinetics. The normalized peak reflected chemical as well as physical changes. Analysis of the individual peaks showed significant physical effects. Conversion based on triazine concentration did not follow second order kinetics. / Ph. D.

A wax distribution quantification procedure using digital image analysis and fluorescence microscopy techniques was developed. The procedure was evaluated by investigating the effect that variable application rates have on wax distribution. The effect of emulsion type and application on |B strength, thickness swell, water absorption, and linear expansion of flakeboard panels were also investigated. Tests revealed that increasing the wax emulsion flow rate and application pressure had a significant affect on wax coverage. A lower amount of flake surface area was covered when the flow rate and air pressure was increased. It was also found that the presence of resin on the flakes affected wax coverage. Resin presence generally increased the wax coverage variability. The application flow rate and pressure also seemed to affect the interaction present between the resin and wax spots. The fractional coverage area of spot size classes was also significantly affected by the emulsion's application parameters. Increasing the flow rate and air pressure was shown to create more variable wax spot distributions. The presence of resin spots on the flakes was also shown to significantly affect the spot size distribution. Changes in the emulsion flow rate and application air pressure also appeared to have a significant affect on wax spot distribution. The type of wax emulsion used, as well as increased application flow rate and pressure, was shown to significantly affect both 2 hour and 24 hour water absorption (by weight). It was found that using a soap based emulsion improved the water absorption characteristics, and that increasing the emulsion's application flow rate and air pressure adversely affected the water absorption. Differences in IB strength and 24 hour thickness swell were also seen between the panels made using increased flow rate and pressure and the panels produced with standard parameters. However, due to possible influence of press malfunctions on the boards performance, conclusions about the effect of increased parameters can not be clearly drawn. No significant difference in linear expansion was seen for any of the samples tested. / Master of Science

The purpose of this research was to determine whether all-purpose flour could be partially replaced with locust bean gum (LBG) and guar gum, and produce an acceptable bread product. A pilot study determined that up to 4% gum replacement for flour was feasible. All bread treatments were evaluated objectively by standing height, texture, color, and cell size. Moisture determinations were obtained for each bread variation. Sensory quality was examined by consumer testing. The amount of heat required to break the hydrogen bonds in amylopectin, indicative of bread staling, was measured by differential scanning calorimetry (DSC) for all bread treatments. Two percent LBG replacement significantly increased standing height. Firmness of bread increased with an increase in gum; the 4% guar bread was significantly firmer. Crumb color was not significantly different for any of the five bread treatments. Crust color, however, was significantly lighter for the control in comparison to the 2 and 4% guar, and 4% LBG breads. Two percent guar produced a more even cell size distribution throughout the bread crumb. For all 5 bread formulations moistures were not significantly different. Sensory evaluation determined a significant difference between the control and 4% LBG. The 4% LBG bread was preferred, although not significantly. Both gums were found to retard bread staling and 2% LBG was the most effective in lengthening the shelf life of the bread product. Objective and sensory evaluation indicated both gums produced acceptable bread products for consumer consumption and possible use in further research. / Master of Science

The objective of this study was to develop a two-dimensional computer model for the simulation of the resin transfer molding/resin film infusion processing of advanced composite materials. This computer simulation model is designed to provide aircraft structure and tool designers with a method of predicting the infiltration and curing behavior of a composite material component. For a given specified cure cycle, the computer model can be used to calculate the resin infiltration, resin viscosity, resin advancement, heat transfer within the component/tool assembly during processing and preform compaction. Formulations of the resin flow problem are given using the finite element/control volume technique based on Darcy's Law of flow through porous media. This technique allows for the efficient numerical calculation of the advancing resin front within the preform materials. The heat transfer in the fabric preform and tooling is analyzed using a transient finite element method which included the effects of convection on the tooling surfaces. Compaction behavior of the tooling assembly is analyzed using a simplified isotropic form of the plane elasticity equations. All of these solutions were coupled together in a quasisteady state non-linear fashion inside the computer code. / Master of Science

