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1
Tian, G. "Renewable materials from renewable resources." Thesis, University of York, 2015. http://etheses.whiterose.ac.uk/11187/.
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Renewable resources related to biomass, waste materials and recycled materials are an important concept in the principles of green chemistry, development of biorefineries and sustainability development. This thesis reports the repurposing of renewable resources which included wheat straw, biomass ash, waste cardboard (paper) and paper de-inking residues (DIR) to extract, synthesize and produce potentially high value chemicals, materials and composites. Biosilicate solutions were successfully extracted from biomass ash including wheat straw ash and miscanthus ash with aqueous potassium hydroxide solutions. Systematic analyses had been applied on the extraction of biosilicate solutions to obtain different types of silicate solutions for further applications of binder and mesoporous materials. Biosilicate solutions extracted from miscanthus ash were utilized as binders to make bioboards, whilst biosilicate solutions extracted from wheat straw ash were utilized as a silica resource to synthesize biobased mesoporous materials, namely bio-MCM-41 and bio-SBA-15. N2 porosimetry analysis revealed that mesoporous silica made from biosilicate solutions gave a surface area of bio-MCM-41 of >1000 m2 g-1 and a surface area of >800 m2 g-1 for bio-SBA-15. XRD, SEM and TEM analyses for both bio-MCM-41 and bio-SBA-15 revealed significant ordering pores, structure and the hexagonal arrays. Different kinds of renewable resources including wheat straw, pea pod waste and paper de-inking residue with the binder of biosilicate solutions and other chemical additives such as protein and starch were processed to bioboards. Also, wheat straw powder was added into cardboard/paper sheets to decrease the cost of paper manufacture and to improve mechanical properties. De-waxed wheat straw cardboard/paper sheets was successfully incorporated in to paper pulp to give a tensile index of 30-34 Nm/g similar with respect to conventional cardboard paper (tensile index of 30-32 Nm/g). A brief study to elicit sugars to the surface of cardboard/paper thus producing an in-situ sticky surface using low temperature microwave irradiation was conducted. Although it’s not conclusive, an aqueous fraction was expelled that contains organic matter (based on C-H stretch absorption bands noted in FT-IR), which may be due to sugars.
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McElroy, C. R. "Composite materials from copolymers incorporating renewable resources." Thesis, Keele University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491843.
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A robust method for the production of an emulsion polymer based on styrene-acrylic acid-acrylic ester was developed to give enhanced physical properties and/or reduced envhonmental impact. Replacing the methyl methacrylate content with n-butyl acrylate, tert-butyl acrylate and ethyl acrylate all gave stable polymer emulsions. Replacing methyl methacrylate with fatty acid based monomer containing no more than one polymerisable acrylate group per molecule also led to the production of a stable emulsion, with the fatty acid based monomer also acting as a self-emulsifying agent if having sufficient amphiphilic character. All stable emulsions were successfully used to produce composite materials.
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Key, Philip Henry. "Excimer laser micromachining of inorganic materials." Thesis, University of Hull, 1989. http://hydra.hull.ac.uk/resources/hull:11090.
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Elaigwu, Sunday Enenche. "Pollution reduction with processed waste materials." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:8424.
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This research aimed at providing an understanding into the waste management options available for developing countries and also to provide insight into the possible application of the processed materials during the waste management processes, thereby helping in converting the waste materials which would have been a nuisance into useful products. Pyrolysis and composting were utilized as the waste management techniques for processing the waste materials for use in pollution reduction. Carbon materials (biochar and hydrochar) were prepared in the pyrolysis aspect of this research through dry and wet (hydrothermal carbonization) pyrolysis respectively. Under the wet pyrolysis, comparisons were made between the conventional and the microwave-assisted hydrothermal process for carbonisation of waste materials. Three waste materials were investigated Prosopis africana shell (from Nigeria), rapeseed waste (from the UK) and coconut husks (a well-studied material in carbon science). The result shows that the microwave-assisted hydrothermal carbonization process reduced the processing time from 4 hours to 20 minutes for the same level of carbonisation. The biochar and the hydrochar from the pyrolysis and microwave-assisted hydrothermal carbonization of one of the waste materials (Prosopis africana shell) were applied in the adsorption of Pb²⁺ and Cd²⁺ from aqueous solution. In terms of adsorbing the heavy metal ions from aqueous solution, the materials proved to have high adsorption capacities than some previously studied adsorbents. Maximum adsorption capacities for the hydrochar and biochar were 45.3 and 31.3 mg/g for Pb²⁺ and 38.3 and 29.9 mg/g for Cd²⁺ respectively. Interestingly, the hydrochar from microwave-assisted hydrothermal carbonization, which is a green chemistry approach, was capable of adsorbing the metal ions more than the biochar from aqueous solution. The adsorption process was dominated by chemisorptions as it followed the pseudo-second-order kinetics and the adsorption data fitted the Langmuir isotherm model. The thermodynamics study of the adsorption processes showed that it was spontaneous and endothermic. Microwave-assisted hydrothermal process and evaporation-induced self-assembly (EISA) were also used to synthesize carbon monoliths, using a waste plant material as the carbon precursor. The microwave-assisted hydrothermal process was not successful in the synthesis of the carbon monolith; however novel carbon monolith was produced using the EISA approach. The carbon monolith in comparison to the biochar and hydrochar from the same material is not powdered, has higher surface area and porosity which could enhance its adsorption capacities for heavy metal ions. In the composting aspect of the research, the Prosopis africana shell showed that it can be composted. The effect of an organic pollutant, in this case anthracene during a starch amended co-composting process was evaluated through total dry matter and extracellular enzyme activities of both starch specific (α-glucosidase) and non-specific (β-glucosidase) substrate. The result showed that the effect of anthracene amendment alone was not highly significant on the process. However, the interaction between the anthracene and starch have consistent effects on the process, which is novel and should be studied further to know the magnitude of sure interaction. This research showed that the waste material (Prosopis africana shell) from Nigeria can be processed into useful products using pyrolysis and composting. Further work will be required in Nigeria outside the laboratory to see the real applicability of these processed materials.
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Thompson, Benjamin Robert. "Hierarchically structured composites and porous materials." Thesis, University of Hull, 2017. http://hydra.hull.ac.uk/resources/hull:16570.
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This thesis develops a hydrogel bead templating technique for the preparation of hierarchically structured composites and porous materials. This method involves using slurries of hydrogel beads with different size distributions as templates. Mixing hydrogel beads with a scaffolding material and then allowing the scaffold to harden, followed by drying of the composite leaves pores in the place of the hydrogel beads. These pores reflect the size and shape of the templates used and the porosity reflects the volume percentage of hydrogel bead slurry mixed with the scaffolding material. A viscous trapping technique has been developed which utilises the viscosity of methylcellulose to stop sedimentation of the scaffold particles during network formation. Both of these methods are attractive due to being cheap, non-toxic and they use food grade materials which allows their use in a multitude of applications. Porous and hierarchically porous gypsum composites have been prepared using both hydrogel bead templating and viscous trapping techniques, or a combination of the two. The level of control over the final microstructure of the dried composites offered by these techniques allowed for a systematic investigation of their thermal and mechanical properties as a function of the pore size, porosity and hierarchical microstructure. It has been shown that the thermal conductivity decreases linearly with increasing porosity, however it was not dependent on the pore sizes that were investigated here. The mechanical properties, however, were significantly different. The porous composites produced with either small hydrogel beads (100 μm) or methylcellulose solution had approximately twice the compressional strength and Young’s modulus compared to the ones produced with large hydrogel beads (600 μm). The sound insulating properties of porous and hierarchically porous gypsum composites have also been investigated. With increasing porosity, the sound transmission loss decreases, as expected. At constant porosity, it is shown that the composites with large pores perform significantly better than the ones with small pores in the frequency range of 75-2000 Hz. At higher frequencies (>2400 Hz) the composites with smaller pores begin to perform better. The material’s microstructure has been studied in an attempt to explain this effect. The hydrogel templating technique can be used to prepare composite materials if the drying step is not performed. Hydrogel beads have been incorporated into a soap matrix. The dissolution rate of these composites as a function of hydrogel bead size and volume percentage of hydrogel beads incorporated within the soap matrix has been investigated. It has been shown that the dissolution rate can be increased by increasing the volume percentage of hydrogel beads used during composite preparation but it is independent on their size distribution. Finally, three methods of controlling the release rate of encapsulated species from these soap-hydrogel bead composites have been shown. The first method involved varying the size distribution of the hydrogel beads incorporated within the soap matrix. The second involved changing the concentration of the gelling polymer and the final method required co-encapsulation of an oppositely charged polyelectrolyte. A binary hydrogel system has been developed and its rheological and thermal properties have been investigated. It consists of agar and methylcellulose and shows significantly improved rheological properties at high temperatures compared to agar alone. The storage modulus of the two component hydrogel shows a maximum at 55 °C which was explained by a sol-gel phase transition of methylcellulose, evidence of which was seen during differential scanning calorimetry measurements. After exposure of this binary hydrogel to high temperatures above the melting point of agar alone (> 120 °C), it maintains its structure. This suggests it could be used for high temperature templating or structuring of food products. The melt-resistant binary hydrogel was used for the preparation of pancake-hydrogel composites using hydrogel bead templating. Mixing slurry of hydrogel beads of this composition with pancake batter, followed by preparation at high temperatures produced pancakes with hydrogel beads incorporated within. Bomb calorimetry measurements showed that the caloric density could be reduced by a controlled amount by varying the volume percentage of hydrogel beads used during preparation of the composites. This method could be applied to other food products such as biscuits, waffles and breakfast bars. Furthermore, there is scope for development of this method by the encapsulation of flavour enhancing or nutritionally beneficial ingredients within the hydrogel beads.
