Dissertations / Theses on the topic 'Physico-Mechanical and hygro-Thermal properties'
To see the other types of publications on this topic, follow the link: Physico-Mechanical and hygro-Thermal properties.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Physico-Mechanical and hygro-Thermal properties.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Se, Golpayegani Motamedi Aida. "Caractérisation du bois de Mûrier blanc (Morus alba L.) en référence à son utilisation dans les luths Iraniens." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20157.
Abstract:
L'objectif est de mieux connaître les diverses propriétés (physico-mécaniques, biologiques et chimiques) du bois de Mûrier blanc (Morus alba L.), en tant que matériau éminemment utilisé dans la fabrication de luths Iraniens. La différence de caractéristiques vibratoires de cette espèce a été mesurée en fonction de la présence d'extractibles, mais aussi pour trois traitements artisanaux qui ont été adaptés à l'échelle du laboratoire.Le bois Mûrier blanc est caractérisé par un module spécifique modéré, un amortissement plus bas que prévu et une anisotropie faible entre ses trois axes. Il est précisé que cette espèce ne peut pas être classifiée avec les mêmes normes que les autres bois utilisés pour les instruments classiques Européens. En utilisant les deux extractions indépendantes et successives, il est révélé que l'amortissement est régi par deux types d'extraits, certains l'abaissent et certains l'augmentent. Ces composés ne sont pas tous extractibles par les mêmes solvants. L'immersion de longue durée dans une eau à température ambiante ne modifie pas les propriétés mécaniques de l'espèce, toutefois, elle peut laisser le bois avec des défauts irréversibles. Un court traitement à l'eau chaude (70°C) entraîne l'augmentation de l'amortissement et la diminution du module spécifique. Dans ce dernier cas, des modifications sont presque progressives avec le temps.Le bois de Mûrier blanc semble être « très durable » par rapport à une attaque fongique, même dans des conditions extrêmes. Le délavage dans l'eau n'a pas d'effets sur la résistance de cette espèce contre basidiomycètes. Ce bois est classé « moyennement durable » contre l'attaque des termites et devient sensible après le délavage. Ses extractibles ont donc des effets toxique sur les termites. Les phénols, acides gras, stérols, hydrocarbures supérieurs, et composés aromatiques sont les composés présents dans les extraits de cette espèce. Le résorcinol, composé prédominant trouvé dans l'espèce, a été récemment rapporté comme la cause de plusieurs problèmes de santé, ce qui est aujourd'hui observé chez les artisans IraniensThis work aims at studying the several divers properties (Physico-mechanical, biological and chemical) of white Mulberry (Morus alba L.), as the leading material used in fabrication of Iranian lutes. The vibrational characteristic of this species is measured in relation with secondary metabolites (extractives) as well as three artisanal hygro-thermal treatments adapted to laboratory scale.White Mulberry wood is characterized with a moderate specific modulus, less than expected damping and a low anisotropy between three directions. It is specified that this species cannot be described with the same standards as other woods used in European classical instruments. Using independent and successive extractions reveal that two types of extraneous compounds govern the damping in this wood, some raising it, when the rest have a decreasing effect. These compounds are not all extractable by the same solvents.Long time immersion in water at ambient temperature hardly changes mechanical properties of the species, however, it can leave wood with irreversible defects. Hot water treatment at 70°C results for damping and moduli to be increased and decreased respectively. These changes are time related. Several mild desorption and adsorption cycles, seem to reduce damping without greatly endangering the moduli. White Mulberry wood is found to be very durable towards fungi, even in extreme conditions. Water leaching seems to be affectless on this species resistance towards basidiomycetes. This wood is rated moderately durable towards termites and becomes sensible after water leaching. Extractives seem to play important role in this wood natural resistance, as they are found to have toxic effect on termites. Resorcinol, a phenol, is the leading compound in the extractives of white Mulberry. Fatty acids, sterols, higher hydrocarbons, and aromatic compounds are also found as the constituents of secondary metabolites. Resorcinol is documented to cause irritations close to what is normally experienced by the fabricants working with white Mulberry for a long time
2
Daher, Suzanne. "Optimisation de la formulation d'un béton de chanvre : effet des interactions physico-chimiques entre les particules végétales et le liant." Electronic Thesis or Diss., Amiens, 2022. http://www.theses.fr/2022AMIE0041.
