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The physical and chemical properties of orally inhaled powders in capsule-based dry powder inhalers (DPI) are crucial in maintaining a stable and functioning product during its shelf-life. The process history of a material has been known to directly influence formulation structure, performance, thermodynamic stability and shelf-life of a DPI product. It is also well-known that size-reduction processes, such as air-jet micronisation, activate an otherwise stable crystalline form of a material due to the high energy attrition the materials are subjected to. Process-induced structural defects upon particle comminution, which appear almost exclusively at the surface of a processed material, inevitably lead to an unstable, activated state. This energetic state will undergo mechanical relaxation post-micronisation. Relaxation is a thermodynamically driven and a time-dependant process where a material is driven to revert to a more stable form. Certain materials, including micronised lactose monohydrate, may succumb to degradation in the presence of a partial water vapour pressure, and can be rendered unusable during this period of relaxation. It is, therefore, crucial to understand the underlying processes dictating relaxation to achieve better control and a quality-led design of an orally inhaled drug product. This study focused on characterising the inherent disorder associated with micronised α-lactose monohydrate, and identifying methods and mechanisms by which material stability can be restored. An array of physical and chemical characterisation techniques were used to assess the material properties of micronised lactose before and upon conditioning using well-defined conditions of relative humidity and liquefied propellants. These studies indicated that air-jet micronisation can introduce profound changes to the distribution of crystal-bound water within micronised lactose monohydrate. The laagering effects of freshly micronised lactose monohydrate under ambient conditions were also investigated, and suggested an apparent but insignificant amount of dissipation of the energy associated with the mechanical activation process. Studies using controlled environmental conditioning to stabilise micronised lactose monohydrate showed no significant changes in the material's physical properties. However, results showed an unprecedented thermal behaviour in the material. Drastic changes in the distribution of freely-bound water and in the material's lattice were observed. In another study, a novel technique assessing the degradation of freshly micronised and conditioned lactose was undertaken over a six-month period under stressed stability conditions. A volatile degradation molecule was suppressed upon conditioning, suggesting a more stable form of micronised lactose monohydrate may have formed. A study was also undertaken to understand the effect of intense ball milling for size-reduction of primary crystals of lactose monohydrate. With a lower energy input during comminution, ball milling did not induce similar thermal changes observed for micronised lactose whilst its physical character was comparable. In establishing that freely available water under ambient conditions is a major issue for controlling metastable pharmaceutical powders, investigations into the stability and conditioning of commercially available capsule-based DPI products was commenced using water activity measurements. A novel method developed to assess the influence of water activity and equilibrium relative humidity in the headspace surrounding hermetically sealed capsule-based products, suggested that pre-equilibration appears to play a defining role in the successful shelf-life of capsule-based inhaler products. Finally, a study on the stability of a tiotropium formulation was investigated at elevated temperatures across a wide range of relative humidities with time. Results indicated that a relationship between the formulation and the material properties of the capsule may readily degrade the formulation and severely affect shelf-life and product performance.