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Haq, Bibi Safia. "Laser structuring of materials for biomedical applications." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:8727.
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Laser processing methods have become very appealing for the fabrication of micro/nano structures. To fabricate 3D structures with high resolution and arbitrary complexity, several material deposition processes are in use. By using appropriate moulding techniques, these structures can be fabricated out of a variety of materials such as polymers, ceramics and composites. In this work different lasers have been investigated regarding their suitability for additive and subtractive patterning of small features for biomedical applications. The main focus is on a technique based on two-photon polymerisation of photosensitive materials; this is a nonlinear optical stereo lithography which allows direct-writing of high-resolution three dimensional structures. During the two-photon absorption process, temporal and spatial overlap of photons leads to nonlinear absorption in a highly localized volume. Absorbed photons induce chemical reactions which cause a polymer to form. Due to the quadratic intensity dependence of the process, resolutions of less than 100nm in polymerized structures can potentially be achieved because of the well-defined polymerization threshold. Here, we have emphasised another regime whereby deep structures (~300µm) can be generated in a single pass. This allows rapid fabrication of structures suitable for cell scaffolds where the length scales are small (~10µm) and are required over long ranges (~cm). A Ti: sapphire femtosecond laser at 800nm wavelength with 150fs pulse duration and 1kHz repetition rate was used to determine the two-photon absorption cross section of photoinitiators. This approach was used to initiate two-photon polymerization of resin allowing the fabrication of cell scaffolds suitable for biomedical applications. Diffraction calculations for the imaging optics employed, show that spherical aberration plays a significant role in determining the feature sizes achieved. For subtractive patterning of materials, a femtosecond laser system and an ArF excimer laser have been used. Using ablative techniques keratin films were processed to investigate physical realisation of the commonly used theoretical bricks-and-mortar description of skin. This structure was successfully fabricated and is being used for skin cream research. Also the threshold fluence for ablation of Polyimide Kapton (HN) foils has been measured at oblique angles as an analogue for corneal sculpturing based on beam scanning.
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Rocher, Anais. "Particles at fluid interfaces : behaviour and derived materials." Thesis, University of Hull, 2011. http://hydra.hull.ac.uk/resources/hull:5738.
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The objectives of this thesis are to enhance the understanding of the particle behaviour at fluid interfaces using novel and stimuli responsive particles, and how their adsorption at these interfaces affect the emulsions, foams or other materials that they are stabilising. Materials stabilised solely by particles are of great interest due to long-term stability, generally low emulsifier content and also in order to replace surfactant molecules, which are often potentially harmful with relatively inert solid materials. The adsorption/desorption of a particle from an interface depends on the particle wettability, which can be affected by the temperature, the pH or the liquid type used, to cite only a few examples. This is investigated through six different sections encompassing particle-stabilised emulsions, particle-stabilised foams and dry liquids. The synthesis of stimuli-responsive particles and their use for production of stimuli-responsive materials is a recent area of interest particularly for bio-medical applications. It is shown in this thesis that temperature has a strong effect on the stability of water-in-oil emulsions stabilised by microwax particles. Separation of wax-stabilised emulsions can be controlled by changing the storing temperature of these emulsions: increasing the temperature results in melting of the wax, destabilising the emulsions. Conversely, the same wax particles give really stable emulsions at elevated temperature, due to potential release from the particles of surface-active molecules. Although it is observed more as a time than as a temperature effect, emulsions stabilised with biodegradable polymer particles undergo analogous separation. The initially high stability oil-in-water emulsions destabilise over time, most likely because of degradation of the polymer particles. It is observed that modification of the polymer particle surface, by grafting pHsensitive groups on their surface, hinders emulsion separation. It is also shown that sporopollenin particles, originated from natural Lycopodium clavatum spores, show a change in charge and wettability with pH. This leads to emulsion inversion from oil-in-water at their high natural pH to water-in-oil at low pH. Interestingly, the sporopollenin particles also exhibit preferred orientation around water droplets: the anisotropic sporopollenins orientate with their hemispherical side toward the oil either for a better packing geometry or due to a wettability difference. The production of new particle-stabilised materials is another concern for this study. The production of novel emulsion drop architectures by using emulsion heteroaggregation has been attempted. Although aggregation of opposite-charge emulsion drops has been found difficult to obtain, the importance of pH, method used for mixing and excess of free particle in the continuous phase is discussed. It is also shown that the number ratio of small to large drops affects the drop aggregation. Another new material produced in this study is particle-stabilised non-aqueous foam. Fluoroethylene microparticles are observed to disperse in low surface tension oil, to stabilise air bubbles when aerated with intermediate surface tension oil, and to form a powder like material with high surface tension liquids. The effect of particle type, oil type and particle concentration on these foams are described, and freeze fracture electron microscopy is used in order to observe the close-packed arrangement of particles at the air-oil surface. Finally, production of a powdered emulsion is attempted in order to encapsulate low volume fraction of oils in a dry material. For this purpose, particle-stabilised oil-in-water emulsions were produced, before being blended with hydrophobic particles, resulting in an encapsulation of emulsion drops into particles. It is shown that the particle type, both for the initial emulsions and production of the powdered emulsions, the particle concentration, the blending time and the oil volume fraction affect the nature of the material obtained.
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Alzahrani, Eman Saad. "Investigation of monolithic materials for protein sample preparation." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:7149.
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Proteomics plays an important role in the recognition of diseases and the understanding of biological processes. Sample preparation is a bottleneck in systems for chemical analysis and it is a required step in proteomics in order to remove interferences and preconcentrate the proteins. In addition, protein reduction and alkylation before digestion is a required step in proteomics to facilitate protein unfolding and increase the efficiency of enzymes in digesting proteins. The purpose of this study was to develop new techniques to address some of the shortcomings of current sample preparation methods, and provide short sample preparation time. Much research in recent years has focused on porous monolithic materials since they are highly permeable to liquid flow and show high mass transfer compared with common packed beds. This study has focused on the use of organic polymer- and inorganic silica-based monolithic materials for protein sample preparation. The organic polymer monolith used in this study was a butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolith that was fabricated inside the borosilicate tube using photoinitiated polymerisation. The porous properties of the fabricated monolith were controlled by adjusting the composition of the porogenic solvent in the polymerisation mixture. The results indicated that using MeOH/1-propanol as a porogenic solvent produced a polymer-based monolith with high surface area (56.89 m² g¯¹); however, it lacked the desired permeability and porosity when fabricated inside a glass microchip. Evaluation of its performance was carried out by extraction of four standard proteins that were insulin, cytochrome C, myoglobin, and hemoglobin and the extraction recovery was in the range (79.1-98.4 %). A monolithic silica rod was fabricated without cracks inside a heat shrinkable tube and then compared with the same material whose surface has been modified with octadecyl groups in order to use them for preconcentration/extraction of proteins. Their performance was evaluated using eight standard proteins, namely insulin, cytochrome C, lysozyme, myoglobin, β-lactoglobulin, ovalbumin, hemoglobin, and bovine serum albumin. The results show that recovery of the proteins was achieved by both columns with variable yields; however, the octadecylated silica monolith gave higher recoveries (92.7 - 109.7%) than the non-modified silica monolith (25.5 - 97.9%). This was followed by a new process for the fabrication of a silica-based monolith inside a glass microchip, which was successfully developed for use in microchip-based solid phase extraction of proteins. This was achieved by placement of the monolithic silica disk inside the extraction chamber in the base plate of the microchip, followed by thermal bonding of the two plates of the glass microchip at 575 °C for 3 hours. By doing this, the problem of shrinkage in the silica skeleton during preparation was avoided completely. The monolithic silica disk inside the glass microchip was subsequently modified with octadecyl groups for increased protein binding capacity. The performance of the microchip was evaluated using the extraction of standard proteins mixed with a high concentration of the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). The results show that the octadecylated silica monolith was permeable, has the ability to remove impurities, and achieved a high extraction recovery of the proteins (94.8-99.7%) compared with conventional octadecylated silica particles (48.3-91.3%). The intra-batch and inter-batch RSDs were in the range of 2.0-4.5% and 2.9-6.4%, respectively. Comparison between the fabricated device and a commercial cartridge for the preconcentration of proteins in skimmed cows milk and hen egg white showed the ability of the device to successfully enrich protein mixtures from more realistic samples. This new microfluidic device for protein extraction may find an application in the area of proteomic research. A novel approach for immobilisation of the reducing reagent on the surface of the silica-based monolith in order to use it for protein reduction and alkylation was successfully developed. This was carried out by silanisation of the surface of the silica-based monolith with (3-aminopropyl)triethoxysilane (APTES), followed by immobilisation of the reducing reagent, tris (2-carboxyethyl) phosphine hydrochloride (TCEP) on the surface of the amino-bonded silica monolith. The fabricated monolith was characterised using IR spectroscopy, EDX analysis, BET model, and measuring the contact angle of deionised water. The fabricated monolith was evaluated for its use in protein reduction and alkylation in one single step at 60 °C by injection of a mixture consisting of 40 μL denatured protein and 60 μL iodoacetamide solution into the fabricated microchip, followed by using MALDI-TOF-MS instrument for qualitative confirmation. The results show that the fabricated microchip-based silica monolith has the ability to reduce and alkylate insulin in 30 min, and lysozyme in 45 min. Although this method was shown to require sample desalting to remove denaturant (urea) and the performance of the fabricated monolith had low intra-chip reproducibility, the method was simple, reduced the risk of contamination, decreased the number of processing steps, and results in lower amounts of the sample and reagents compared with the conventional techniques for proteomics sample preparation. More work is required to fully optimise this approach to protein sample preparation.