Abstract:
Le béton de chanvre est l'un des matériaux de construction biosourcés le plus en vogue en France. Il est souvent utilisé comme matériau de remplissage et/ou d'isolation, dans un système éco-constructif. Compte tenu de sa forte porosité, ce béton présente des performances thermiques et hygriques particulièrement intéressantes. Toutefois, alors que son niveau d'isolation thermique s'améliore lorsqu'on diminue sa densité, ce béton de chanvre voit parallèlement ses propriétés mécaniques diminuer. C'est la raison pour laquelle, il est nécessaire d'optimiser sa formulation, afin d'obtenir le meilleur compromis entre ses performances mécaniques, hygriques et thermiques, selon le domaine d'emploi (porteur et/ou isolant). La première piste d'optimisation envisagée consiste à faire varier le taux de granulats végétaux dans la composition du béton, mais aussi la nature et la quantité de liant utilisé. Le travail de cette thèse a pour objectif l'étude des propriétés mécaniques, thermiques et hygriques d'un béton de chanvre en fonction de sa formulation. Dans ce mémoire, on s'intéresse à la faisabilité de matériaux de construction légers à base de particules de chanvre et d'un liant à base de chaux, qui présentent de bonnes performances mécaniques. L'objectif principal ici est de réduire la concentration des ions Ca2+ libres responsables de la dégradation des particules végétales par minéralisation, et qui, par conséquent, induisent la perte de performance mécanique du matériau composite final. Pour y parvenir, une fraction du liant de base a été remplacée par du métakaolin qui interagit avec ces ions Ca2+ suivant une réaction pouzzolanique, afin d'empêcher leur migration vers les particules végétale. Dans un premier temps, nous avons étudié l'influence de différents pourcentages de métakaolin sur les liants témoins à base de chaux: chaux NHL5 et chaux préformulée Tradical PF70. Une étude préliminaire de caractérisation mécanique, en compression et en flexion, a permis suivant une approche "performantielle" de définir une formulation optimale des liants utilisés pour la fabrication des bétons étudiés. Ainsi, les matériaux composites finis sont testés pour différents pourcentages en volume (2V et 3V) de particules de chanvre. Les résultats de la caractérisation des propriétés physico-mécaniques de ces matériaux sont présentés et argumentés. Il en ressort une relation étroite entre la teneur en métakaolin et les propriétés physico-mécaniques du béton de chanvre, qui résulte de la réaction pouzzolanique. Des analyses microscopiques au MEB couplées à l'EDX ont montré une diminution de la zone de transition à l'interface particules de chanvre-liant, mais aussi une faible migration des ions Ca2+ responsables de la minéralisation des particules végétales. Puis, nous avons comparé les performances hygro-thermiques des bétons de chanvre formulés comprenant respectivement 2 volumes et 3 volumes de particules végétales pour un volume de liant, sans ou avec 20% de métakaolin, pourcentage optimal défini précédemment. Cette étude est particulièrement utile pour établir les proportions adéquates d'adjuvants à utiliser dans les bétons destinés aux travaux de rénovation ou aux constructions neuves. D'une manière générale et en fonction de la formulation, on obtient un matériau bon, voire excellent régulateur de l'humidité ambiante, avec des performances thermiques intéressantes pour l'isolation des bâtiments. Ce travail de caractérisation complète les nombreux travaux déjà réalisés sur les bétons biosourcés avec différents types de végétaux, et doit permettre d'alimenter les bases de données indispensables pour la simulation du comportement d'une paroi ou de l'enveloppe d'un bâtiment sous différents climats et garantir le confort des occupantsHemp concrete is one of the most popular bio-based building materials in France. It is often used as a filling and / or insulation material, in an eco-construction system. Given its high porosity, this concrete has particularly advantageous thermal and hygric performance. However, the lighter this hemp concrete, the higher its level of thermal insulation, while its mechanical properties decrease. This is why it is necessary to optimize its formulation, in order to obtain the best compromise between its mechanical, hygric and thermal performance, depending on the field of use (carrier and / or insulator). The first optimization approach considered consists in varying the rate of plant aggregates in the composition of the concrete, but also the nature and quantity of binder used. The objective of this thesis is to study the mechanical, thermal and hygric properties of a hemp concrete according to its formulation. In this thesis, we are interested in the feasibility of lightweight building materials based on hemp particles and a lime-based binder, which present good mechanical performances. The main objective is to overcome the migration process of free Ca2+ to the lumen of hemp particles that are responsible for their degradation and which, consequently, induce the loss of mechanical performance of the final composite material. To achieve this, a fraction of the base binder is replaced by metakaolin. First, we studied the influence of different percentages of metakaolin on the carbonation of two lime-based control mortars: NHL5 lime and Tradical PF70 pre-formulated lime. Then, we measured their mechanical resistances in compression and flexion in order to define an optimal formulation. Thus, the finished composite materials are tested for different volume percentages (2v and 3v) of hemp particles. The results of the characterization of the physico-mechanical properties of the specimens are presented and argued. A close relationship between the metakaolin content and the physico-mechanical properties of the hemp concrete has been observed, due to the additional hydration products derived from pozzolanic reaction mechanism. The MEB and EDX analyses have shown the enhancement of hemp particles-binder Interfacial Zone Transition, while the pozzolanic reaction leads to reduce the migration process of free Ca2+ to lumen of vegetable particles thus reducing their mineralization. Then, we compared the hygro-thermal performances of hemp concretes formulated with respectively 2 volumes and 3 volumes of plant particles for one volume of binder, without or with 20% metakaolin, the optimal percentage defined previously. This study is particularly useful to establish the adequate proportions of admixtures to be used in concretes intended for renovation works or new constructions. Generally speaking, and depending on the formulation, we obtain a material that is a good or even excellent regulator of ambient humidity, with interesting thermal performances for the insulation of buildings. This characterization work completes the many works already carried out on biobased concrete with different types of plants, and should make it possible to feed the databases essential for the simulation of the behavior of a wall or of the envelope of a building under different climates and guarantee the comfort of the occupants
3
Saetung, Anuwat. "Preparation of polyurethane foams from hydroxytelechelic oligoisoprenes obtained by controlled degradation of natural rubber : study of their physico-mechanical, thermal, and acoustic properties." Le Mans, 2009. http://cyberdoc.univ-lemans.fr/theses/2009/2009LEMA1006.pdf.