Growing environmental concerns associated with the production and disposal of traditional plastics, the depletion of non-renewable fossil resources, as well as pollution of landfills and the oceans have motivated researchers to pursue alternatives to petroleum-based materials. To this end, this research aims to develop environmentally friendly alternatives to petroleum-based plastics, thereby reducing the dependence on non-renewable resources. Namely, we report on the fabrication and characterization of polymer blends consisting of copolymers derived from soybean oil (as a minor phase) and matrix made from commercially available polymers: Polystyrene (PS) and Poly(lactic acid) (PLA). The copolymers employed in this work were obtained by free radical emulsion copolymerization of high oleic soybean monomer (HOSBM) with Myrcene and Styrene (ST). First, the copolymer composed of HOSBM and Myrcene (90:10 wt/wt) was blended with PS in the range of 5-20% to harness the favorable properties of PS while improving the material’s ductility and toughness. The blends depicted phase-separated morphology and were partially miscible. However, improvement in toughness and ductility was not achieved, and when compared to mechanical models, the experimental moduli fell below the lower-bound moduli predicted by the Takayanagi model. To improve the interfacial stress transfer, a chemical modification was made to the copolymer composition, thereby replacing Myrcene with an equal amount of Styrene (ST) to obtain HOSBM-ST (90:10 wt/wt). The PS/HOSBM-ST (90-10) blends also had a phase-separated microstructure with partial miscibility. The employment of HOSBM-ST (90-10) in the blends at 5-20% improved the interfacial stress transfer, and the experimental values of the moduli were close to the upper bound values predicted by the Takayanagi model. The optimal HOSBM-ST (90-10) loading where the relatively high modulus and strength (2302, 37 MPa) were complimented with improved ductility and toughness (0.027 mm/mm, 0.660 MJ/m3) , was 10%. The improvement of the mechanical properties compared to the blends containing HOSBM-Myrcene (90-10) came at the cost of reducing the bioderived content of the copolymer. Thus, the reduction of Styrene content in the HOSBM-based copolymer from 10 wt% to 5 wt% was explored and the effects on the properties of the blends were investigated. The phase-separated and partially miscible PS/HOSBM-ST (95-5) blends showed similar thermal and mechanical behavior to those containing the same amount of HOBSM-ST (90-10). However, the blend consisting of 5% HOBSM-ST (95-5) demonstrated the highest modulus and strength (2503, 43 MPa) as well as ductility and toughness (0.031 mm/mm, 0.920 MJ/m3) among all PS-based blends studied here. The blending of HOSBM-Myrcene (90-10) with PLA was also investigated with the aim of obtaining fully bioderived polymer blends with high modulus/strength and improved toughness/ductility compared to the brittle PLA. The copolymer was added at 5-10% loadings to harness the high modulus and strength of PLA. The blended materials were partially miscible, and had high modulus and strength (2675, 54 MPa for 5% HOSBM-Myrcene (90-10) addition) as well as improved ductility and toughness (0.120 mm/mm, 5.53 MJ/m3 for 5% HOSBM-Myrcene (90-10) addition). The water absorption and wettability of PLA were also significantly decreased with the addition of the hydrophobic plant oil-based copolymer.

The common goal of researchers and practitioners in conservation of monuments is to stretch as much as possible the lifespan of built heritage. However, despite this common target, work carried out in the laboratory and on the field are all too often disconnected. In the context of stone consolidation, for example, practitioners are often skeptical about treatment recommendations emerging from laboratory studies, due to the often-questionable representability of the tests employed. To improve this situation, we describe the development of a research approach that would allow researchers to more pragmatically assist conservators in their decision-making, while also achieving a broader scientific significance. In particular, we discuss the application of this strategy for conservation treatments applied to swiss monuments built out of molasse sandstones. These stones contain swelling clays, which makes them particularly susceptible to weathering. The difficulty in preserving such substrates is exacerbated by the lack of effective consolidation treatments, since common ethyl silicate-based products (TEOS) tend to lose their effectiveness shortly after application. A possible solution lies in using swelling inhibitors that have been shown in laboratory to potentially extend the durability of consolidation treatments. However, it is still not clear in which specific conditions these treatments would be worth applying. We used a Design of Experiment (DOE) to analyze the simultaneous effects of varying environmental conditions and treatments procedures on the effectiveness of TEOS-based consolidation and swelling inhibition treatments for swiss molasses. We showed that the application of ethyl silicates at high relative humidity and low temperature greatly decreases their curing time, without compromising their effectiveness. We also demonstrated that swelling inhibitors effectively improve the durability of ethyl silicate consolidation treatments. In terms of accelerated testing, we developed an automated machine for simulating “critical events” (i.e., a specific combination of damaging conditions leading to the most damage) in the laboratory. We attempted to identify critical cycles at the cathedral of Lausanne, by characterizing wetting and drying conditions at the façade depending on orientation, and monitoring the materials response to the weathering conditions through measurements of the water movement throughout the depth of the stone. At orientations typically presenting severe damage, a critical distribution of water can be observed at a depth of 6 cm during the winter months, suggesting that freezing might play a crucial role in the initiation of contour scaling. This water profile is not created by individual critical events, but results from an overall cumulation of events. Once established, it remains probable that degradation is caused by specific events, but these still remain to be clearly defined and reproduced in laboratory. Ongoing laboratory experiments under simulated on-site conditions are presented, which aim at clarifying the mechanism of accumulation of water at those depths.