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Benstead, Michael. "Dipyrrin complexes and their uses as self assembling materials." Thesis, University of Hull, 2010. http://hydra.hull.ac.uk/resources/hull:4241.
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Several series of BODIPYs bearing mesogenic substituents were synthesised and their fluorescence and liquid crystal properties were characterized. Each compound prepared consisted of one BODIPY fluorophore and one, two or three mesogenic units based primarily on a cyanobiphenyl core. Initially, the mesogens were attached to the pyrrolic positions of the fluorophore, but it was found that mesogen attachment at the BODIPY 8-phenyl ring gave an increased preference for mesophase formation due to the molecules having a more rod-like‘ (calamitic) shape. For several of the compounds, a monotropic nematic phase was exhibited, however, no layered phase (e.g. smectic) was observed. Several linker groups between the mesogenic unit and the fluorophore were investigated and it was found that linear linker groups (e.g. ethynyl) had a greater preference for liquid crystal phase formation when compared to non-linear linker groups (e.g. triazole). Two series of di-mesogenic compounds were prepared and a significant stabilisation of the nematic phase was observed when compared to the mono-mesogenic analogues. The compounds bearing the mesogenic units on the 8-phenyl ring were prepared by metal-catalyzed couplings and each series consisted of three compounds with increasing alkyl substitution on the bipyrrolic core of the BODIPY. This resulted in a progressive increase in fluorescence quantum yield of the compounds in each series due to increased rotational restriction of the 8-phenyl ring along with a concurrent decrease in nematic phase stability. This permitted the observation of a structure-property relationship between nematic phase stability and fluorescence intensity. A BODIPY with significantly red-shifted fluorescence was also prepared and three mesogenic units were attached to this compound. Temperature dependant fluorescence measurements were taken in order to observe any relationship between fluorescence and degree of molecular ordering (e.g. nematic phase fluorescence compared to isotropic liquid fluorescence) and several of the compounds were dissolved in a commercial nematic liquid crystal and incorporated into a twisted nematic cell in order to observe the affect that molecular alignment (induced by an electric field) had on the fluorescence.
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Zhao, Rui. "Environmental risk management system design for hazardous waste materials." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:6227.
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Hazardous materials can be generally deemed as any material which, because of its quantity, concentration, or physical, chemical, or infectious characteristics, may cause, or pose a substantial or potential hazard to human health or the environment. In the context of "sustainable development", most 'materials' could be deemed to be 'hazardous' at some stage of their lifecycle, i.e. from extraction to final disposal. This PhD study develops a decision support system for engineers and policy makers to help limit environmental burden, by reducing the environmental risk and the associated carbon footprint, from the perspective of 'hazardous' materials in product design, through the application of 'game theory' and 'grey theory' etc, as well as various computational approaches, by helping the designer identify novel solutions or mitigation strategies. The thesis starts by introducing the problem situation of the study and identify the research objectives, as well as previous studies have been reviewed in order to set this study in context. Since it is evident that consumers drive the open market, and their preference may be influenced by the carbon footprint label of products, the decision support system proposes an improved carbon labelling scheme to demonstrate the significance of a product‘s carbon footprint in a more visual way. The prototype of the scheme is derived from the concept of 'tolerability of risk', providing a framework by which judgments can be made as to whether society will accept the risk from hazardous materials. Application of game theory for decision support is a novel approach in this study, which aids decision-making by selecting appropriate strategies for both organisations and policy makers to reduce environmental impact. In this context, a game between manufacturers and government in the field of clean production is generated with various game scenarios to reflect the variation trend of strategic actions, and then developed to discuss the reduction of the inherent risk posed by 'hazardous' materials and carbon emissions on the supply chain network. The 'hierarchy of waste' suggests that the most preferable state for sustainability is prevention or the elimination of waste. Although this is not wholly practicable in real terms, the framework gives the importance to waste minimisation and prevention, especially promotes the cleaner production. In addition to strategy selection for mitigating environmental impact, the decision support system also develops an evaluation methodology for application by engineers to aid decision-making on materials selection, thus to improve the materials performances, promote cleaner production and provide better and sustainable products for public consumption.
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Kipling, Gary David. "Modelling the fracture of advanced carbon and related materials." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:6843.
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This thesis outlines the development of a novel computational model which is used to simulate the mechanical response of nuclear graphites on a microstructural scale. Application of finite element analysis (FEA) to the simulated microstructure models allows for the determination of material properties and demonstrates the effect of porosity on these outputs. Further, a methodology for crack propagation through the model enables the simulation of load-displacement curves and fracture parameters. A comprehensive microstructural characterisation programme was undertaken to ascertain pore data for use in computational models. Composite images were generated through optical microscopy in order to sample large areas (10 x 10 mm) of the graphite surface. Results for this work demonstrated the inherent variability of graphite and successfully quantified the pore size distribution. Extensive mechanical testing was undertaken to determine the failure distribution of graphite and two additional brittle materials (glass and ligament material). Biaxial and three-point flexural experiments were employed in order to test a large number of samples. Data from these test programmes was determined to be consistent with a normal distribution and did not provide conclusive evidence for disparate flaw populations. Additional experimental tests were performed to provide data that could be used in the determination of suitable modelling input parameters. Development and solution of the microstructure model allowed accurate representation of pore distributions in an FEA environment which in turn enabled computationally derived mechanical properties to be determined. These properties were comparable to values expected of graphite. Additionally, some simulated fracture parameters compared favourably with experimental results. However, not all properties were representative due to the significant geometric contrast between computational models and experimental samples.
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Callahan, Cory Saye John W. "Educative curriculum materials." Auburn, Ala, 2009. http://hdl.handle.net/10415/1588.
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Young, Daniel James. "Synthesis and evaluation of some novel ferroelectric liquid crystal materials." Thesis, University of Hull, 1989. http://hydra.hull.ac.uk/resources/hull:3804.
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Komandla, Srinivas Reddy. "The synthesis and evaluation of ferroelectric liquid crystal host materials." Thesis, University of Hull, 2015. http://hydra.hull.ac.uk/resources/hull:13091.
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This research is based on the synthesis and evaluation of liquid crystalline host materials for use in ferroelectric liquid crystal devices. The liquid crystal materials are synthesised by incorporating silane bulky end groups linked by an alkoxy spacer to a fluoroterphenyl molecular core. The main aim of the research is to improve the alignment quality with the ultimate aim of bookshelf alignment. Almost as important is the target of wide temperature range, high tilt, and low melting SmC phase materials, but maintaining the low rotational viscosity of the fluoroterphenyl core. The syntheses are reported of a series of silane compounds with bulky terminal groups attached to mono-, di-, and tri-fluoroterphenyl cores. The initial targets contain a pentamethyldisilane end group, but the route was unsuccessful so simpler targets with a butyldimethylsilane bulky end groups were prepared. The key part of the synthesis involves hydrosilylation, low temperature directed lithiation and Suzuki-Miyaura coupling reactions. The report discusses the syntheses and transition temperatures obtained from DSC and thermal polarising optical microscopy. The trends in the transition temperatures, and tilt angles of derived FLC materials, values are discussed and compared to literature compounds. An exemplar is the addition of a chiral dopant (BE8OF2N) to butyl(6-((4''-((10- (butyldimethylsilyl)decyl)oxy)-2',3'-difluoro-[1,1':4',1''-terphenyl]-4-yl)oxy)hexyl)dimethylsilane 30a produces a high SmC* tilt angle of around 45° which varies little with temperature and there is a step in Ps data. This example 30a is mixed in percentages up to 50% with a model difluoroterphenyl KC1020 substituted in the middle ring. The bulky end group suppresses the N and SmA phase when compared to the dialkyl mesogen. A marked reduction in crystallisation temperature shows eutectic behaviour which is promising for ferroelectric mixture formulation. The same example 30a mixed with KC1019, fluorinated on the end ring, has similar behaviour, but with more support of the SmC phase. Other silane materials are mixed with KC1020 only, and their phase behaviour is discussed. Selected 50% mixtures of 30a+KC1019, 30a+KC1020, and an end ring monofluoroterphenylbutyldimethylsilane 39+KC1020 are doped with 7% w/w of standard dopant BE8OF2N(-S) aimed at the ideal phase sequence I-N*-SmA*-SmC*-C. The SmC* tilt angles are close to the ideal value of 22.5° at room temperature but Ps values vary.
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Dixon, Mark S. "The synthesis of liquid crystalline materials for organic semiconductor device applications." Thesis, University of Hull, 2009. http://hydra.hull.ac.uk/resources/hull:2180.
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This research is based on the synthesis and evaluation of novel photo- and chemically-reactive, liquid crystalline monomers (reactive mesogens) with improved charge-transporting properties. Low-molar-mass (LMM) liquid crystalline monomers, based on a series of substituted dibenzothiophenes, thiophenes, [2,2']-bithiophenes, thieno[3,2-b]thiophenes, benzo-2,1,3-thiadiazoles and fluorenes have been synthesised. These materials incorporate photo-polymerisable (non-conjugated diene and methacrylate) and chemically-polymerisable (oxetane) end-groups, attached by aliphatic spacer units of varying length to an aromatic core. These photo- and chemically-polymerisable end-groups are situated at the peripheries of the molecular structure, allowing the potential fabrication of multi-layer, organic semiconductor devices due to the insoluble, cross-linked polymer network obtained after polymerisation of the analogous reactive mesogens (RMs).