Tall oil is a mixture of rosin acids, fatty acids, and non-acids resulting from acidification of the soaps separating out from the kraft pulp process evaporator liquor. The present uses of tall oil center chiefly around its fatty acid content, but are limited for some purposes because of the rosin content. Separation of these constituents makes each available as such. The rosin, as crystalline abietic acid, has specific possibilities as a raw material. Rosin and fatty acids are separated chiefly by distillation, although chemical means and extraction have been proposed to overcome such objections as corrosion and losses as pitch, incurred in distillation. Chlorination is used as a step in the purification of tall oil, or to produce a sticky chlorinated oil, but no separation based on the use of chlorine appears to have been proposed. It was proposed in this investigation to chlorinate the fatty acid double bonds in hopes that the properties of this product would be such as to permit of a separation. The effects of solvent, light, heat, and catalysts were studied to determine the optimum conditions for such a reaction, and the effect of chlorination upon the rosin and fatty acids, respectively, under specific conditions was determined, It was found that the use of CCl₄ solvent and ultraviolet light accelerate chlorine consumption and promote the addition of chlorine, but do not entirely stifle the substitution reaction. Rosin and fatty acid double bonds are attacked to about an equal extent under these conditions. The chlorinated oil is entirely soluble in most common solvents at room temperature. Petroleum ether insolubles increase slightly over the amount obtained from untreated oil. It is recommended that the range of chlorination conditions be extended to a more complete study of possible results, and that other chemical attacks be investigated. / Master of Science

"Resins" is a class of compounds believed to play an important role in the conversion processes of coal and coal-related materials into oils. Methods currently used to isolate this fraction, generally lack reproducibility and yield impure and strongly overlapping fractions which do not reflect the actual group-type distribution in the liquid fuel. A separation method based on liquid column chromatography was developed, which divides liquid fuels into eight distinct and minimally overlapping chemical classes: five non-polar (saturated, mono-, di-, tri-, and polynuclear aromatics), one intermediate polar (resins) and two polar (asphaltenes and asphaltols) fractions. Chemical characterization of "resins fractions," derived from two alternative fuels (coal-derived liquid and sugarcane bagasse), was achieved by first subjecting them to acid-base-neutral separation, followed by analysis of each subfraction by GC/MS. Identification of the eluted components was carried out utilizing a library search system, by comparing retention times (indices) of 150 model compounds believed to exist in liquid fuels, on two fused silica capillary columns (Carbowax 20 M and SE-54), and by mass spectral interpretation. GC/MS results indicate that "resins" are mainly composed of weakly acidic (phenols, indanols, naphthols), mildly basic (benzoquinolines, chloroanilines, etc.), neutral-nitrogen (indoles and carbazoles), and oxygen (carbonyl) compounds, and are free of hydrocarbons. / Ph. D.

Large Area Maskless Photopolymerization (LAMP) is a technology being developed to fabricate integrally-cored ceramic molds for the investment casting of turbine airfoils. In LAMP, ultraviolet (UV) light in the form of bitmap images is projected from a spatial light modulator (SLM) onto a photocurable ceramic material system (PCMS). Exposed and unexposed regions are determined through black and white portions of the bitmaps, respectively. UV light induces photopolymerization and the formation of an insoluble solidified network. Three-dimensional structures are built layer-by-layer through sequential application and curing of PCMS layers of 100 micron thickness. To date, ceramic molds fabricated using LAMP have been successfully implemented in investment casting of single-crystal turbine airfoils without internal cooling schemes. Two particularly important challenges for the fabrication of airfoil molds with internal cooling passages are: (a) fabrication of unsupported structures in the mold geometry and; (b) mitigation of internal stresses that arise during layer-by-layer build-up due to volumetric shrinkage during photopolymerization. Unsupported geometries arise in nearly every cored airfoil mold and often in a location where support structures cannot be easily removed after fabrication. Internal stresses generated by volumetric shrinkage can lead to cracking during binder burnout (BBO), sintering and casting. This thesis aims to simultaneously address these challenges through the investigation of grayscale exposure to control the degree of monomer conversion during photopolymerization of single and multiple layers. The effective intensity of the UV light incident on the monomer system can be reduced by selectively turning off pixels within the nominally "white" or "on" regions of the projected bitmaps, effectively producing an exposure with a lower light intensity. In an effort to reduce internal stresses in the mold, the grayscale exposure can be tuned to create regions of uncured or partially cured monomer within the mold geometry to reduce the connectivity between cured regions and thus reduce the net effect of volumetric shrinkage. Grayscale exposure can also be used to generate support structures with a low degree of polymerization to create a gel state beneath and surrounding the unsupported segments of the mold, which can be washed away after completion of mold fabrication. In order to successfully utilize grayscale techniques in LAMP, the cure depth must be predicted. This is accomplished through cure depth measurements at different exposure times to develop a "working curve." In addition, the degree of monomer conversion and its relation to cure depths resulting from grayscale exposure must be understood. Measurements of the degree of conversion are obtained through Fourier Transform Infrared spectroscopy (FTIR). Empirical models are developed and compared to theoretical predictions. Also, the scattering length pixelation model is introduced as a technique to predict the light intensity distribution within the PCMS for exposure patterns at multiple length scales. Results from these grayscale investigations are then applied to LAMP and the effectiveness of grayscale to fabricate unsupported geometries and internal stresses from volumetric shrinkage is discussed.