Abstract: Natural fiber reinforced polyethylene biocomposites are an environmentally friendly alternative to non-biodegradable thermoplastic materials. The addition of natural fibers to polyethylene improves mechanical properties such as tensile modulus and tensile strength. Unlike thermoplastics, biocomposites are water absorbant due to the presence of natural fibers. Biocomposites mechanical properties degrade when exposed to water. Immersion in water shortens the product life of biocomposites and limits their use in many applications. However, a shorter product life is advantageous for some applications because early degradation reduces the material's environmental impact. The work herein explores long-term water immersion (6000+ hours) of injection molded hemp and wood pulp fiber reinforced polyethylene. Both low density polyethylene (LDPE) and high density polyethylene(HDPE) were tested, each with three fiber fill fractions. The comprehensive dataset collected for this project allowed for conclusions to be drawn about the effect of fiber type, content and distribution as a function of immersion time to predict water absorption. The extent of mechanical degradation was proven to be dependent on the quantity of water absorbed. A model was developed to predict the percentage of water absorbed over a long time scale that accounts for fiber degradation to enable the prediction of changes to the mechanical properties. The prediction of the rate and magnitude of water absorption by natural fiber thermoplastic composites will allow designers to understand, and account for, the degradation of the material's mechanical properties over time.

Electrospinning produces submicron fibers from a wide range of polymer/solvent systems that enable a variety of different applications. In electrospinning process, a straight polymer/solvent charged jet is initially formed, followed by a circular moving jet in the shape of a cone, called the bending region. The process physics in the bending region are difficult to study since the jet diameter cannot be measured directly due to its rapid motion and small size (~microns and smaller), and due to complex coupling of multiple forces, mass transport, and changing jet geometry. Since the solutions studied are hydrophilic, they readily absorb ambient moisture. This thesis explores the role of the bending region in determining the resulting electrospun fiber diameter through a combined experimental and modeling analysis for a variety of hydrophilic polymer/solvent solutions. Electrospinning experiments were conducted over a broad range of operating conditions for 4 different polymer/solvent systems. Comparison of the final straight jet diameters to fiber diameters reveals that between 30% to 60% jet thinning occurs in the bending region. These experiments also reveal that relative humidity significantly affects the electrospinning process and final fiber diameter, even for non-aqueous solutions. A model is developed to obtain insight into the bending region process physics. Important ones include understanding the mass transport for non-aqueous hydrophilic jets (including solvent evaporation and water absorption on the jet surface, radial diffusion, and axial advection), and the coupling between the mass and force balances that determines the final fiber diameter. The absorption and evaporation physics is validated by evaporation experiments. The developed model predicts fiber diameter to within of 8%, even though the solution properties and operating conditions that determines net stretching forces and net evaporation rates vary over a large range. Model analysis reveals how the net evaporation rate affects the jet length and net stretching force, both of which ultimately determine the fiber diameter. It is also shown that the primary impact of RH on the process is through occupation of the surface states that limits solvent evaporation rate, rather than the amount of water absorbed. Correlation functions between process conditions, solution properties and the resulting fiber diameters are discussed.