Abstract:
Les mousses de polyuréthane constituent les matériaux polyuréthane les plus largement étudiés et utilisés pour de nombreuses applications telles que l'ameublement, l'automobile, l'isolation thermique et phonique. Les composés hydroxylés couramment utilisés pour la production des mousses de polyuréthane sont des produits issus de la pétrochimie (polyols à base de polyesters ou de polyéthers). Ces produits ont le désavantage d'être issus de sources non renouvelables pouvant provoquer des pollutions de l'environnement et risquant de se tarir à court terme. Le caoutchouc naturel constitue un matériau de base pour la synthèse des polyuréthanes particulièrement intéressant en tant que matériau issu d'une source renouvelable abondante, avec des propriétés mécaniques intéressantes et une structure chimique facilement modifiable. Dans ce travail, un nouveau caoutchouc naturel hydroxytéléchélique (HTNR) de fonctionnalité 2 a été obtenu par l'intermédiaire de réactions contrôlées d'époxydation et de clivage du caoutchouc naturel, suivies d'une réduction sélective des oligoisoprènes carbonyltéléchéliques obtenus. Ces HTNR de différentes masses molaires (1000-3400 g mol-1), ont été obtenus de façon reproductible et avec des rendements élevés. Des modifications chimiques de ces HTNR ont été effectuées par époxydation (10-35% EHTNR), hydrogénation et réactions d'ouverture des oxiranes. Les différentes microstructures de ces oligomères ont été caractérisées par FT-IR, RMN, SEC et MALDI-TOF MS. Leurs propriétés thermiques ont été déterminées par TGA et DSC. Des mousses de polyuréthane ont été préparée à partir d'HTNR et d'EHTNR de différentes masses molaires et de différents taux d'époxydation en une étape. Les structures chimiques, les caractéristiques physiques des mousses, leurs propriétés mécaniques, thermiques et acoustiques ont été déterminées et comparée à celles des mousses de polyuréthane analogues synthétisées à partir de polyols commerciaux. Les mousses de polyur‚thane à base d'HTNR ont une structure de cellules ouvertes de dimensions 0,38 à 0,47 mm. Les propriétés mécaniques varient selon les masses molaires des oligomères hydroxytéléchéliques : les mousses de polyuréthane issues d'HTNR1000 présentent des forces d'élongation et de compression supérieures à celles de leurs homologues commerciaux, mais l'élongation à la rupture est plus faible. Les mousses à base d'HTNR3400 présentent les meilleures propriétés élastiques. Pour la série des mousses à base d'EHTNR, les forces d'élongation et de compression augmentent avec l'augmentation des taux d'époxydation. Les mêmes résultats sont observés avec des quantités croissantes de butane-1,4-diol. Pour ce qui concerne les propriétés thermiques, les mousses de polyuréthane à base d'HTNR présentent une meilleure flexibilité à basse température que leurs homologues à base de polyols commerciaux. De plus, elles présentent d'excellentes propriétés d'absorption acoustiquePolyurethane foam (PUF) is the largest of polyurethane materials widely studied and used in many applications such as furniture, automobile, insulation, acoustic absorber. Hydroxyl compounds currently used in the production of PUF are petrochemical products (polyester and polyether polyols). However, they have some disadvantages as they are non-renewable resources, they may cause environmental pollution, and they tend to be exhausted in the near future. Natural rubber (NR) is an interesting choice to use as a starting material in PUF synthesis, due to the fact that they are renewable source, abundant polymer and they have good mechanical properties and are easy to chemically modify. In this work, a new hydroxytelechelic natural rubber (HTNR) having a hydroxyl functionality of 2 was successfully performed via controlled epoxidation and cleavage of natural rubber, following by a selective reduction reaction of the obtained carbonyltelechelic oligoisoprenes. These HTNR with different molecula r weights (1000-3400 g mol-1) were reproducible obtained with high yields. Chemical modifications on HTNR were performed by epoxidation (10-35%, EHTNR), hydrogenation and oxirane opening reactions. The different microstructures of these oligomers were evidenced by the characterization techniques FT-IR, NMR, SEC and MALDI-TOF MS. Their thermal properties were also investigated by TGA and DSC. Polyurethane foams were successfully prepared from a renewable source, HTNR with different molecular weights and EHTNR having a variation of epoxide content, by one shot technique. The chemical structure and cell structure as well as physico-mechanical, thermal and acoustic properties were characterized to compare with commercial polyol analogues. It was investigated that the obtained HTNR based foams are open cell structures and have cell dimensions between 0. 38 and 0. 47 mm. Concerning, physico-mechanical properties, HTNR1000 based foam exhibits higher tensile and compressive strengths than commercial polyol analogue, but the elongation at break is lower. However, HTNR3400 based foam shows the best for elastic properties. In series of EHTNR based foams, the tensile and compressive strengths give a trendy increasing with increasing the epoxide content. Same results were observed with increasing amount of 1,4-butanediol. For thermal properties, HTNR based foams show better low temperature flexibility than that based on commercial polyol. Moreover, HTNR based polyurethane foams give an excellent acoustic absorber
4
Apreutesei, Mihai. "Temperature impact on thermal evolution of advanced PVD ceramic and metallic glass thin films : Physico-chemical and microstructural analysis." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0009/document.
Abstract:
Ces dernières années, les exigences de l'industrie dans le développement de nouveaux matériaux fonctionnels en mesure de résister aux conditions difficiles pendant l'opération d'usinage sont en constante augmentation. Les chercheurs doivent donc trouver de nouvelles solutions pour répondre aux besoins industriels de plus en plus sévères. L’utilisation de revêtement protecteur à la surface de l’outil de coupe est une solution très efficace. Des nouveaux matériaux architecturés sont étudiés pour leurs propriétés mécaniques, physiques et chimiques uniques assurant une résistance aux dégradations de surface dues à la corrosion, l'usure, le frottement; en particulier lorsque ces outils sont utilisés dans des environnements hostiles. Dans le cadre de cette thèse de doctorat, l'influence de la température sur la stabilité structurale de deux types de films minces déposés par PVD a été étudiée. Des films céramiques et de verre métallique ont été envisagés. Afin de préparer et optimiser ces films, le projet s’est axé sur l'étude de l'influence des conditions de dépôt sur les caractéristiques de croissance du film: composition chimique, structure, morphologie, puis sur les changements ultérieurs des principales propriétés des films minces, à savoir la résistance à l’oxydation et à la cristallisation lors de leur utilisation à hautes températures. Une démarche multi-échelle a été développée pour caractériser au mieux les couches. La première partie du travail est liée aux revêtements céramiques à base de CrN pour donner de nouvelles fonctionnalités et améliorer la surface des outils de coupe dans le but essentiel d'accroître leur durée de vie. La seconde partie du manuscrit est dédiée aux films minces de verres métalliques de Zr-Cu préparés par un procédé de co-pulvérisation magnétron PVD. Le but de cette partie consiste en l’étude de la relation entre la structure