This research project is partnership project involving industrial, university and government collaborators. The overall objective is to develop and enhance tools for use in Resin Transfer Moulding (RTM) design technology in order to re-design existing metallic parts using composite materials. / The specific objective of this work is to present preliminary research findings of the development of an optimized design of a leading edge slat (horizontal stabilizer component) from the Bell Model 407 Helicopter. The results presented here focus on the static stress analysis and the structure design aspects. The findings will serve as a basis for future design optimization as well as further developments in the use of RTM technology in re-designing metallic aeronautic components and can be considered to be "semi-optimized". / This research is based on extensive finite element analysis (FEA) of several composite material configurations, with a comparison made with the original metallic design. Different key criteria of the part design such as ply lay-up, bracket geometry, angle and configuration are tested using FEA technology with the objective of selecting the design which is minimizing stress concentrations. The influence of the modification of model-related parameters was also studied. / Preliminary comparative studies show that the slat configuration with half brackets opened towards the inside with an angle of 70 degrees (angle between the top of the airfoil and the side of the bracket) is the best option according to minimum stress concentration and structural flexibility. This choice is confirmed by other factors such as material savings and ease of processing.

Capes / Com o desenvolvimento das tecnologias de impressão tridimensionais (3D) para prototipagem rápida, novos materiais estão sendo constantemente pesquisados, porém, nem todos possuem as características necessárias para serem utilizados para esta finalidade. O custo dos materiais comumente utilizados e suas limitações de aplicação e reutilização são aspectos que devem ser levados em conta, e envolvem a busca por materiais de baixo custo, com adequadas características termomecânicas como também de manufatura, reciclagem, biodegradabilidade e que sejam provenientes de fontes renováveis. Empiricamente, a história da farmácia e da medicina é conhecida por utilizar plantas medicinais devido a suas propriedades bioativas, recentemente a comprovação científica da utilização das substâncias resultantes de seu metabolismo secundário justifica esta afirmação. Dentro deste contexto, o objetivo geral desta tese foi avaliar a bioatividade das resinas vegetais de Stirax benzoin, Commiphora myrrha e Boswellia papyrifera contra os micro-organismos Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, e Candida albicans através da metodologia de difusão em ágar, e também verificar sua possibilidade de aplicações como materiais de impressão 3D através da avaliação de suas propriedades térmicas e físico-mecânicas. Os filamentos foram confeccionados via Hot Melt Extrusion (HME) sendo posteriormente impressos via Fused Deposition Modeling (FDM). Os materiais obtidos foram caracterizados por espectroscopia no ultravioleta visível (UV-vis), infravermelho com transformada de Fourier (FTIR), difração por raios X (DRX) e calorimetria exploratória diferencial (DSC), adicionalmente testes de resistência mecânica à tração e à compressão também foram realizados. Como resultado os materiais inibiram o crescimento dos organismos patógenos em estudo como também apresentaram características adequadas de extrusão e impressão 3D utilizando a técnica de modelagem por deposição fundida. / With the development of three-dimensional (3D) printing technologies for rapid prototyping, new materials are constantly being researched, but not all of them have the necessary characteristics to be used for this purpose. The cost of the commonly used materials and their limitations of application and reuse are aspects that must be taken into account, and involve the search for low cost materials with adequate thermo-mechanical characteristics as well as manufacturing, recycling, biodegradability and that come from sources renewable sources. Empirically, the history of pharmacy and medicine is known to use medicinal plants due to its bioactive properties, recently the scientific evidence of the use of the substances resulting from its secondary metabolism justifies this statement. Withing this context, the general objective of this thesis was to evaluate the bioactivity of the plant resins of Stirax benzoin, Commiphora myrrha and Boswellia papyrifera against the microorganisms Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans through diffusion methodology In agar, and also verify its possibility of application as 3D printing materials through the evaluation of its thermal and physical-mechanical properties. The filaments were made by Hot Melt Extrusion (HME) and later printed by Fused Deposition Modeling (FDM). The obtained materials were characterized by visible ultraviolet (UV-vis), Fourier transform infrared spectroscopy (FTIR), X rays diffraction (DRX) and differential scanning calorimetry) in addition mechanical resistance to traction and compression tests were also performed. As a result, the materials inhibited the growth of the pathogens organisms under study, as well as exhibited suitable characteristics of extrusion and 3D printing using the technique Fused Deposition Modeling.