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Headspith, David Andrew. "The preparation and characterisation of mixed-anion and non-oxide materials." Thesis, University of Hull, 2009. http://hydra.hull.ac.uk/resources/hull:2680.
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Traditionally, research in solid-state chemistry has focused largely on the chemistry of oxides and on chemical tailoring of the structure and physical properties via cationic substitutions. Consequentially, the chemistry of non-oxide ompounds and other means of chemical tailoring, such as anionic substitutions, have been comparatively overlooked by the scientific community. Non-oxides offer a wide diversity of chemistry, most noticeable in unusual oxidation states and coordination geometries found for metals in these compounds. Furthermore, the development of anionic substitutions could open up an alternative avenue for the modification of the structure and properties in solids and the preparation of novel compounds. The work reported here covers: (1) the preparation of non-oxide compounds (Ba2CoS3, Ba2MnS3, Ce2MnN3, Ce2-xLaxMnN3) and mixed-anion compounds (Ce2MnN3F2-δ, apatite oxide-nitrides) via direct synthesis and/or cationic and anionic substitutions; (2) the characterisation of their structure and (3) the characterisation of selected physical properties. The three-dimensional magnetic cell of Ba2CoS3, which undergoes a transition to long-range order at 46 K, was found to be double the size of the crystallographic unit cell, along the c-axis. A conclusive representation of the magnetic cell of Ba2MnS3, with similar structure to Ba2CoS3, could not be achieved and two possible models are proposed. A one-step synthetic route for Ce2MnN3, more convenient than the route reported in the literature, was developed in this work. Cationic substitutions led to the preparation of the solid solution Ce2-xLaxMnN3 and anionic manipulation of the lattice, via fluorination, led to the preparation of the first example of a quaternary nitride-fluoride Ce2MnN3F2-δ. The structure of Ce2MnN3F2-δshowed layers of distorted MnN5F octahedra and staged fluorine occupancy of the interstitial sites. A range of novel oxide-nitrides were prepared via reaction of the apatite-type oxides La9.33Si6O26, La8+xSr2−xM6O26+x/2 (M = Si, Ge; 0 less than or equal to x less than or equal to 2), La9.67Si5CoO26 and La10M5CoO26.5 (M = Si, Ge) with gaseous ammonia at temperatures above 700°C, most retaining the apatite structure with nitrogen located in interstitial sites.
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Macredie, Robert Duncan. "Principled design guidance for the development of computer-based training materials." Thesis, University of Hull, 1993. http://hydra.hull.ac.uk/resources/hull:10693.
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This study is concerned with the provision of guidance for designers of computer-based training (CBT) materials. Four interrelated principles - immersion, interaction, locative fit, and multiple representations - are discussed. These principles draw upon research into instruction and technology and re-frame and re-interpret established instructional factors in terms of the capabilities of the interactive computer as a training delivery medium. It will be argued that the conjoining of pedagogy and technology in the principles is crucial to the effectiveness of CBT. Furthermore, this study will also argue that the form of the guidance has a direct bearing on its usefulness. The four principles are argued to represent a coherent framework which can raise the awareness of CBT designers on key instructional issues and the ways in which the delivery medium may be used to support them, and provide a resource on which designers may draw. The relevance and effectiveness of the principles (and the issues that they address) are explored through a body of empirical work. This takes the form of two studies: a survey of designers providing comments on the content and expression of the principles and their importance to CBT design; and a series of user trials. The contrasting nature of the studies allows the comments of designers and users to be assessed and compared.
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Rühlicke, Stefanie [Verfasser]. "Saccharides as renewable resources for novel functional materials / Stefanie Rühlicke." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/1225556015/34.
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Doherty, Christopher John. "Living with clay : materials, technology, resources and landscape at Çatalhöyük." Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/40984.
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The Central Anatolian Neolithic tell site of Çatalhöyük has been extensively studied as an unusually well preserved example of an early agricultural settlement. Located on a vast clay plain and occupied continuously for almost 1200 years (7100-5950 cal BC), its large size and artistically rich clay-based material culture point to clay being a major contributor to the community’s subsistence and symbolic needs. However, the prevailing interpretation of the clay-rich landscape appears to contradict this view. Thick impermeable clay beds underlying the areas are thought to have impeded the drainage of seasonal floods, periodically isolating the community in extensive wetlands and forcing a reliance on twelve kilometre distant cereal growing. There is an unresolved tension between the material culture and landscape view of what clay truly afforded Çatalhöyük. The aim of this thesis is to establish the full role of clay in Çatalhöyük’s success, and is first tasked with resolving this tension. The approach taken differs from the top-down single group artifact studies and from landscape models that offer a regional explanation but disregard local actualities. Recognising that clay material culture and clay landscape at Çatalhöyük were intimately linked, this study draws on existing data combined with simple field geology and petrographic analysis to drop down to the common denominator of both of these interacting spheres: clay. The result is a reconstructed landscape interpretation that is no longer at odds either with observed patterns of clay use or broader subsistence practice. The role of clay at Çatalhöyük is re-examined in this more appropriate landscape context to demonstrate a fuller and more complex picture than previously thought. While changing clay use seems to directly reflect past decision making, complex and often hidden feedback between the tell and the immediate landscape was often the real driver for change.
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Bourne, Richard William. "Synthesis and surface modification of nanorods for investigation into organic-inorganic hybrid materials." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:7107.
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The research presented in this thesis is focused towards the synthesis of a new kind of giant hybrid liquid crystal consisting of organic semiconductor molecules surrounding an inorganic semiconductor with a nanorod shape with the potential for use in photovoltaic solar cells. It is intended that such materials will combine the good processing properties of liquid crystals, such as low cost, alignment and photolithographic patterning, with the efficient light emission and electrical conductivity of inorganic semiconductors. Several syntheses of gold and cadmium sulphide nanorods were performed and optimised in order to increase the yield, aspect ratio and monodispersity of nanorods formed. Localised alignment according to Onsager theory was observed for nanorods produced with sufficient aspect ratio and concentration. Investigations into the formation of self-assembled monolayers were carried out using gold nanorods and alkanethiols. Organic synthesis of thiol-terminated ligand groups for attachment to both gold and cadmium sulphide nanorods was performed, and such materials were used for investigations into surface modification of the synthesised nanorods. However, no liquid crystallinity was observed for the organic-functionalised nanorods produced during these investigations. Metal (II) phthalocyanines were used to investigate the formation of chromonic liquid crystalline phases and demonstrated the possibility for an alternative route in producing hybrid inorganic-organic nanorod-like systems.
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Nabhani, Farhad. "The performance of ultra-hard cutting tool materials in maching aerospace alloy TA48." Thesis, University of Hull, 1991. http://hydra.hull.ac.uk/resources/hull:4627.
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A study has been made of the respective performance of cubic boron nitride (CBN) and polycrystalline diamond (PCD) cutting tool materials and compared to various coated and uncoated tungsten carbide grades when cutting titanium alloy workpieces. Two important experimental techniques were employed during the course of this work, firstly a quasi-static contact method was employed to establish the workpiece/tool interfacial temperature above which strongly adherent layers may be formed. This technique revealed that the critical temperatures which marked adhesion and welding, were 740, 820 and 800 °C for coated and uncoated carbides, and 760 and 900 °C for PCD and CBN tools respectively. Furthermore, the technique has been used to study the integrity of the bulk tool material, and/or individual coatings on their substrates, when welded junctions formed between the tool and workpiece are separated. With regard to the latter it was observed that in all cases fracture was initiated in the bulk of the harder tool material rather than in the workpiece or at the welded junction interface. Secondly, a quick-stop technique was used to study chip formation and tool wear when cutting with carbides, CBN and PCD tools under nominally the same conditions. The predominant wear mechanisms for each of the tool materials was found to be based on a diffusion/dissolution process. The wear process is discussed in detail for each of the tool materials and reasons advanced for observed differences in performance when removing material from a titanium alloy workpiece. The wear resistance and quality of the machined surface was found to be superior when cutting with the ultra-hard materials than with the carbide grades and in particular the PCD tool was found to produce exceptionally good surface finish. In the case of coated carbide tool grades rapid removal of the coated layers occurred leaving the substrate vulnerable to reaction with the workpiece material and this is considered to explain the seeming absence of beneficial effects when cutting with these grades.
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Davidsson, Simon. "Natural resources and sustainable energy : Growth rates and resource flows for low-carbon systems." Doctoral thesis, Uppsala universitet, Naturresurser och hållbar utveckling, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-301930.
