The IKEA customers are looking for new solutions to mount products in their homes and IKEA has embraced the request for this type of applications in bathroom environments as it is of the largest challenges for the customer. Double sided tape has been identified as a possible solution, hence why this project was put together. The research aims to give the reader a deeper understanding regarding double sided tape and the influences of external variables such as material, substrate and surface tension to mention a few. Extensive tests have been carried out where samples from double sided tape suppliers are examined. The test that was developed and carried out in this project aimed to include some of IKEA´s most commonly used materials together with common substrates in bathroom environments. The test data was compiled and the outcome was used to give recommendations to IKEA regarding future product development when using double sided tape and also recommend suitable tape suppliers for continued cooperation.

Measurement and mapping of the pressure distribution across the surface of a suitably scaled model is an integral step in the design of any aircraft or automobile. For this purpose, the traditional workhorses of the aeronautic and automotive industries have been pressure taps--small orifices that contain electronic pressure transducers. Unfortunately, in addition to the limited spatial resolution achievable with such devices, their technical complexity and cost constitute serious disadvantages. For more than 35 years, researchers have pursued a fundamentally different alternative: indirect measurement of pressure via oxygen-induced quenching of the luminescence emitted by certain chemical species. Porphyrin complexes of dipositive palladium and especially platinum have emerged as one of the principal classes of oxygen-sensitive luminophores; ruthenium(II) polypyridyl complexes comprise another. Various other metals also form luminescent coordination complexes that are susceptible to quenching by O2, however, and these too have contributed to the diversity of luminophores that are now available for incorporation into pressure-sensitive paints and related films and coatings. After treating the photophysics of luminescence quenching by molecular oxygen and quantitative descriptions of this phenomenon in the ideal case and in heterogeneous media, the thesis presents a comprehensive survey of the chemical literature on oxygen-sensitive luminophores. Efforts to prepare and characterize a novel porphyrin-pillared mixed zirconium phosphonate are then detailed. Following complexation of Pt(II) ions by the porphyrin moieties, this material is expected to display oxygen-sensitive luminescence and should ameliorate such difficulties as luminophore aggregation and matrix photodegradation that are associated with many existing pressure-responsive coatings. Its preparation necessitated preliminary formation of a porphyrin functionalized with two phenylphosphonic acid groups, which was obtained by synthesizing dipyrromethane and diethyl 4-formylphenylphosphonate and condensing these two precursors. The mixed phosphonate, a layered material assembled from ZrOCl2 · 8H2O, methylphosphonic acid, and the aforementioned porphyrin, was then prepared in refluxing HF. Solid-state 31P NMR spectra and powder X-ray diffraction patterns were acquired for the final product, its estimated interlayer spacing of 22.8 Å figuring prominently in analysis and discussion of the X-ray data.

No description available.

This thesis aims to improve the performance of latex-based pressure-sensitive adhesives (PSAs). PSA performance is usually evaluated by tack, peel strength and shear strength. Tack and peel strength characterize a PSA’s bonding strength to a substrate while shear strength reflects a PSA’s capability to resist shear deformation. In general, increasing shear strength leads to a decrease in tack and peel strength. While there are several commercial PSA synthesis methods, the two most important methods consist of either solvent-based or latex-based techniques. While latex-based PSAs are more environmentally compliant than solvent-based PSAs, they tend to have much lower shear strength, at similar tack and peel strength levels. Therefore, the goal in this thesis was to greatly improve the shear strength of latex-based PSAs at little to no sacrifice to tack and peel strength. In this study, controlling the polymer microstructure of latexes or their corresponding PSA films was used as the main method for improving the PSA performance. The research was sub-divided into four parts. First, the influence of chain transfer agent (CTA) and cross-linker on latex polymer microstructure was studied via seeded semi-batch emulsion polymerization of butyl acrylate (BA) and methyl methacrylate (MMA). Three techniques were used to produce the latexes: (1) adding CTA only, (2) adding cross-linker only, and (3) adding both CTA and cross-linker. It was found that using CTA and cross-linker simultaneously allows one to expand the range of latex microstructural possibilities. For example, latexes with similar gel contents but different Mc (molecular weight between cross-links) and Mw (molecular weight of sol polymers) could be produced if CTA and cross-linker concentration are both increased. However, for the corresponding PSAs with similar gel contents, the relationship between their polymer microstructure and performance was difficult to establish as almost all of the medium and high gel content PSAs showed very low tack and peel strength as well as extremely large shear strength readings. In the second part of this thesis, in order to improve the tack and peel strength of medium and high gel content PSAs, the monomer composition and emulsifier concentration were varied. It was found that changing the monomer mixture from BA/MMA to BA/acrylic acid (AA)/2-hydroxyethyl methacrylate (HEMA) while simultaneously decreasing emulsifier concentration dramatically improved the corresponding PSAs’ shear strength as well as tack and peel strength. The addition of polar groups to the PSA increased its cohesive strength due to the presence of strong hydrogen bonding; meanwhile, PSA films’ surface tension increased. In the third part, two series of BA/AA/HEMA latexes were generated by varying the amounts of CTA either in the absence or presence of cross-linker. The latexes produced in the absence of cross-linker exhibited significantly larger Mc and Mw compared to their counterparts with similar gel contents prepared with cross-linker. The PSAs with the larger Mc and Mw showed much larger shear strengths due to improved entanglements between the polymer chains. In the final part of the thesis, the performance of the BA/AA/HEMA PSAs was further improved by post-heating. Compared with original latex-based PSAs with similar gel contents, heat-treated PSAs showed not only significantly improved shear strengths, but also much larger tack and peel strengths. The different shear strengths were related to the PSAs’ gel structures, which were discrete in the original PSAs but continuous in the heat-treated PSAs. The improved tack and peel strengths were related to the PSA films’ surface smoothness. During the post-heating process, the PSA polymer flowed, resulting in much smoother surfaces than the original PSA films. In addition, the effect of post-heating was related to the polymer microstructure of the untreated PSAs. Decreasing the amount of very small or very big polymers or simultaneously increasing Mc and Mw could lead to post-treated PSAs with significantly better performance. Moreover, it was found that by optimizing the polymer microstructure of the original latex-based PSAs, it was possible to obtain a treated PSA with similar or even better performance than a solvent-based PSA with similar polymer microstructure. Our original objective was surpassed: in two cases, not only was shear strength greatly improved, but so were tack and peel strength due to the simultaneous modification of PSA bulk and surface properties.

This thesis aims to improve the performance of latex-based pressure-sensitive adhesives (PSAs). PSA performance is usually evaluated by tack, peel strength and shear strength. Tack and peel strength characterize a PSA’s bonding strength to a substrate while shear strength reflects a PSA’s capability to resist shear deformation. In general, increasing shear strength leads to a decrease in tack and peel strength. While there are several commercial PSA synthesis methods, the two most important methods consist of either solvent-based or latex-based techniques. While latex-based PSAs are more environmentally compliant than solvent-based PSAs, they tend to have much lower shear strength, at similar tack and peel strength levels. Therefore, the goal in this thesis was to greatly improve the shear strength of latex-based PSAs at little to no sacrifice to tack and peel strength. In this study, controlling the polymer microstructure of latexes or their corresponding PSA films was used as the main method for improving the PSA performance. The research was sub-divided into four parts. First, the influence of chain transfer agent (CTA) and cross-linker on latex polymer microstructure was studied via seeded semi-batch emulsion polymerization of butyl acrylate (BA) and methyl methacrylate (MMA). Three techniques were used to produce the latexes: (1) adding CTA only, (2) adding cross-linker only, and (3) adding both CTA and cross-linker. It was found that using CTA and cross-linker simultaneously allows one to expand the range of latex microstructural possibilities. For example, latexes with similar gel contents but different Mc (molecular weight between cross-links) and Mw (molecular weight of sol polymers) could be produced if CTA and cross-linker concentration are both increased. However, for the corresponding PSAs with similar gel contents, the relationship between their polymer microstructure and performance was difficult to establish as almost all of the medium and high gel content PSAs showed very low tack and peel strength as well as extremely large shear strength readings. In the second part of this thesis, in order to improve the tack and peel strength of medium and high gel content PSAs, the monomer composition and emulsifier concentration were varied. It was found that changing the monomer mixture from BA/MMA to BA/acrylic acid (AA)/2-hydroxyethyl methacrylate (HEMA) while simultaneously decreasing emulsifier concentration dramatically improved the corresponding PSAs’ shear strength as well as tack and peel strength. The addition of polar groups to the PSA increased its cohesive strength due to the presence of strong hydrogen bonding; meanwhile, PSA films’ surface tension increased. In the third part, two series of BA/AA/HEMA latexes were generated by varying the amounts of CTA either in the absence or presence of cross-linker. The latexes produced in the absence of cross-linker exhibited significantly larger Mc and Mw compared to their counterparts with similar gel contents prepared with cross-linker. The PSAs with the larger Mc and Mw showed much larger shear strengths due to improved entanglements between the polymer chains. In the final part of the thesis, the performance of the BA/AA/HEMA PSAs was further improved by post-heating. Compared with original latex-based PSAs with similar gel contents, heat-treated PSAs showed not only significantly improved shear strengths, but also much larger tack and peel strengths. The different shear strengths were related to the PSAs’ gel structures, which were discrete in the original PSAs but continuous in the heat-treated PSAs. The improved tack and peel strengths were related to the PSA films’ surface smoothness. During the post-heating process, the PSA polymer flowed, resulting in much smoother surfaces than the original PSA films. In addition, the effect of post-heating was related to the polymer microstructure of the untreated PSAs. Decreasing the amount of very small or very big polymers or simultaneously increasing Mc and Mw could lead to post-treated PSAs with significantly better performance. Moreover, it was found that by optimizing the polymer microstructure of the original latex-based PSAs, it was possible to obtain a treated PSA with similar or even better performance than a solvent-based PSA with similar polymer microstructure. Our original objective was surpassed: in two cases, not only was shear strength greatly improved, but so were tack and peel strength due to the simultaneous modification of PSA bulk and surface properties.

This thesis aims to improve the performance of latex-based pressure-sensitive adhesives (PSAs). PSA performance is usually evaluated by tack, peel strength and shear strength. Tack and peel strength characterize a PSA’s bonding strength to a substrate while shear strength reflects a PSA’s capability to resist shear deformation. In general, increasing shear strength leads to a decrease in tack and peel strength. While there are several commercial PSA synthesis methods, the two most important methods consist of either solvent-based or latex-based techniques. While latex-based PSAs are more environmentally compliant than solvent-based PSAs, they tend to have much lower shear strength, at similar tack and peel strength levels. Therefore, the goal in this thesis was to greatly improve the shear strength of latex-based PSAs at little to no sacrifice to tack and peel strength. In this study, controlling the polymer microstructure of latexes or their corresponding PSA films was used as the main method for improving the PSA performance. The research was sub-divided into four parts. First, the influence of chain transfer agent (CTA) and cross-linker on latex polymer microstructure was studied via seeded semi-batch emulsion polymerization of butyl acrylate (BA) and methyl methacrylate (MMA). Three techniques were used to produce the latexes: (1) adding CTA only, (2) adding cross-linker only, and (3) adding both CTA and cross-linker. It was found that using CTA and cross-linker simultaneously allows one to expand the range of latex microstructural possibilities. For example, latexes with similar gel contents but different Mc (molecular weight between cross-links) and Mw (molecular weight of sol polymers) could be produced if CTA and cross-linker concentration are both increased. However, for the corresponding PSAs with similar gel contents, the relationship between their polymer microstructure and performance was difficult to establish as almost all of the medium and high gel content PSAs showed very