amorphe de ces films et leurs propriétés mécaniques. La conservation du caractère amorphe de ces films en température présente également un caractère essentiel. Les verres métalliques ont récemment attiré un fort intérêt car ils présentent des propriétés mécaniques intéressantes à température ambiante. Ils présentent, de ce fait, un grand potentiel pour des applications d'ingénierie en raison de leurs caractéristiques mécaniques et physico-chimiques uniques (haute limite élastique, résistance à la corrosion ...). Pour relier les propriétés mécaniques des couches à l’évolution de leurs microstructures, une partie importante de ce travail a porté sur l’observation de l’évolution de la couche au cours du chauffage au moyen de techniques de caractérisation in situ. Les films minces proposés au cours de ce travail peuvent être envisagées pour un large gamme d’application dans l’ingénierie de surface pour protéger les surfaces et améliorer la durée de vie des matériauxIn the recent years the industrial requirements to develop new functional materials able to overcome the severe conditions during machining operation are continuously increasing. Researchers then must find novel solutions to respond to their severe industrial requirements. To coat the tool surface with advanced coatings is the most efficient solution. New nanostructured materials may nowadays exhibit unique mechanical, physical and chemical properties ensuring notable degradation resistance where the surface protection of materials against corrosion, wear, friction or oxidation is a key issue, particularly when operating in hostile environments. Within the scope of this Ph.D. thesis the influence of the temperature on the structural stability of two different PVD ceramic and metallic glass thin films is proposed. The main goal consists in the development of two distinct classes of thin films, with a wide range of properties. In order to prepare these films, the project will be focused on the study on the influence of PVD deposition conditions in the particular film’s growth characteristics: chemical composition, structure, morphology and the subsequent changes in the main properties of the thin films, namely oxidation and crystallization resistance, especially. For that purpose we adopted the multiscale approach. The first part is related to the ceramic CrN-based coatings to give new functionalities and improve the tools’ surface with the primary aim to increase their lifetime. Secondly, new protective materials able to better protect the exposed surfaces against high temperature oxidation have been proposed, namely CrAlN and CrAlYN coatings as will be evidenced in this manuscript. The second part of the manuscript is dedicated to the innovative Zr-Cu thin films metallic glasses prepared by a PVD magnetron co-sputtering method with the objective to investigate the amorphization ability and their structural properties. Their excellent properties at room temperature have recently attracted attention as a new class of materials with great potential for engineering applications due to unique mechanical and physico-chemical characteristics (high elastic strain limit, corrosion resistance…). Finally, an important approach during the course of this thesis was the real time observation of the structure and surface modifications during heating by means of in situ methods. The thin films proposed during the course of the work could be straightforward used as surface engineering solutions to protect and extend the lifetime of the materials and components
5
Sani, Rababe. "Étude des transformations microstructurales de mélanges argile/Combustibles Solides de Récupération (CSR) lors de la cuisson : relations entre propriétés physico-chimiques, mécaniques et thermiques." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2018. http://www.theses.fr/2018EMAC0005/document.
Abstract:
La valorisation des co-produits riches en matières organiques et inorganiques comme additifs dans des formulations à base d’argile peut améliorer à la fois les performances mécaniques et thermiques des produits de terre cuite, de même que le bilan énergétique des procédés de fabrication de ces matériaux. Cette étude a porté sur l’incorporation de combustibles solides de récupération (CSR) dans un mélange de fabrication des produits de terre cuite pour le génie civil en étroite collaboration avec l’entreprise TERREAL dans le cadre du projet LabCom RESPECTc financé par l’ANR.Premièrement, deux CSR ont été sélectionnés et utilisés comme additifs pour améliorer les produits issus des deux gisements de mélange argileux nommés ML et MC de chez TERREAL. L’influence de la nature, du taux d’incorporation des CSR, de la granulométrie des CSR et de la nature de la matrice argileuse sur les propriétés physico-chimiques, mécaniques et thermiques des mélanges argileux/CSR a été étudiée entre 30°C et 1100°C. Dans tous les cas, l’ajout de CSR a permis d’améliorer le caractère isolant des produits de terre cuite, en diminuant leur conductivité thermique. L’ajout de CSR a aussi permis d’améliorer les propriétés mécaniques des produits, en fonction du type et du taux de CSR ajouté, du taux et de la nature (forme, taille et distribution) de la porosité créée. L’étude a démontré que les interactions entre les minéraux argileux et les éléments inorganiques des CSR avaient un impact important sur les propriétés mécaniques et thermiques. Les résultats ont montré que l’ajout de 4% en masse du CSR15-1 contenant un taux de cendres de 65,7% en masse a conduit à une augmentation de la résistance mécanique du matériau à base de la matrice argileuse ML de l’ordre de 32%. Ensuite, un modèle cinétique du frittage basé sur les variations dimensionnelles des matériaux entre 650°C et 1000°C a été développé à partir de l’analyse thermomécanique (ATM) des mélanges (avec ou sans CSR). L’objectif a été de mieux comprendre les mécanismes du frittage mis en jeu. Le modèle développé a montré une bonne adéquation avec les données expérimentales. Les résultats ont montré que l’étape du frittage thermique de ces mélanges se fait en présence d’une phase liquide et que l’ajout de CSR a permis d’accélérer la densification des matériaux. Cela a conduit à une diminution de la température usuelle de cuisson des produits de terre cuite permettant ainsi un gain énergétique non négligeable. Finalement, une étude environnementale a été réalisée lors de la cuisson des mélanges argileux/CSR. Cette étude a particulièrement été focalisée sur la contribution de CSR au bilan énergétique et à l’impact des émissions des gaz critiques tels que le CO2, le CO et l’HCl. Les résultats ont montré que les émissions de CO2 et de CO lors de la cuisson des mélanges argileux/CSR ont augmenté en raison de la décomposition thermique de la matière organique des CSR et que moins de 50% en masse du chlore a été transformé en HCl (18-31 ppm). Le bilan énergétique effectué a montré que l’ajout de CSR au sein des matrices argileuses ML ou MC compense une part non négligeable du gaz naturel usuellement utilisé comme combustible au cours de la cuisson de ces matériaux. Cela s’est traduit par une économie d’énergie thermique et une réduction des émissions de CO2 provenant de la décarbonatation de la matrice argileuseThe valorization of co-products rich in organic and inorganic materials as additives in formulations based on clay matrix can improve both the mechanical and thermal performances of ceramic materials as well as the energy balance of the manufacturing processes of these products. This study focused on the incorporation of Solid Recovered Fuels (SRF) into the clay ceramics for civil engineering in close collaboration with TERREAL as part of the ANR funded LabCom RESPECTc project. Firstly, two SRF were selected and used as additives to improve the properties of ceramic materials from to clay mixture deposits named ML and MC from TERREAL. The influence of the nature, the amount of SRF, the grain size of SRF and the nature of clay matrix on the physico-chemical, mechanical and thermal properties of the clay/SRF mixtures were studied between 30°C and 1100°C. In all cases, the addition of SRF into the clay mixture (ML or MC) has enhanced the insulating nature of the ceramic materials by reducing their thermal conductivity. The addition of SRF has also improved the mechanical properties of the ceramic materials, depending on the nature and the amount of SRF added, the rate and the nature (shape, size and distribution) of the porosity created. The study demonstrated that interactions between clay minerals and inorganic elements of SRF have a significant effect on mechanical and thermal properties. The results showed that the addition of 4 wt.