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Large-scale deployment of low-carbon energy technologies is important for counteracting anthropogenic climate change and achieving universal energy access. This thesis explores potential growth rates of technologies necessary to reach a more sustainable global energy system, the material and energy flows required to commission these technologies, and potential future availability of the required resources. These issues are investigated in five papers. Potential future growth rates of wind energy and solar photovoltaics, and the associated material requirements are explored, taking the expected service life of these technologies into account. Methodology for assessing net energy return and natural resource use for wind energy systems are analyzed. Potential future availability of lithium and phosphate rock are also investigated. Estimates of energy and materials required for technologies such as wind energy and photovoltaics vary, and depend on the assumptions made and methods used. Still, it is clear that commissioning of low-carbon technologies on the scale required to reach and sustain a low-carbon energy system in coming decades requires significant quantities of both bulk materials and scarcer resources. For some technologies, such as thin film solar cells and electric vehicles with lithium-ion batteries, availability of materials could become an issue for potential growth rates. Future phosphate rock production could become highly dependent on few countries, and potential political, social and environmental aspects of this should be investigated in more detail. Material and energy flows should be considered when analyzing growth rates of low-carbon technologies. Their estimated service life can indicate sustainable growth rates of technologies, as well as when materials are available for end-of-life recycling. Resource constrained growth curve models can be used to explore future production of natural resources. A higher disaggregation of these models can enable more detailed analysis of potential constraints. This thesis contributes to the discussion on how to create a more sustainable global energy system, but the methods to assess current and future energy and material flows, and availability of natural resources, should be further developed in the future.
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Bessing, Johan. "Snålandsstolen : Snåla with material resources." Thesis, Linnéuniversitetet, Institutionen för design (DE), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-86010.
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This is a project about how the furniture industry could become more sustainable intheir waste handling. The project is based in Småland both geographically and interms of heritage and history in order to encourage locally produced products. Thecollaborators for this project are the two furniture companies Swedese andStrömslunds Snickerifabrik AB. Both companies have their production in Vaggeryd,Småland. Both companies are struggling with the waste that they produce. The aim ofthis project is to find a sustainable solution for their waste issue. In order to find asolution two theories are applied. The first one is industrial symbiosis which meansthat several industries can, by collaboration, profit from each other’s resources. Thesecond theory is circular economy which encourage remake, reuse or recycling of aproduct once it has reached its end of life. To prove that this solution would be possiblea hunting chair was made by combining the waste material that was gathered fromSwedese and Strömlunds. The decision to make a hunting chair was made to connectthe chair with the heritage of hunting and foresting in rural Småland. The making ofthe chair was different in the way that instead of that the designer would tell thematerial what was possible it was instead the material that decided the limitationsand possibilities. The final product fulfils its purpose and works perfectly for outdooractivities, even though some minor design decisions could have been changed. Theoutcome proves that Swedese and Strömslunds could benefit from working more withcircular economy and start cooperating in order to work as an industrial symbiosis.
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Cameron, Tony Ray. "Alaskan timber resources for wood-plastic composites." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Summer2009/t_cameron_070209.pdf.
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Thesis (M.S. in civil engineering)--Washington State University, August 2009.Title from PDF title page (viewed on Aug. 12, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references.
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Marlow, Gregory. "Week 02, Video 04: Materials." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/digital-animation-videos-oer/17.
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Al-Watban, Ali. "The application of the soft impression technique to evaluate flow stress, creep and frictional deformation of polycrystalline diamond and cubic boron nitride." Thesis, University of Hull, 1996. http://hydra.hull.ac.uk/resources/hull:8054.
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Metal shaping processes are clear examples of engineering applications where a hard material is worn by a softer one - i.e. the tool and workpiece respectively. The soft impressor technique, introduced by Brookes and Green (1973), has proved valuable in measuring the relevant mechanical properties of tool materials - e.g. the measurement of the flow stress of diamond single crystals at temperatures up to 1500°C (Brookes, 1992). In this work, the technique has been extended further in order to form a basis for the comparison and evaluation of ultra-hard materials. Three main aspects of the performance of these tool materials have been covered: the effect of temperature on flow stress; cumulative deformation under point loading conditions; wear due to repeated traversals (fatigue). In the first part, the technique has been extended to determine the flow stress of polycrystalline diamond and cubic boron nitride as a function of temperature and a mathematical model has been proposed to estimate the flow stress in isotropic polycrystalline materials. This model was first analysed by Love (1928) and was used as the basis on which to identify the threshold pressure above which dislocation movement is initiated in diamond single crystals (Brookes et al (1990)). The applicability of this model for polycrystals was verified by correlating the yield strength of polycrystalline copper, measured in tension, with the determination of minimum contact mean pressure to plastically deform the same material. According to the model, the first evidence of plastic deformation should be observed at the contact periphery and this has been verified in this work. Consequently, using this approach, the effect of temperature on the flow stress of polycrystalline diamond (Syndax) and polycrystalline cubic boron nitride (Amborite) has been established and it is shown that there are three distinct regimes. In regime I, the deformation is brittle and fracture occurs above a given mean pressure; in regime II dislocations are mobile and the flow stress decreases sharply as the temperature rises; and in regime III the flow stress is independent of the temperature. In the earlier work, the brittle-ductile transition temperature (BOT) has been identified as that temperature where regime I ends and II begins. Above the BDT, time dependent plastic flow has been observed, in all of these materials, leading to a measurable increase in the size of the impression. However, this particular type of cumulative deformation, described as impression creep, is shown to be different to conventional creep as measured under uniaxial stress conditions. Finally, the room temperature friction and deformation of various polycrystalline diamond based specimens, Le. aggregates with a binder phase of cobalt (Syndite) or silicon carbide (Syndax), a polycrystalline coating produced by a chemical vapour deposition processes (CVDite) and cubic boron nitride (Amborite) were studied when softer metallic and ceramic sliders were used. As a result of increasing the number of traversals, significant wear of the CVDite diamond coating by softer metallic sliders (aluminium and mild steel) was observed. This could be attributed to the high level of residual stresses in the diamond layer which is thought to be due to the difference in the thermal expansion coefficients of the coatings and their substrates. Burton et al (1995) reported a strain of 0.3% on the surface of the diamond coating and hence the tensile stress on the upper side of the coating will be equivalent to about 3.0 GPa. This value is comparable to the theoretical cleavage strength of diamond. It is suggested an additional tensile stress, due to the sliding friction, could have caused cleavage of individual diamond crystals. The resultant wear debris then becoming embedded in the metallic slider. These embedded diamond particles in the tip of the slider could be responsible for the increased friction and wear.
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Aesa, Abdulsattar Ahmad. "Characterisation of laser processed bio-compatible materials and the realisation of electro optical diffraction gratings." Thesis, University of Hull, 2018. http://hydra.hull.ac.uk/resources/hull:16591.
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Laser processing methods using excimer lasers have become very attractive for processing materials and the fabrication of micro and nano optical components. Diffraction gratings are used in a wide range of applications and require different fabrication methods. These components can be fabricated from a variety of biocompatible polymers. In this work, an Argon Fluoride (ArF) excimer laser operating at a wavelength of 193 nm has been used to process chitosan and agarose substrates. These materials have been characterised for differing laser processing conditions. Diffraction gratings and component demonstrators have been realised using Laser Direct writing (LDW) and nanoimprinting lithography (NIL). Characterisation of the ArF 193 nm laser work involves ablation threshold, optical absorption measurements and quantification of structural and morphological changes. This results can be used to identify the ideal laser fluence to be used for the production of a diffraction grating and similar optical components fabricated from chitosan. An ablation threshold of chitosan at 193 nm wavelength has been measured as 85 mJcm−2 and an optical absorption coefficient of 3×103 cm−1. A diffraction grating structure, measuring 12 μm, was generated in biocompatible materials films; chitosan and agarose, using a laser processing method. The results showed that the interaction between the laser and these materials can potentially open the pathway for a wide range of practical, real world applications such as optical and biomedical applications. Diffraction gratings with a feature size of 1 μm were successfully formed on the biocompatible material free standing films using a NIL technique. Microstructure cross grating patterning made of chitosan and agarose have been fabricated by ArF excimer laser processing using a mask projection ablation technique. Temperature rise calculations have been carried out by COMSOLTM Multi-Physics v5.3 using a Finite Element Method (FEM), to predict the temperature rise during laser ablation processing of chitosan and agarose. In addition, COMSOLTM Multi-physics v5.3 has been used to simulate the electric field in the vicinity of a diffraction grating that is illuminated with light from a HeNe laser emitting at a wavelength of 632.8 nm. The final experimental work investigated the possibility of realising 5CB liquid crystal doped chitosan diffraction gratings doped with Sudan Black B (SBB) dye to enhance the absorption properties at 632.8 nm. Diffraction gratings was fabricated using two intersecting beams from a HeNe laser. Polymer Dispersed Liquid Crystal (PDLC) chitosan doped with 5CB and SBB dye diffraction gratings were experimentally characterised.
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Newton, Helen Ruth. "TLM models of deformation and their application to vitreous china ware during firing." Thesis, University of Hull, 1994. http://hydra.hull.ac.uk/resources/hull:3499.
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During firing, the deformation of ceramic articles under their own weight may be problematic particularly in the sanitary ware industry where articles are large. A model has been developed that predicts the viscoelastic deformation of a range of vitreous china testpieces during the firing process. The model constitutes a novel application of the transmission line modelling technique to viscoelastic deformation. The applicability of the model to the sanitary ware industry is addressed.
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Theaker, Ian. "A structural and thermodynamic study of non-aqueous solvent/wax systems." Thesis, University of Hull, 1996. http://hydra.hull.ac.uk/resources/hull:4996.
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Non-aqueous wax/solvent systems of industrial relevance for the manufacture of paste polishes have been investigated. These mixtures have been modelled using a paraffin wax of Japanese origin (Nippon Seiro 140/145°F) in a solution of pure heptane to which dopant components are added.The stability of any resulting gel has been assessed via solubility studies and measurement of the solvent vapour pressure. A new technique for the measurement of vapour pressure in these systems has been developed. The operation of the apparatus has been made almost completely automatic by the use of modern control units.Complementary analytical techniques such as Differential Scanning Calorimetry and Nuclear Magnetic Resonance have been used to augment the data where appropriate and the structure of these pastes has been investigated with the use of Optical Microscopy.