High pre-harvest rainfall in 2006 caused significant pre-harvest sprouting (PHS) and weathering throughout the mid-Atlantic soft red winter wheat (SRWW) (Triticum aestivum L.) growing region. Sprouting and weathering caused decreased flour quality due to lowered dough viscosity and decreased ability to withstand mixing and processing for baked goods. Due to its decreased quality, severely sprouted grain is sold for feed, at a lower price per bushel. Pre-harvest sprouting negatively affects the chain of production from the field to baking operations. The purpose of this research was to evaluate the inherent dormancy and PHS resistance, of current SRWW cultivars and to assess the relationship between falling number and flour quality after grain weathering. Employing a weighted germination index (WGI), a large range in dormancy was observed across SRWW cultivars and seed production. Artificial weathering tests confirmed the use of WGI as a tool for screening for dormancy of SRWW cultivars. The WGI consistently identified cultivars with significantly higher or lower inherent dormancy. "Coker 9553" was highly dormant and resistant to PHS. This cultivar maintained an average falling number of 300 seconds even after receiving an average of 215 mm of rainfall, while the mean falling number for all SRWW cultivars after this amount of weathering was 131 seconds. After only moderate weathering, nine of 15 SRWW cultivars in the study exhibited severe sprouting, demonstrating the need for increased PHS resistance in SRWW wheat. Pre-harvest sprouting resistance groupings, based on average 2008 cultivar falling number were accurately predicted by WGI at both 10 (R2=0.79) and 30°C (R2=0.72) No consistent relationship was observed between head angle, glume tenacity or awn length and PHS resistance. Water absorption, dough stability, farinograph arrival and departure times, peak, and 20-minute drop were measured from grain samples with varying degrees of weathering. All parameters were negatively affected by weathering in 2008. Flour quality parameters were more affected by genotype than falling number suggesting that falling number should not be used as the sole indicator of flour quality after grain weathering. It is clear that there are vast differences in dormancy levels and PHS resistance among SRWW cultivars and stronger dormancy and higher resistance to PHS does not automatically ensure higher quality flour.

Although it is known that certain organosilanes can dramatically improve the corrosion resistance when deposited on metals, the origin of this effect and its dependence on film characteristics are not fully understood. In this work, the morphology and structure of the silane films, as well as their response to water exposure, are studied mainly by neutron reflectivity. Hydrothermal conditioning and solvent swelling are used to challenge the films. The silanes studied include bis-[triethoxysilylpropyl]tetrasulfide (bis-sulfur) and bis-[trimethoxysilylpropyl]amine (bis-amino) as well as mixed silane films. Initial studies were done on films spin-coated on silicon wafer substrates from 1% solutions and cured at 80 °C. Here the focus is the effect of the bridging group on the morphology and water-barrier properties of the films. Subsequent work addresses the same systems deposited on aluminum substrates, films cured at 180 °C and films of larger thickness. The goal is to clarify the relationship between silane molecular structure, processing variables, morphology and water-barrier properties of films while developing a database for optimizing the performance in anti-corrosion applications. Bridging group is the key factor that controls the morphology and water-barrier properties of silane films. Bis-sulfur silane is not as condensed as bis-amino silane, but it swells less in water because of the hydrophobic nature of bridging group. By contrast, bis-amino film is more hydrophilic since the secondary amine group hydrogen bonds with water. The bulk mixed silane film swells with water to an extent that is slightly less than that of both components weighted by their volume fraction. But, based on the enhanced shrinkage that occurs upon water conditioning of the mixed film, condensation is accelerated in the mixed silane film. Bis-amino silane, may act as a catalyst in the hydrolysis of bis-sulfur silane leading to more silanols groups in the solution, which in turn will improve the wettability of the solution. This effect might explain the superior performance of the mixed film compared to pure bis-sulfur silane film. Processing variables also impact the water-barrier performance. For bis-sulfur silane films, both larger thickness and higher cure temperature are critical for effective water-barrier properties.

Dimethacrylate oligomers diluted with styrene reactive diluents (so-called vinyl ester resins) are becoming increasingly important for composites in applications such as transportation vehicles, printed wiring boards and civil infrastructure. This research has focused on the generation and comparative analysis of glassy dimethacrylate networks as a function of oligomer structure, the type of reactive diluent, composition and curing conditions. A novel cycloaliphatic dimethacrylate was synthesized and its networks were compared to oligomeric structures containing dimethacrylates derived from epoxy terminated oligomers (from bisphenol-A and epichlorohydrin). Both types of dimethacrylates co-cured with methyl methacrylate exhibited increases in Mc and fracture toughness as the concentration of methyl methacrylate was increased. By contrast, networks prepared with a styrene diluent displayed reduced toughness with increasing styrene and Mc. Due to the need for long-term composite environmental durability, the effects of moisture and exposure to sunlight are important. Thus, these materials were exposed to ultraviolet light on a rotating drum for 225 days and the exposure was carefully monitored. Initial results from this study suggest that both the networks comprising the aromatic dimethacrylate/styrene structures as well as the cycloaliphatic analogues cured with methyl methacrylate undergo reductions in rubbery moduli upon aging under these conditions. X-Ray photoelectron spectroscopy shows higher levels of oxidation on the bisphenol-A vinyl ester networks cured with styrene, especially those containing dimethylaniline and cobalt naphthenate as accelerators. Scanning electron microscopy indicates a smooth surface for the cycloaliphatic networks cured with methyl methacrylate and a pitted surface for the aromatic networks cured with styrene. Water absorption is also higher for the cycloaliphatic vinyl ester; however, curing with a longer alkyl chain methacrylate (butyl methacrylate) decreases the water absorption to levels comparable to those cured with styrene.