low tack and peel strength as well as extremely large shear strength readings. In the second part of this thesis, in order to improve the tack and peel strength of medium and high gel content PSAs, the monomer composition and emulsifier concentration were varied. It was found that changing the monomer mixture from BA/MMA to BA/acrylic acid (AA)/2-hydroxyethyl methacrylate (HEMA) while simultaneously decreasing emulsifier concentration dramatically improved the corresponding PSAs’ shear strength as well as tack and peel strength. The addition of polar groups to the PSA increased its cohesive strength due to the presence of strong hydrogen bonding; meanwhile, PSA films’ surface tension increased. In the third part, two series of BA/AA/HEMA latexes were generated by varying the amounts of CTA either in the absence or presence of cross-linker. The latexes produced in the absence of cross-linker exhibited significantly larger Mc and Mw compared to their counterparts with similar gel contents prepared with cross-linker. The PSAs with the larger Mc and Mw showed much larger shear strengths due to improved entanglements between the polymer chains. In the final part of the thesis, the performance of the BA/AA/HEMA PSAs was further improved by post-heating. Compared with original latex-based PSAs with similar gel contents, heat-treated PSAs showed not only significantly improved shear strengths, but also much larger tack and peel strengths. The different shear strengths were related to the PSAs’ gel structures, which were discrete in the original PSAs but continuous in the heat-treated PSAs. The improved tack and peel strengths were related to the PSA films’ surface smoothness. During the post-heating process, the PSA polymer flowed, resulting in much smoother surfaces than the original PSA films. In addition, the effect of post-heating was related to the polymer microstructure of the untreated PSAs. Decreasing the amount of very small or very big polymers or simultaneously increasing Mc and Mw could lead to post-treated PSAs with significantly better performance. Moreover, it was found that by optimizing the polymer microstructure of the original latex-based PSAs, it was possible to obtain a treated PSA with similar or even better performance than a solvent-based PSA with similar polymer microstructure. Our original objective was surpassed: in two cases, not only was shear strength greatly improved, but so were tack and peel strength due to the simultaneous modification of PSA bulk and surface properties.

In this study, the film-cooling effectiveness in different regions of gas turbine blades was investigated with various film hole/slot configurations and mainstream flow conditions. The study consisted of three parts: 1) turbine blade span film-cooling, 2) turbine platform film-cooling, and 3) blade tip film-cooling. Pressure sensitive paint (PSP) technique was used to get the conduction-free film-cooling effectiveness distribution. Film-cooling effectiveness is assessed in terms of cooling hole geometry, blowing ratio, freestream turbulence, and coolant-to-mainstream density ratio. Blade span film-cooling test shows that the compound angle shaped holes offer better film effectiveness than the axial shaped holes. Greater coolant-to-mainstream density ratio prevents coolant to lift-off. Higher freestream turbulence causes effectiveness to drop everywhere except in the region downstream of suction side. Results are also correlated with momentum flux, compound shaped hole has the greatest optimum momentum flux ratio, and then followed by axial shaped hole, compound cylindrical hole, and axial cylindrical hole. For platform purge flow cooling, the stator-rotor gap was simulated by a typical labyrinth-like seal. Two different film-cooling hole geometries, three blowing ratios and density ratios, and two freestream turbulence are examined. Results showed that the shaped holes present higher film-cooling effectiveness and wider film coverage than the cylindrical holes, particularly at higher blowing ratios. Moreover, the platform film-cooling effectiveness increases with density ratio but decreases with turbulence intensity. The blade tip study was performed in a blow-down flow loop. Results show that a blowing ratio of 2.0 is found to give best results on the tip floor. Lift-off of the coolant jet can be observed for the holes closer to the leading edge as blowing ratio increases from 1.5 to 2.0. A stator vane suction side heat transfer study was conducted in a partial annular cascade. The heat transfer coefficients were measured by using the transient liquid crystal technique. At X/L=0.15, a low heat transfer region where transition occurs. The heat transfer coefficients increase toward the trailing edge as flow accelerates; a spanwise variation can be found at neat tip and hub portions due to passage and horseshoe vortices.