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Marlow, Gregory. "Week 12, Video 03: Character Materials." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/digital-animation-videos-oer/81.
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McConnachie, Jennifer. "Finite element analysis of conformal contacts in water hydraulic axial piston pumps incorporating advanced ceramic materials." Thesis, University of Hull, 1995. http://hydra.hull.ac.uk/resources/hull:14764.
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The use of water as a hydraulic fluid in a pump necessitates the use of conformal contacts to reduce the high rates of wear and leakage losses that result from the low viscosity and lubricity of water. Swashplate type axial piston pumps are ideal in this respect because they incorporate such conformal contacts. Furthermore, the development of such a pump for use with water, especially sea-water, critically relies on the correct selection and application of materials. The purpose of this research work is firstly to examine the contact conditions within an axial piston pump for a range of sleeved and lined components manufactured from a variety of different materials. The use of finite element analysis with gap elements is a useful way of determining the contact pressure distribution between conformally contacting components. It is shown that this method gives excellent agreement with available analytical methods for the two-dimensional cylindrical and axisymmetric spherical cases, and thus can be extended to layered components. Extension to three dimensions, when the contact cannot be accounted for by plane strain or plane stress conditions, is also possible, allowing a much more representative analysis of the contact conditions within an axial piston pump. No single combination of materials is identified as being the most suitable, rather, the method enables the consequences of choosing materials for their tribological characteristics to be examined. Once the contact conditions are known within the pump it is then possible to more accurately design the pump components. However, conventional deterministic methods are not appropriate for designing ceramic components, due to the inherent scatter of limiting defects, and statistical methods are necessary. Thus the second part of this research work is aimed at reviewing and examining the different probabilistic design methods with the long-term view of determining which, if any, are best suited to the design of ceramic components in this particular application. It is conduded that no single method adequately predicts the probability of failure of ceramic specimens with more complex stress distributions than four-point flexure bars.
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Jonker, A., and JH Potgieter. "An evaluation of selected waste resources for utilization in ceramic materials applications." Elsevier, 2004. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000929.
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Many industrial processes generate large amounts of waste. Typical examples include the fertiliser industry (phosphogypsum), ferro-alloy
and steel producers (slag), as well as the power generating industry (fly ash). Although some waste products are currently used to a limited
extend (e.g. fly ash and cement in cement), there is a constant need to find more uses and newapplications for these. This investigation describes
work done to develop a novel ceramic body, which can potentially be used as a ceramic filter for purification of waste water and potable water.
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Marlow, Gregory. "Week 08, Video 02: Arnold Materials." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/digital-animation-videos-oer/56.
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Marlow, Gregory. "Week 03, Video 08: Arnold Materials." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/digital-animation-videos-oer/31.
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Marlow, Gregory. "Week 03, Video 06: Hardware 2.0 Materials." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/digital-animation-videos-oer/29.
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Kopec, Grant Michael. "Examining natural resource futures with material flow analysis." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709409.
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Silva, Kodikara Manjula Dilkushi. "Environmentally friendly packaging materials from renewable resources as alternatives for oil-based polymers." Thesis, Brunel University, 2011. http://bura.brunel.ac.uk/handle/2438/6453.
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Nearly 60 m tonnes of waste is produced annually in Europe from “plastic packaging” engendering significant challenges for legislative controls and minimisation of environmental impact. There is an increasing demand for biodegradable packaging, which can be disposed of with minimum environmental impact, but the growing market is still in its infancy predominantly due to a lack of materials having environmental, practical and economic suitability. This research project dealt with some processing challenges of environmentally friendly packaging materials from renewable resources, as a long term solution to mitigate some issues associated with oil based plastic packaging. In this work, novel Polylactic acid (PLA) and starch based composites were developed with the requisite technical properties to fill the gap in the food packaging and cosmetic packaging industry. It was found that starch can be incorporated in a PLA matrix at the 10% level without difficulty in processing in the presence of 2% methyldiphenyl diisocyante. The blend shows properties similar to pure PLA. It was also found that the elongation at break and impact properties of PLA can be increased remarkably by the addition of a biostrength impact modifier. Furthermore, mixing of PLA and starch in the blend is efficient when the PLA particle size is reduced. It was also found that flexible and tougher PLA/starch blend pellets, that can be injection moulded, can be produced by an extrusion process with a range of additives. Each additive has a maximum level that exhibits optimum properties. The blends also established that 15% starch can be incorporated into the PLA matrix to reduce the cost without any processing difficulties. Encouragingly, the presence of an impact modifier in the PLA/starch blends has shown more desirable properties. Furthermore, the mechanical properties of the pellets exposed to increased residence time in the injection moulding barrel and of the test specimens stored for 9 months at 21ºC were also satisfactory for the new blend. The overall results exhibited some attractive properties in the tri blend system, which can be easily adopted by the plastics industry for development of an injection moulded product within the scope of applications such as dry food packaging or cosmetic packaging. A further finding of this project is that biodegradation under a home composting environment can be improved by incorporating starch and certain other modifiers into PLA.
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AlSuhaimi, Awadh Owyimer. "New materials preparation and miniaturised devices for solid phase extraction as sample preparation techniques for the analysis of transition metals." Thesis, University of Hull, 2006. http://hydra.hull.ac.uk/resources/hull:11513.
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The subject of this thesis is the development of solid phase extraction (SPE) materials and miniaturised apparatus applicable for sample preparation in the analysis of transition elements from environmental matrices. It consists of five main chapters and a general conclusion. The first chapter is a general introduction. Considerable attention is given first to underlining the role of SPE as an efficient sample preparation approach in trace analysis. Subsequently the materials and techniques most frequently exploited for the synthesis of SPE materials specific for metals are discussed with the aid of various demonstrative examples from recent literature. Then the current research trends towards downscaled analytical systems and the efforts to integrate SPE apparatus within miniaturised devices are pointed out. Particular attention is paid to the fabrication techniques predominantly exploited to construct microfluidic devices, i.e., from glass and polymers. Given that the developed SPE systems in this thesis were coupled with various analytical detectors/instruments including atomic spectroscopy (i.e., ICP-OES, ICP-MS), optical absorption spectroscopy (in UV-Vis range) and electrochemical (amperometry) monitoring. the essential fundamentals of these detection techniques are presented. In the second chapter, the development of a rapid and an environmentally friendly chemical transformation, consisting of minimum steps in comparison with the traditional method, to immobilise oxins (i.e., 8-hydorxyquinoline (8-HQ)) on silica surfaces is reported. The produced chelating resin shows excellent performance as SPE materials for on-line sample preparation (preconcentration and matrix elimination) of some transition metals prior to their determination by ICP-OES. The applicability of this SPE material was tested by analysing Cu, Co, Zn, Ni and Pb in the range of 50-300 ng ml-1 from a synthesis matrices simulating sediment. The recovery values were ranged from 100% for Zn to 70% for Ni. The work in this chapter also presented a method to mask the environmentally abundant (major) transition metals (i.e., Fe, Al and Mn). The system used at its optimised parameters to analyse the studied ions from different sediments reference materials. The results show good agreement with the certified values. Chapter three describes methods to fabricate miniaturised SPE columns from monolithic materials. Short monolithic columns were fabricated from silica materials using a simple sol-gel method relaying on the hydrolysis of potassium silicate (21 % Si02, 9% K20) using formamide and/or acetamide, then functionalised with 8-HQ and L-cystiene via two different in situ procedures. The functionalised monolithic microcolumns encapsulated inside a house made connector, and thus easily incorporated within a FI manifold coupled with UV/Vis spectrometer allowing the eluted metals to be derivatised, with chromogenic reagents (i.e., PAR and ferrozine), and monitored on-line. The system has been characterised for Co, Cu and Fe (II). The microcolumns functionalised with L-cystiene operating at flow rate of 0.3 ml min-l for 4 minutes, the linear range for the Co, Cu and Fe (II) ions were 20-240, 10-200 and 5-180 ng ml-1 respectively. For those functionalised with 8-HQ, the linear range were 15-300, 10-250 and 5-250 ng ml-1 in the same order. In chapter four, downscaled SPE apparatus applicable for sample preparation prior to ICP-MS monitoring, have been constructed making use of the lab on a chip concept. Standard photolithography and wet etching were used to fabricate glass microfluidic devices accommodating three microchannels, each of them incorporating a defined section that could be packed with SPE resin. The microdevice interfaced with the ICP-MS instrument throughout a low flow rate concentric nebuliser using a Teflon connector, and coupled with FI delivering sample and reagents via a splitting valve. The feasibility of this miniaturised system to perform SPE of trace metals was proved by analysing trace metals, Cd, Co, and Ni, in seawater reference materials. Chapter five reports two designs to integrate microfluidic devices with electrochemical detection. In the first one, a microfabricated glass microfluidic device incorporating single microchannel with a packed section was coupled with a specially designed miniaturised electrochemical cell in a configuration that permits the working electrode to be mounted opposite to the channel outlet to facilitate end channel amperometric detection. The miniaturised electrochemical cell was made from three pieces of glassy carbon, silver and platinum rods of 2 cm length as working, reference and auxiliary electrodes respectively. These rods were assembled in a miniaturised Perspex block, stabilised with insulating epoxy resin and their ends were polished to mirror like discs. In the other design, the microfluidic devices were fabricated from PDMS by a simple casting and moulding techniques permitting the construction of three dimensional (3D) microchannels. The elastic characteristics of PDMS offer a great degree of flexibility for the placement of the microelectrodes inside the microchannel; thus, the monitoring is performed in-channel. To minimise variation in background current due to the pH change, the SPE process was carried out in buffer media i.e., the metals were loaded in acetate buffer of pH 4.8 and eluted with buffered solution of 50 nM Pyridine-2,6-dicarboxylic acid (PDCA) containing 50 mM of KCI as a supporting electrolyte to maintain a constant conductivity. The system shows good performance in the SPE and monitor Cu ion from standards solution in the range 100-400 ng ml-1 with LOD at 52 ng ml-1 In chapter six a general conclusion and a concise prospective for further work are presented.