% of SRF15-1 containing an ash content of 65.7 wt.% into clay matrix ML led to increase the mechanical strength of the material based on the clay matrix ML of the order of 32%. Then, a kinetic model of thermal sintering based on the dimensional variations of ceramic materials between 650°C and 1000°C was developed from thermomechanical analysis (TMA) of the clay mixtures (with or without SRF). The main objective is to better understand the mechanism of the thermal sintering involved. The model developed showed a good adequacy with the experimental data. The results showed that the thermal sintering step of these mixtures is carried out by the presence of a liquid phase and that the addition of SRF has accelerated the densification of ceramic materials. This has led to decrease the usual firing temperature of ceramic materials, allowing a significant energy savings. Finally, an environmental assessment was carried out during the firing of clay/SRF mixtures. This study was particularly focused on the contribution of SRF to the energy balance and impact of critical gas emissions such as CO2, CO and HCl. The results showed that CO2 and CO emissions during firing of clay/SRF mixtures increased due to the thermal decomposition of the organic matter of SRF and that less than 50 wt.% of chlorine was converted to HCl (18-31 ppm). The energy balance showed that the addition of SRF into the ML matrix compensates for a significant part of the natural gas usually used as fuel during firing of these ceramic materials. This was reflected by a thermal energy saving and reduction of CO2 emissions from the decarbonatation of the clay matrix
6
Conley, Jill Anne. "Hygro-thermo-mechanical behavior of fiber optic apparatus." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17308.
7
Sani, Rababe. "Étude des transformations microstructurales de mélanges argile/Combustibles Solides de Récupération (CSR) lors de la cuisson : relations entre propriétés physico-chimiques, mécaniques et thermiques." Electronic Thesis or Diss., Ecole nationale des Mines d'Albi-Carmaux, 2018. http://www.theses.fr/2018EMAC0005.
Abstract:
La valorisation des co-produits riches en matières organiques et inorganiques comme additifs dans des formulations à base d’argile peut améliorer à la fois les performances mécaniques et thermiques des produits de terre cuite, de même que le bilan énergétique des procédés de fabrication de ces matériaux. Cette étude a porté sur l’incorporation de combustibles solides de récupération (CSR) dans un mélange de fabrication des produits de terre cuite pour le génie civil en étroite collaboration avec l’entreprise TERREAL dans le cadre du projet LabCom RESPECTc financé par l’ANR.Premièrement, deux CSR ont été sélectionnés et utilisés comme additifs pour améliorer les produits issus des deux gisements de mélange argileux nommés ML et MC de chez TERREAL. L’influence de la nature, du taux d’incorporation des CSR, de la granulométrie des CSR et de la nature de la matrice argileuse sur les propriétés physico-chimiques, mécaniques et thermiques des mélanges argileux/CSR a été étudiée entre 30°C et 1100°C. Dans tous les cas, l’ajout de CSR a permis d’améliorer le caractère isolant des produits de terre cuite, en diminuant leur conductivité thermique. L’ajout de CSR a aussi permis d’améliorer les propriétés mécaniques des produits, en fonction du type et du taux de CSR ajouté, du taux et de la nature (forme, taille et distribution) de la porosité créée. L’étude a démontré que les interactions entre les minéraux argileux et les éléments inorganiques des CSR avaient un impact important sur les propriétés mécaniques et thermiques. Les résultats ont montré que l’ajout de 4% en masse du CSR15-1 contenant un taux de cendres de 65,7% en masse a conduit à une augmentation de la résistance mécanique du matériau à base de la matrice argileuse ML de l’ordre de 32%. Ensuite, un modèle cinétique du frittage basé sur les variations dimensionnelles des matériaux entre 650°C et 1000°C a été développé à partir de l’analyse thermomécanique (ATM) des mélanges (avec ou sans CSR). L’objectif a été de mieux comprendre les mécanismes du frittage mis en jeu. Le modèle développé a montré une bonne adéquation avec les données expérimentales. Les résultats ont montré que l’étape du frittage thermique de ces mélanges se fait en présence d’une phase liquide et que l’ajout de CSR a permis d’accélérer la densification des matériaux. Cela a conduit à une diminution de la température usuelle de cuisson des produits de terre cuite permettant ainsi un gain énergétique non négligeable. Finalement, une étude environnementale a été réalisée lors de la cuisson des mélanges argileux/CSR. Cette étude a particulièrement été focalisée sur la contribution de CSR au bilan énergétique et à l’impact des émissions des gaz critiques tels que le CO2, le CO et l’HCl. Les résultats ont montré que les émissions de CO2 et de CO lors de la cuisson des mélanges argileux/CSR ont augmenté en raison de la décomposition thermique de la matière organique des CSR et que moins de 50% en masse du chlore a été transformé en HCl (18-31 ppm). Le bilan énergétique effectué a montré que l’ajout de CSR au sein des matrices argileuses ML ou MC compense une part non négligeable du gaz naturel usuellement utilisé comme combustible au cours de la cuisson de ces matériaux. Cela s’est traduit par une économie d’énergie thermique et une réduction des émissions de CO2 provenant de la décarbonatation de la matrice argileuseThe valorization of co-products rich in organic and inorganic materials as additives in formulations based on clay matrix can improve both the mechanical and thermal performances of ceramic materials as well as the energy balance of the manufacturing processes of these products. This study focused on the incorporation of Solid Recovered Fuels (SRF) into the clay ceramics for civil engineering in close collaboration with TERREAL as part of the ANR funded LabCom RESPECTc project. Firstly, two SRF were selected and used as additives to improve the properties of ceramic materials from to clay mixture deposits named ML and MC from TERREAL. The influence of the nature, the amount of SRF, the grain size of SRF and the nature of clay matrix on the physico-chemical, mechanical and thermal properties of the clay/SRF mixtures were studied between 30°C and 1100°C. In all cases, the addition of SRF into the clay mixture (ML or MC) has enhanced the insulating nature of the ceramic materials by reducing their thermal conductivity. The addition of SRF has also improved the mechanical properties of the ceramic materials, depending on the nature and the amount of SRF added, the rate and the nature (shape, size and distribution) of the porosity created. The study demonstrated that interactions between clay minerals and inorganic elements of SRF have a significant effect on mechanical and thermal properties. The results showed that the addition of 4 wt.