Pressure sensitive adhesives (PSAs) are polymeric materials with versatile applications in industrial and consumer products such as protective films, product labels, masking tape, and sticky notes, to name a few applications. World demand for emulsion–based products is on the rise due to worldwide legislation on solvent emissions. In order to completely replace emulsion-based PSAs with their solvent-based counterpart, the property modification of emulsion-based PSAs is required. The use of nanomaterials to modify polymer properties is well established. The aim of this thesis was to use cellulose nanocrystals (CNCs) as property modifiers for emulsion-based PSAs. CNCs are recognized as a highly efficient reinforcement nanofiller. Owing to their environmentally friendly characteristics, low density, high aspect ratio, non-toxicity, and abundant availability, the application of CNCs in composite materials is gaining increasing attention. In this thesis, the inclusion of CNCs in emulsion-based PSAs was carried out through in situ emulsion polymerization and blending technique. To the best of our knowledge, there is limited information about the synthesis of CNC/PSAs nanocomposites via in situ emulsion polymerization and the evaluation of their mechanical performance. The addition of CNCs to the polymerization formulation caused latex instability due to the negatively charged surfaces of the CNCs. After numerous attempts to overcome the stability issues, a stable polymerization formulation and protocol were developed. CNC/PSAs were synthesized via in situ seeded-semi batch emulsion polymerization, which is a common commercial production pathway for PSAs. The mechanical performance of the resulting PSA nanocomposite films, namely, shear strength, tack, and peel strength, was evaluated at several CNC loadings. All three PSA adhesive properties were simultaneously enhanced with increasing CNC loading. The inclusion of CNCs into the films increased their hydrophilicity. Consequently, the PSA films’ improved wettability on a stainless steel substrate imparted greater tack and peel strength. The blending of the CNCs with a base latex also led to improved adhesive properties. However, the property modification through blending was not as effective as that for the CNC/PSA films synthesized via in situ emulsion polymerization. Thus, CNCs are safe nanomaterials that have been shown to provide remarkable property enhancement of emulsion-based PSA films at low loadings (1wt%).

After the end of the NASA space shuttle programme, there has been resurgence of interest in developing a single stage-to-orbit spacecraft. The key technology to realize this dream is the airbreathing scramjet engine. The scramjet concept has been around for decades, but much work is still needed in order to eliminate the remaining obstacles to develop a practical working prototype of the engine. Many such obstacles are related to the inlet which functions as the main compression unit for the engine. Typically, a high speed inlet is designed to function properly in a single flight condition. Such an inlet would experience adverse flow conditions related to various shock-shock interactions, viscous effects, shock-boundary layer interactions, and many other flow phenomena at off-design conditions. The traditional mechanism to mitigate the adverse flow conditions is by varying the inlet geometry at off-design conditions. There are still gaps in understanding the behaviour of inlets at off-design conditions and the effectiveness of variable geometry as inlet flow control. This is partly due to complex flow diagnostics setup, which limits the type, quantity and quality of information that can be extracted from the inlet flow. The first objective of this thesis was to develop a global inlet measurement system that can provide an abundance of information on inlet flow. The pressure sensitive paint method was employed together with other methods to provide comprehensive understanding on inlet flow characteristics. Calculation of Mach number at the isolator exit using the isolator sidewall pressure map was successfully demonstrated. The measurement of Mach number at the isolator exit has allowed for performance of the inlet to be calculated without the need for intrusive flow diagnostics tools used by previous researchers. The global measurement system was then employed to investigate the characteristics of the scramjet inlet operating at various off-design conditions. Complex shock structures were observed at the inlet cowl entrance as the angle-of-attack was increased. The relationship of flow quality and inlet performance was examined and discussed. General improvements on the inlet performance were obtained if the size of separation on the compression ramp was reduced. The inlet was also observed to perform poorly when compression shocks impinged on the inner cowl surface. Cowl deflections were demonstrated to be effective in controlling the internal flow of the inlet and improving its performance. An exploratory study on the role of micro-vortex generators to control boundary layer separation on scramjet inlets has been included as well. Strategies for optimizing an inlet at off-design conditions were analysed, and it was found that any variable geometry combination must maintain high throat-to-freestream Mach number ratio in order to preserve high inlet performance.