Applying sizing material (poly n-vinylpyrrolidone or PVP) around graphite fibers enhances the mechanical properties of carbon fiber reinforced epoxy composites. Understanding the influence of the interphase region between the carbon fiber and epoxy matrix is crucial in enhancing the performance of carbon fiber reinforced epoxy composite materials. In this work, simulated interphase regions, in the form of pure and modified epoxies were synthesized in the laboratory. Several characterization techniques were used to identify the properties of these modified epoxies. They were: 1) Tensile Tests: 2) Fracture Toughness Tests; 3) Thermogravimetric Analysis (TGA): 4) Differential Scanning Calorimetry (nSC); 5) Fourier Transform Infrared (FTIR) Spectrometry: and ()) Water Absorption. Young's modulus, yield stress, yield strain. ultimate tensile stress. ultimate tensile strain, tensile toughness, fracture toughness, and strain energy release rate were obtained from tensile and fracture tests. DSC and FTIR experiments were employed in this study to show the miscibility of PVP and epoxy resin. The pure and modified epoxy samples were immersed in water for about a month to determine their water absorptivity. Almost all epoxies remained unchanged in stiffness, with the exception of the sample 40 wt. % PVP. Only the pure epoxy and light PVP loading epoxies exhibited yield points. The ultimate properties worsened significantly with the increase of PVP loading. A decreasing trend was found in fracture toughness as PVP loading increased. All pure and modified epoxies exhibited sharp glass transition temperatures and the Tg's followed the Fox prediction. Downward frequencies shifting of carhonyl and hydroxyl groups were obtained from the PVP/epoxy blends by infrared study. This was believed to show evidence of hydrogen bond formation. All epoxy and modified epoxies were swollen in water absorption experiments. The samples reached equilibrium after about one month and water absorptivity was found to be a function of PVP content. These experiments sought to demonstrate the characteristics of the interphase region of the composites.

The observation that food technologists attempt to minimise seed character variation when using crop products to produce foodstuff stimulated the hypothesis that knowledge of the nature, properties and origins of intra-sample variation would aid prediction of crop product quality. The hypothesis was tested in 3 case studies. Pea seed colour variability was shown to be useful for predicting a pea colour acceptability score derived from ranking studies. In a second case study, wheat seed size variation was shown to have value for predicting flour yield in a number of cultivars. Knowledge of grain protein content improved predictability of flour yield. In one cultivar (Batten) subjected to a wide range of environmental stresses, seed size variability measures, in combination with grain protein content, predicted flour yield, flour water absorption and dough work input requirement as well as current laboratory procedures. Other quality characteristics were predicted well enough for quality segregation purposes. The sources of wheat seed size variability were examined in a head dissection experiment, and observed patterns found to be primarily under genetic control, with random variability restricted to the head-to-head component. A more elaborate experiment is proposed to allow the construction of a cultivar seed size variation "template" against which the random component can be determined more accurately. In the third case study, the relationship between maltability and water uptake variation in barley was investigated. Although a strong relationship between bulk water uptake and maltability was found, and a two-phase seed water uptake model was supported, derived variability statistics could not be used to give useful predictions of maltability. It is postulated that insufficient data were collected to allow the detection of all the double normal distributions that exist (as predicted by the two-phase water uptake model), and to derive reliable estimates of sub-distribution statistics. The results of this case study therefore neither support or refute the hypothesis. More detailed experiments are proposed to obtain more reliable variability estimates against which to compare maltability values. Overall, the data obtained give good support for the hypothesis, but expose the need to identify the fixed, genetically-determined components of variation, so that they can be separated from the random components likely to be the best predictors of environmental impact on quality.