% of SRF15-1 containing an ash content of 65.7 wt.% into clay matrix ML led to increase the mechanical strength of the material based on the clay matrix ML of the order of 32%. Then, a kinetic model of thermal sintering based on the dimensional variations of ceramic materials between 650°C and 1000°C was developed from thermomechanical analysis (TMA) of the clay mixtures (with or without SRF). The main objective is to better understand the mechanism of the thermal sintering involved. The model developed showed a good adequacy with the experimental data. The results showed that the thermal sintering step of these mixtures is carried out by the presence of a liquid phase and that the addition of SRF has accelerated the densification of ceramic materials. This has led to decrease the usual firing temperature of ceramic materials, allowing a significant energy savings. Finally, an environmental assessment was carried out during the firing of clay/SRF mixtures. This study was particularly focused on the contribution of SRF to the energy balance and impact of critical gas emissions such as CO2, CO and HCl. The results showed that CO2 and CO emissions during firing of clay/SRF mixtures increased due to the thermal decomposition of the organic matter of SRF and that less than 50 wt.% of chlorine was converted to HCl (18-31 ppm). The energy balance showed that the addition of SRF into the ML matrix compensates for a significant part of the natural gas usually used as fuel during firing of these ceramic materials. This was reflected by a thermal energy saving and reduction of CO2 emissions from the decarbonatation of the clay matrix
8
Cunha, Paulo Waldemiro Soares. "Estudo sobre as potencialidades de comp?sitos ? base de gesso e fibras de coco seco para aplica??o na constru??o civil." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12847.
Abstract:
Made available in DSpace on 2014-12-17T14:07:19Z (GMT). No. of bitstreams: 1
PauloWSC_TESE.pdf: 3368472 bytes, checksum: 6f9f6907ea0f81a6a00e41d776e566c5 (MD5)
Previous issue date: 2012-12-28The use of gypsum, one of the oldest building materials for the construction industry in the country has been experiencing a significant and steady growth, due to its low cost and some of its properties that confer comparative advantage over other binder materials. Its use comprises various applications including the coating of walls and the production of internal seals and linings. Moreover, the fibers are being increasingly incorporated into arrays fragile in an attempt to improve the properties of the composite by reducing the number of cracks, the opening of the same and its propagation velocity. Other properties, depending on the function of the component material or construction, among these thermal and acoustic performances, are of great importance in the context of buildings and could be improved, that is, having better performance with this embodiment. Conduct a comparative study of physico-mechanical, thermal and acoustic composite gypsum incorporating dry coconut fiber, in the form of blanket, constituted the main objective of this work. Improving the thermal and acoustic performances of precast gypsum, used for lining and internal vertical fences of buildings, was the purpose of development of these composites. To evaluate the effect of fiber content on the properties of the composites were used to manufacture the composite layer with different thicknesses. The composites were fabricated in the form of plates with dimensions of 500x500x24mm. To facilitate the comparative study of the properties were also made with material gypsum boards only. We then determined the physico-mechanical, thermal and acoustical plaster and composites. The results indicated that the composites were significant gains in relation to thermal performance and also acoustic, in certain frequency range, increasing the thickness of the blanket. Concerning other physical-mechanical properties, the results showed that although the compressive strength was lower than for the composite did not occur after a fracture catastrophic failure. The same trend was observed with regard to resistance to bending, since the composites have not suffered sudden rupture and still continued after the load supporting point of maximum load
A utiliza??o do gesso, um dos mais antigos materiais de constru??o, pela ind?stria da constru??o civil no Pa?s, vem experimentando um sens?vel e constante crescimento, em fun??o do seu baixo custo e de algumas de suas propriedades que lhe conferem vantagem comparativa em rela??o a outros materiais ligantes. Sua utiliza??o compreende diversas aplica??es entre as quais o revestimento de paredes e a confec??o de veda??es internas e de forros. Por outro lado, as fibras v?m sendo, cada vez mais, incorporadas em matrizes fr?geis, na tentativa de melhorar as propriedades do comp?sito, atrav?s da redu??o do n?mero de fissuras, da abertura das mesmas e da sua velocidade de propaga??o. Dependendo da fun??o do material ou do componente da constru??o, os desempenhos t?rmico e ac?stico, assumem grande import?ncia no contexto das edifica??es e tamb?m poderiam ser melhoradoscom a incorpora??o de fibras. Dentre as fibras vegetais, a fibra de coco seco apresenta um grande potencial, superior ?s vantagens comparativas das demais fibras, tal como uma maior resist?nciafrente ? alcalinidade caracter?stica das matrizes ciment?cias. Realizar um estudo comparativo das propriedades f?sico-mec?nicas, t?rmicas e ac?sticas de comp?sitos ? base de gesso com incorpora??o de fibra de coco seco, sob a forma de manta, constituiu-se no objetivo geral deste trabalho. Para tanto os materiais comp?sitos foram confeccionados em forma de placas, pain?is sandu?ches, com dimens?es de 500x500x24mm, sendo as camadas externas constitu?das pelogesso e a central (recheio) pela manta de fibra de coco seco. Para avaliar a influ?ncia do teor de fibras nas propriedades dos comp?sitos foram utilizadas na confec??o dos mesmos mantas com espessuras de 8 e 10 mm. Para possibilitar o estudo comparativo das propriedades foram tamb?m confeccionadas placas apenas com gesso. Foram ent?o determinadas as propriedades f?sico-mec?nicas, t?rmicas e ac?sticas do gesso e dos comp?sitos. Os resultados indicaram que para os comp?sitos ocorreram ganhos significativos em rela??o aos desempenhos t?rmico e tamb?m ac?stico, na faixa de frequ?ncia de 102,28 Hz a 1.150,00 Hz, ganhos esses crescentes com a espessura da manta. Em rela??o ?s demais propriedades f?sico-mec?nicas, os resultados mostraram que embora a resist?ncia ? compress?o tenha sido inferior para os comp?sitos, as fibras apenas evitaram um rompimento brusco, uma vez que as mesmas n?o atuam como refor?o para esse tipo de solicita??o. O mesmo comportamento ocorreu em rela??o ? resist?ncia ? flex?o, uma vez que os comp?sitos n?o sofreram ruptura brusca e ainda continuaram suportando carga depois do ponto de carga m?xima
9
Cisse, Ousseynou. "Caractérisation du comportement hygro-mécanique des fibres liberiennes élémentaires issues du chanvre." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2031/document.