Orientador: Julio Roberto Bartoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T21:53:07Z (GMT). No. of bitstreams: 1 Zanin_AileenNicoleFowler_M.pdf: 11356850 bytes, checksum: cf01903240aa482d9b8d8f3559af3823 (MD5) Previous issue date: 2006 / Resumo: Adesivo Sensíveis à Pressão (PSA) são adesivos poliméricos usados principalmente em fitas e etiquetas. De modo geral, existem três tipos de adesivos PSA: a base de solvente, a base d'água e "hot melt". Os adesivos a base de solvente apresentam algumas limitações como flamabilidade e toxicidade, mas ainda são amplamente usados, devido às propriedades finais que apresentam, como boa adesividade a substratos polares c boa adesão com alguns plásticos. Geralmente, os compostos poliméricos para PSA utilizam cargas minerais devido à redução de custo e às propriedades finais que os PSA podem apresentar, como propriedades dielétricas, resistência à umidade e tensão na ruptura. Por outro lado, nanocompósitos estão mostrando grandes vantagens em várias aplicações poliméricas, melhorando suas propriedades térmicas, mecânicas e retardância à chama. Adesivos PSA nanocompósitos a base de solvente foram preparados pelo processo de esfoliação-solução de compostos a base de borracha natural e argilas organicamente modificadas. Um planejamento fatorial de experimentos, 22 com replicata, foi utilizado para verificar a influência dos fatores da composição: concentração e tipos de argilas modificadas, nas propriedades físicas dos adesivos. Um composto adesivo de referencia (PSA convencional) foi também preparado utilizando CaCOH3, carga de uso comum nessas formulações. Os adesivos foram caracterizados através das suas propriedades adesivas (coesão ou "shear", adesão ao aço ou "peel" ,tlato à superfície ou "tack") gel e resistência à propagação de chama. A maioria dessas propriedades apresentou significância estatística em ao menos um dos fatores de composição estudados, tipo ou concentração de nanoargila. Os ensaios de resistência á propagação de chama mostraram melhoria nas propriedades de resistência à propagação da chama em todos os adesivos com argilas modificadas, comparados ao composto de referência. Análises TGA indicaram o mesmo comportamento de variação de massa em função da temperatura para lodos os adesivos. As análises DMTA dos adesivos mostraram diferenças entre os dois tipos de argilas modificadas quanto às suas Tg. Nas análises XRD dos adesivos não foram identificados picos de difração característicos das argilas, talvez devido à diluição das amostras ou até à desejada esfoliação. Nas análises de SEM dos compostos adesivos observou-se uma tênue forma lamelar devido às argilas e as análises EDS dos compostos indicaram a presença de Si e Al, constituintes da argila modificada / Abstract: Pressure sensitive adhesives (PSA) are polymeric adhesives used for mainly in tapes and labels. Usually, there are 3 types of PSA: solvent based, water based and hot melt. Solvent based adhesives have few limitations, like flammability and toxicity, but they are still often used, due to their properties as good adhesion to polar substrates and good bonding with some plastics. The compounds for pressure sensitive adhesives, in general, use fillers due to cost reduction and properties they can give, like dielectric properties, water resistance and tensile strength. On the other side, nanocomposites are showing great advantages on several polymers applications improving thermal resistance, flame retardancy and mechanical properties. Nanocomposites for solvent-based adhesives were prepared by an exfoliation-solution process of natural rubber and organically modified clay compounds. A Design of Experiment (DOE). 22 with replication, was used to verify the influence of compounding factors; concentration and grades of nanoclays.A control adhesive compound was prepared using CaCO3, very common filler for adhesive fonnulations. The PSA were characterized by their adhesive properties (cohesion or shear, adhesion to steel or peel test, tack), gel and flammability. Almost all these properties showed statistical significance at least for one of the compounding factors, grade or concentration of nanociay. The flammability tests showed an improvement on the flame retardancy properties for all the nanoclays adhesives compared to the control compound. TGA analyses showed the same pattern of mass reduction as a function of temperature for all the adhesives. DMTA showed differences between the 2 kinds of nanoclays regarding Tg. XRD analyses did not show any diffraction peak related to the clays, likely due to the diluted samples or even to an exfoliation. SEM analyses showed a slightly lamellar pattern of clays and EDS analyses of the compounds confirmed the presence of Si and Al, elements of the nanoclays / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química