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Daniel, Robert David. "The influence of nitrogen on the plasticity of diamond." Thesis, University of Hull, 2000. http://hydra.hull.ac.uk/resources/hull:5900.
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The aim of this work has been to use the soft impressor technique to investigate the plastic deformation of single crystal diamond and in particular to determine the effect that single substitutional nitrogen has on plasticity. Traditionally hardness tests in the form of Vickers or Knoop rigid indenters have been used to investigate the mechanical properties of materials which cannot be fabricated into tensile or three point bend test specimens. The high stress concentrations created by these types of test introduce a large degree of brittle failure in ultra-hard, covalently bonded materials. The soft impressor technique, on the other hand, allows large pressures to be applied without large stress concentrations. The result is that plastic deformation can be more readily induced into super hard materials such as diamond. This work has shown that not only can diamond be readily plastically deformed but that traces of nitrogen impurities within the lattice have a significant effect on the conditions necessary to produce dislocations. For this work, several different soft impressors were used to produce a range of pressures in the temperature range 800° to 1400°C. A selection of synthetic (HPHT) diamonds with various nitrogen concentrations were impressed and compared with impressions placed in natural type IIa specimens containing no nitrogen but heavily dislocated. Numerous analytical techniques were used to determine the level of deformation produced and gain a better understanding of the effect of nitrogen related defects. The first two chapters of this thesis review, first plasticity and then diamond, with reference to those properties/characteristics relevant to this topic. The third chapter discusses the principle of the soft impressor technique and the methodologies used. In the fourth chapter, models by which single crystal diamond plastically deforms are introduced, together with results that have extended the brittle-ductile transition schematic produced by Brookes, EJ. (1992). Results on the effect of dwell time and the phenomenon of impression creep are also presented. The fifth chapter identifies the predominant defects associated with substitutional nitrogen in HPHT diamond and presents profiles of impressions for diamonds with different 'grown-in' defect levels. The results are discussed and conclusions are made, in conjunction with suggestions for further work in chapter 6.
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Lesser, I. O. "Resources and strategy : Raw materials in strategic thought and prtactice from the industrial revolution to the present." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234319.
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Miah, Abdul J. "Automated library networking in American public community college learning resources centers." Diss., Virginia Polytechnic Institute and State University, 1989. http://books.google.com/books?id=5LbgAAAAMAAJ.
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Thesis (Ed. D.)--Virginia Polytechnic Institute and State University, 1989.Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 148-159).
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Edens, Kolbi. "Effects of Evidence-Based Materials and Access to Local Resources on Physical Activity during Pregnancy." TopSCHOLAR®, 2019. https://digitalcommons.wku.edu/theses/3101.
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Williamson, Gregory Scott. "Investigation of Testing Methods to Determine Long-Term Durability of Wisconsin Aggregate Resources Including Natural Materials, Industrial By-Products, and Recycled/Reclaimed Materials." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/31822.
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The Wisconsin Department of Transportation (WisDOT) uses approximately 11,000,000 tons of aggregate per year for transportation projects. Being able to select durable aggregates for use in transportation projects is of considerable importance, if the aggregate deteriorates then the constructed facility requires premature repair, rehabilitation or replacement. Realizing the importance and also that deficiencies in the current WisDOT testing protocol may exist, it has been concluded that the durability-testing program for Wisconsin aggregates needs to be updated. For example, WisDOT is currently using the Sodium Sulfate Soundness Test (ASTM C 88) to measure durability, a test that was put in place in 1960. The ability of this test to predict durability performance and simulate field conditions is questionable and it has also been criticized for its lack of precision.
It should also be noted that the use of recycled and reclaimed aggregates has increased in recent years and not all typical durability tests can be used for testing these aggregates. The Sulfate Test in particular cannot be used for testing Recycled Concrete Aggregates (RCA) because the chemical reaction produces erroneous and misleading results.
This project has identified recent advances in the understanding and testing of aggregate durability. An in depth literature review has been conducted and from the compiled information a laboratory testing program was developed. Selection of the tests was based upon the tests' precision, efficiency, and predictive capabilities. In the laboratory-testing phase of this project the proposed durability tests along with current WisDOT durability tests were used to evaluate the full range of Wisconsin aggregates.
From the test results it was found that the WisDOT aggregate testing protocol could be reduced substantially by eliminating many of the testing requirements for aggregates that have a vacuum saturated absorption of less than 2%. Also, the addition of several tests was ruled out due to their lack of correlation with field performance records. The Micro-Deval abrasion test is recommended for inclusion in WisDOT testing protocol as a test to measure the abrasion resistance of aggregate while the L.A. Abrasion test is better suited as a measure of aggregate strength. Additional conclusions were made based on the durability testing conducted and an overall testing protocol has been developed and is recommended for implementation by WisDOT.Master of Science
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Ourique, Pedro Antonio. "Preparação e caracterização de revestimentos híbridos de poliuretano-ureia a partir de fontes renováveis." reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1348.
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O presente trabalho teve como motivação investigar a viabilidade na utilização de polióis, produzidos a partir da oxidação induzida de óleo de soja comercial e utilizar estes como precursores na síntese de revestimentos híbridos de poliuretano-ureia. O óleo de soja foi escolhido por ter baixo custo, ser oriundo de fontes renováveis e apresentar em sua molécula locais com potencialidade para modificação química. Os polióis produzidos por oxidação induzida foram caracterizados por titulometria, espectroscopia na região do infravermelho com transformada de Fourier (FTIR), espectroscopia de ressonância magnética nuclear do próton 1H (RMN 1H), cromatografia por permeação em gel (GPC) para identificar a formação de grupos hidroxila em sua molécula e determinar o tempo adequado de oxidação do óleo. Após serem caracterizados, os polióis foram utilizados na síntese de revestimentos híbridos de poliuretano-ureia para serem utilizados na proteção de superfícies metálicas. Os precursores utilizados na síntese foram o óleo de soja oxidado durante 24 h (OSO-24h), óleo de soja oxidado durante 48 h (OSO-48h), 4,4'-difenil metano diisocianato (MDI), 3-aminopropil trimetoxisilano (APTMS). As análises de FTIR dos revestimentos híbridos revelaram a presença de grupos Si-O-Si, indicando a formação de uma rede híbrida, a qual também foi identificada pela análise de espectroscopia de ressonância magnética nuclear do próton 29Si (RMN 29Si), quando foi verificada a presença de estruturas T0, T1, T2 e T3 (onde o índice 0, 1, 2 ou 3 indica o número de grupos de siloxanos ligados ao átomo de silício). O mapa composicional obtido por espectroscopia de energia dispersiva (EDS) revelou que as amostras contendo aminosilano apresentam estruturas com separação de fase; isto aconteceu devido à diferença na taxa relativa de formação dos grupos ureias frente aos grupos uretanos. As análises de difração de raios X (DRX) exibem um perfil típico de materiais amorfos e a técnica de espalhamento de raios X a baixo ângulo (SAXS) revela que os domínios rígidos possuem formatos esféricos com tamanhos entre 1-6 nm. Os revestimentos aplicados em substratos metálicos foram aprovados nos testes de adesão, resistência ao impacto e flexibilidade segundo as normas da sociedade americana de testes e materiais (ASTM), entretanto, o ensaio de névoa salina revelou que os revestimentos sem o aminosilano apresentam maior resistência à corrosão, em comparado com os materiais híbridos, em virtude da formação de uma fase rica em silício, a qual atua como inicializadora da reação de corrosão.Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2016-10-17T15:37:27Z No. of bitstreams: 1 Tese Pedro Antonio Ourique.pdf: 4145729 bytes, checksum: 0326f707659828778e2d95c67c9e81c9 (MD5)
Made available in DSpace on 2016-10-17T15:37:27Z (GMT). No. of bitstreams: 1 Tese Pedro Antonio Ourique.pdf: 4145729 bytes, checksum: 0326f707659828778e2d95c67c9e81c9 (MD5) Previous issue date: 2016-10-17
Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, FAPERGS.
Motivation of the work was to investigate the synthesis of polyols obtained from air induced oxidation of the commercial soybean oil and use these as precursors in the preparation of polyurethane-urea hybrid coatings. Soybean oil is a feedstock that has low cost, and it comes from renewable sources. This molecule has the potential for chemical modification and use in different applications. The synthesized polyols were characterized by titration, FTIR, 1H NMR and GPC for evaluation formation of hydroxyl groups in oxidized soybean oil. After characterization polyols, were used in the synthesis of polyurethane-urea hybrid coatings for use in metal surfaces protection. The monomers used in the synthesis of hybrid coatings were oxidized soybean oil for 24 h (OSO-24), oxidized soybean oil for 48 h (OSO-48h), 4,4'-diphenyl methane diisocyanate (MDI), 3-aminopropyl trimethoxysilane (APTMS). FTIR analysis of the hybrid coatings revealed the presence of Si-O-Si bands, indicating the formation of a hybrid network, which was also identified by 29Si NMR, showing the formation of structures T0, T1, T2 and T3. SEM analysis and compositional map generated by EDS indicate that the samples with APTMS presented phase separated structures; this occurred during the difference in the relative rate of formation of urea groups when compared to urethane groups. On the other hand, the synthesized materials were amorphous and had rigid spherical shape domains with sizes between 16 nm. The films produced, when used as coatings, exhibited satisfactory mechanical behavior and excellent adhesion to metal substrates. However, its corrosion resistance is limited during of the formation of silicon rich phases.