Abstract:
Ce travail de thèse, s'inscrit dans un accord co-tutelle entre l’École Polytechnique de Thiès du Sénégal, et de l'Université de Franche-Comté. Il a été réalisé au Département de Mécanique Appliquée de l'institut FEMO-ST à Besançon (France). [...]L'objectif de cette thèse est de contribuer à la caractérisation du comportement thermo-hygro-mécaniques des fibres libériennes élémentaires issues du chanvre. Les fibres élémentaires testées dans ce travail ont des diamètres extérieurs moyens d'environ 20µm et des longueurs utiles de l'ordre de 10mm. Des essais couplant des chargements mécaniques, hygroscopiques et thermiques sont réalisés afin d'apporter des éléments de compréhension sur le comportement des fibres et de collecter une base de données sur leurs performances mécaniques.Trois types de comportement sont identifiés sur les fibres en traction quasi statique en fluage pour les différents niveaux hygro-thermique testés. Une rigidification de la fibre est révélée sous chargements cycliques progressifs dans des conditions environnementales constantes. Une chute du module d' Young initial de la fibre est remarquée quand l'humidité relative augmente. Une accélération de la vitesse de déformation différée de la fibre est obtenue en fluage lorsque des cycles d'humidité relative sont appliqués. Une baisse des propriétés mécaniques des fibres sous l'effet de la température est également observée. Elle dépend directement du niveau de la durée de l'exposition à la températureThe thesis work joins in the framework in joint supervision between the Polytechnic school in Thies (Sénégal) and the University of Franche-Comté (France)[...]The aim of this thesis is to contribute to the characterization of thermo-hygro-mechanical behaviour of elementary hemp fibres. These fibres used in this work have an average diameter approximately 20µm and useful length of only 10 mm. The méchanical, hygroscopic and thermal coupling testing are realized to provide some understanding of the behaviour of the hemp fibres and to collect details from a database on their mechanical performance.From the uniaxial quasi static tensile tests and creep tests, three categories of behaviours are measured and observed. How ever subject to constant environmental conditions, a fibre hardening is observed under cyclic tensile loading. It was also found that a drop of the initial Young 's modulus of the hemp fibres when the relative humidity gradually increases. Thus, the strain rates measured on the fibres during creep exhibited a speeding up relative humidity cycles are imposed . We found also that the mechanical properties of the fibres decrease under temperature effects. It depends directly on the level and exposure time to temperature
10
Cohen, Ellann. "Thermal properties of advanced aerogel insulation." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67795.
Abstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 74-76).
Buildings consume too much energy. For example, 16.6% of all the energy used in the United States goes towards just the heating and cooling of buildings. Many governments, organizations, and companies are setting very ambitious goals to reduce their energy use over the next few years. Because the time periods for these goals are much less than the average lifetime of a building, existing buildings will need to be retrofitted. There are two different types of retrofitting: shallow and deep. Shallow retrofits involve the quickest and least expensive improvements often including reducing infiltration around windows, under doors, etc and blowing more insulation into the attic. Deep retrofits are those that involve costly renovation and typically include adding insulation to the walls and replacing windows. A new, easily installable, inexpensive, and thin insulation would move insulating the walls from the deep retrofit category to the shallow retrofit category and thus would revolutionize the process of retrofitting homes to make them more energy efficient. This thesis provides an overview of a concept for a new, easily installable, inexpensive, thin aerogel-based insulation and goes into detail on how the thermal properties of the aerogel were measured and validated. The transient hot-wire method for measuring the thermal conductivity of very low thermal conductivity silica aerogel (1 0mW/m K at 1 atm) along with a correction for end effects was validated with the NIST (National Institute of Standards and Technology) Standard Reference Material 1459, fumed silica board to within 1 mW/mK. Despite the translucence of the aerogel at certain wavelengths, radiation is not an issue through the aerogel during the hot-wire test but may be an issue in actual use as an insulation. The monolithic aerogel thermal conductivity drops significantly with slightly reduced pressure (3.2 mW/m K at 0.1atm). For the final composite insulation, the new silica aerogel formula is a great choice and it is recommended to reduce the pressure around the aerogel to 1 / 1 0 th. In the future, a prototype of an insulation panel combining a 3-D truss structure, monolithic or granular silica aerogel, and reduced pressure will be constructed and tested.
by Ellann Cohen.
S.M.
11
Yun, Tae Sup. "Mechanical and Thermal Study of Hydrate Bearing Sediments." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7247.