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Roberts, David M. "Improving the LEED-NC 2009 materials and resources category using international building assessment systems and standards." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041285.
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Hiralal, Popat Pritesh. "1-dimensional nanomaterials for energy generation and storage." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610469.
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Waswa, Anne, and Mitchelle Wambua. "Teaching and Learning of Mathematics in Sweden : Methods, Resources and Assessment in Mathematics." Thesis, Linnéuniversitetet, Institutionen för utbildningsvetenskap (UV), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-45007.
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Zúñiga, Ruiz Camilo Javier. "Polybenzoxazine materials from renewable diphenolic acid." Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/128180.
Full textAbstract:
La síntesis de polímeros a partir de fuentes renovables como la biomasa es una forma viable de resolver los problemas relacionados con la contaminación del medio ambiente y la escasez de recursos derivados del petróleo usados como materias primas en la industria de los polímeros.
Las polibenzoxazinas son una nueva clase de resinas termoestables cuya síntesis es de gran simplicidad y presentan propiedades interesantes de potencial aplicación en diversos campos, entre otros en la industria electrónica. Además, las benzoxazinas eliminan el problema de la liberación de subproductos de condensación, que presentan las resinas fenólicas convencionales, y no necesitan de un catalizador para su entrecruzamiento. También ofrecen una mayor flexibilidad en el diseño estructural al poder utilizar fenoles y aminas de diferente estructura.
Tradicionalmente, las benzoxazinas se sintetizan a partir de fuentes derivadas del petróleo como fenoles, aldehídos y aminas primarias. Son escasos los ejemplos de síntesis de benzoxazinas parcial o totalmente derivadas de fuentes renovables. Dentro de ellas, cabe destacar el uso del cardanol, compuesto extraído del aceite de la cáscara del anacardo, y más recientemente el uso de gliceroles parcialmente enriquecidos, provenientes del aceite de girasol, en la síntesis de polibenzoxazinas con buenas propiedades de flexibilidad y adherencia.
A partir de procesos de biorefineria de la celulosa se obtiene el ácido levulínico. Este compuesto es de gran interés a nivel industrial debido a que su producción es simple y se obtiene con altos rendimientos. Una de sus aplicaciones es como precursor en la producción industrial del ácido difenólico, que se obtiene mediante una reacción de condensación de éste con fenol.
En los últimos años la Organización Mundial de la Salud ha prestado especial atención a aquellas sustancias de uso diario que representan una amenaza para la salud humana. Entre ellas están los ftalatos, las benzofenonas, los parabenos y el bisfenol A (BPA). Actualmente el ácido difenólico se está considerando como una alternativa “green” para sustituir al BPA ya que presenta una estructura química muy similar, es más barato y además posee una funcionalidad extra, que le brinda cierta versatilidad en la síntesis de polímeros.
De acuerdo a todo lo mencionado anteriormente la presente tesis aborda la utilización del ácido difenólico como material de partida para la síntesis de nuevas polibenzoxazinas con un alto valor añadido. De esta forma, diferentes estrategias se han desarrollado para explorar las diferentes aplicaciones de estos materiales que se han agrupado en distintos capítulos, que a continuación se mencionan.
En la primera parte del capítulo 1 se describe la síntesis y polimerización de dos nuevas polibenzoxazinas: la derivada del ácido difenólico (DPA-Bz) y la derivada del éster del ácido difenólico (MDP-Bz). Además, se describe la caracterización térmica y termomecánica de ambos materiales y se comparan con las de la benzoxazina derivada del bisfenol A (BPA-Bz). Como resultado de las reacciones de esterificación o transesterificación entre los grupos hidroxilos, derivados de la apertura del anillo de oxazina, y los grupos carbonilo y éster, presentes en la estructura de las benzoxazinas, la MDP-Bz y la DPA-Bz presentaron una mayor densidad de entrecruzamiento y por ende una mayor temperatura de transición vítrea (Tg) en comparación con la BPA-Bz. En la segunda parte del capítulo se describe la preparación de mezclas entre el DPA y la MDP-Bz reforzadas con fibra de vidrio. La adición de DPA disminuyó la temperatura de polimerización de las mezclas, la Tg y las propiedades termomecánicas debido a su incorporación en la red de entrecruzamiento. Así mismo, se prepararon polibenzoxazinas retardantes a la llama mediante la adición de una sal de fosfaceno derivada del DPA. Los materiales resultantes exhibieron una buena estabilidad térmica.
La primera parte del segundo capítulo trata sobre la preparación y caracterización de espumas rígidas de polibenzoxazina de baja densidad, a partir de la DPA-Bz. A través de un proceso de autoespumado en el cual se genera el agente de espumado (CO2) in situ, debido a una reacción de descarboxilación, se prepararon una serie de espumas controlando la temperatura de espumado. Los materiales resultantes se caracterizaron en función de su morfología, y propiedades térmicas y mecánicas. Un segundo estudio contempló la preparación y caracterización de espumas rígidas de polibenzoxazina retardantes a la llama. Se emplearon 2 compuestos organofosforados y se determinó la incidencia de su adición usando técnicas analíticas. Las espumas demostraron buenas propiedades retardantes y buena estabilidad térmica en comparación con las espumas sin aditivo. Finalmente, usando herramientas analíticas se propusieron modelos matemáticos para ajustar la densidad y las propiedades mecánicas (resistencia y el módulo de compresión) de las espumas retardantes a la llama en términos de las variables de espumado, es decir, la temperatura y el tiempo.
En el tercer capítulo se describe la preparación de nanocompuestos poliméricos. Como matrices poliméricas se usaron la MDP-Bz, la BPA-Bz mientras que como nanoaditivos se emplearon nanotubos de carbono de pared múltiple (MWNT) entre 0.1 y 1.0 % en peso. Con el fin de conseguir un método de dispersión que fuera más respetuoso con el medio ambiente no se empleó ningún disolvente. La dispersión de los nanoaditivos en ambos monómeros se evaluó mediante medidas reológicas mientras que la dispersión en los polímeros se observó usando un microscopio electrónico de transmisión (TEM). En general se obtuvo un buen grado de dispersión en los dos sistemas. La adición de nanotubos tuvo un efecto positivo en los nanocompuestos obtenidos ya que éstos exhibieron una alta conductividad eléctrica, una buena estabilidad térmica y una alta resistencia a la llamaPolybenzoxazines are considered a new type of thermosetting phenolic resins whose synthesis is quite simple. Polybenzoxazines present unique features that make them promising candidates for various industrial applications including electronics, aerospace, composites, coatings, adhesives, and encapsulants manufacturing. Two new benzoxazine materials have been synthesized and polymerized from the renewable diphenolic acid. The diphenolic acid-based benzoxazine (DPA-Bz) enables the preparation of rigid foams as well as flame retardant counterparts through a self-induced foaming process. For the methylester derivative benzoxazine (MDP-Bz), fiberglass reinforced materials were obtained with flame retardancy properties. Moreover, by adding neat carbon nanotubes, nanocomposite materials were prepared with low percolation threshold and improved thermal and fire properties.
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Bryans, Victoria Louise. "Canadian provincial and territorial archival legislation : a case study of the disjunction between theory and law." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/28704.
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This thesis is an inquiry into the nature of current provincial and territorial archival legislation in Canada. It provides an analysis of archival legislation as a form of written communication and argues that the legislation suffers from the same deficiencies inherent in other forms of communication as a result of external social influences on its meaning. Chapter one therefore traces the evolution of the legislation from 1790 to the present and shows how the meaning of current legislative texts emerged neither from objective legal considerations nor archival theory, but as an ad hoc response to a variety of social influences. The remaining chapters are based on a detailed content analysis of the three main components of current provincial and territorial archival legislation: provisions establishing definitions of key terms, provisions establishing the scope and authority of administrative structures for archival programmes and provisions establishing programme elements. They elaborate on the argument advanced in chapter one that the social production of meaning, arising from the manner in which current provincial and territorial archival legislation has developed, adversely affects its ability to promote the preservation of documents in two ways. First, this process
of development has meant that wording in legislative texts carries overtones of outdated attitudes and assumptions about archives. Second, it has led to inconsistency, conflict, vagueness and ambiguity in the meaning of the texts. These chapters also put forth prescriptive ideas regarding how the adverse affects of social influences on the meaning of current provincial and territorial archival legislation might be overcome.Arts, Faculty of
Library, Archival and Information Studies (SLAIS), School of
Graduate
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Harrison, Steve. "An examination of the geological resources of the Southern Highlands of NSW as raw materials for studio ceramics." View thesis, 2007. http://handle.uws.edu.au:8081/1959.7/31721.
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Thesis (Ph.D.)--University of Western Sydney, 2007."A thesis submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy from University of Western Sydney, College of Arts, Centre for Cultural Research." Includes bibliography.