Abstract:
Gas hydrate is a naturally occurring crystalline compound formed by water molecules and encapsulated gas molecules. The interest in gas hydrate reflects scientific, energy and safety concerns - climate change, future energy resources and seafloor stability. Gas hydrates form in the pore space of sediments, under high pressure and low temperature conditions. This research focuses on the fundamental understanding of hydrate bearing sediments, with emphasis on mechanical behavior, thermal properties and lens formation. Load-induced cementation and decementation effects are explored with lightly cemented loose and dense soil specimens subjected to ko-loading; the small-strain stiffness evolution inferred from shear wave velocity measurement denounces stiffness loss prior to structural collapse upon loading. Systematic triaxial tests address the intermediate and large strain response of hydrate bearing sediments for different mean particle size, applied pressure and hydrate concentration in the pore space; hydrate concentration determines elastic stiffness and undrained strength when Shyd>45%. A unique sequence of particle-level and macro-scale experiments provide new insight into the role of interparticle contact area, coordination number and pore fluid on heat transfer in particulate materials. Micro-mechanisms and necessary boundary conditions are experimentally analyzed to gain an enhanced understanding of hydrate lens formation in sediments; high specific surface soils and tensile stress fields facilitate lens formation. Finally, a new instrumented high-pressure chamber is designed, constructed and field tested. It permits measuring the mechanical and electrical properties of methane hydrate bearing sediments recovered from pressure cores without losing in situ pressure (~20MPa).
12
Hovell, Ian. "Dynamic mechanical thermal properties of moulded poly(vinylchloride) swollen with organic liquids." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/33149.
Abstract:
Compression-moulded unplasticised poly(vinylchloride) (uPVC) was swollen with various organic liquids at two temperatures, 60°C and 30°C, both temperatures being below the glass transition temperature of uPVC. Liquids were chosen to give a range of solubility parameters, molecular sizes and ability to form hydrogen bonds. It was hoped to find a PVC–liquid system which behaved similarly to PVC swollen with vinyl chloride monomer (VCM).
13
Wain, Susan Elizabeth. "Thermal and mechanical properties of pulverised fuel boiler slags." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/8209.
14
Curran, J. A. "Thermal and mechanical properties of plasma electrolytic oxide coatings." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598226.
Abstract:
A critical review of the current knowledge of PEO coating characteristics and properties is made, and several areas requiring more accurate or more detailed investigations are identified. A leading commercial product – the KeroniteTM coating for aluminium alloys – is the used as a basis for the investigation of the microstructure and properties of PEO coatings. Coating structure and morphology are studied quantitatively to investigate their growth mechanism. Composition is accurately determined for the first time, allowing predictions of physical, mechanical and thermal properties to be made. Particular attention is also paid to the presence of amorphous material and fine-scale porosity – properties which had previously been neglected. The latter is critical to the understanding of coating formation and the capacity for coating impregnation, and is measured and characterised using numerous porosimetry techniques. Mechanical properties of the coatings are characterised using indentation and macroscopic techniques such as beam bending. Correlations are established between the observed structure and measured physical properties such as hardness, local modulus and global stiffness. It is found that wear resistance can also be explained on the basis of the measured mechanical properties and structure. The discovery of low coating stiffness means that high-temperature applications, which had previously been dismissed on the basis of thermal expansion mismatch between the coating and substrate, may indeed be possible. The thermal stability of the coatings is therefore investigated and their stability up to 800°C is demonstrated. Residual stresses are measured and explained in terms of the postulated coating growth mechanism.
15
Johnson, Jeremy A. (Jeremy Andrew). "Optical characterization of complex mechanical and thermal transport properties." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68543.
Abstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.Page 176 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 163-175).
Time-resolved impulsive stimulated light scattering (ISS), also known as transient grating spectroscopy, was used to investigate phonon mediated thermal transport in semiconductors and mechanical degrees of freedom linked to structural relaxation in supercooled liquids. In ISS measurements, short optical pulses are crossed to produce a periodic excitation profile in or at the surface of the sample. Light from a probe beam that diffracts off the periodic material response is monitored to observe the dynamics of interest. A number of improvements were put into practice including the ability to separate so-called amplitude and phase grating signal contributions using heterodyne detection. This allowed the measurement of thermal transport in lead telluride and gallium arsenide-aluminum arsenide superlattices, and also provided the first direct observation of the initial crossover from diffusive to ballistic thermal transport in single crystal silicon and gallium arsenide at room temperature. Recent first-principles calculations of the thermal conductivity accumulation as a function of phonon mean free path allowed direct comparison to our measured results. In an effort to test theoretical predictions of the prevailing first principles theory of the glass transition, the mode coupling theory (MCT), photoacoustic measurements throughout much of the MHz acoustic frequency range were conducted in supercooled liquids. Longitudinal and shear acoustic waves were generated and monitored in supercooled liquid triphenyl phosphite in order to compare the dynamics. An additional interferometric technique analogous to ISS was developed to probe longitudinal acoustic waves at lower frequencies than was typically accessible with ISS. Lower frequency acoustic data were collected in supercooled tetramethyl tetraphenyl trisiloxane in conjunction with piezotransducer, ISS, and picosecond ultrasonics measurements to produce the first truly broadband mechanical spectra of a viscoelastic material covering frequencies continuously from mHz to hundreds of GHz. This allowed direct testing of the MCT predicted connection between fast and slow relaxation in supercooled liquids. Measurements of the quasi-longitudinal speed of sound in the energetic material cyclotrimethylene trinitramine (RDX) were also performed with ISS and picosecond ultrasonics from 0.5 to 15 GHz in order to resolve discrepancies in published low and high frequency elastic constants.
by Jeremy A. Johnson.
Ph.D.
16
Cerezo, Frances Therese, and francestherese_cerezo@hotmail com. "Thermal stability and mechanical property of polymer layered graphite oxide composites." RMIT University. Applied Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080627.161157.
Abstract:
Polymer composites formed from layered fillers with high surface volume ratio show enhanced reinforcement. Graphite oxide is a high modulus material that can be separated into thin layers with high surface area. The aim of this study is to prepare polymer layered graphite oxide composites using functionalised polyolefin to enhance compatibility with various forms of layered graphite oxide in varying concentration. Functionalised polyolefins reinforced with layered graphite oxides and expanded graphite oxides were prepared using solution blending and melt blending methods. Three different mixing methods with varying shear intensity were employed to prepare polymer layered graphite oxide composites. The crystalline structure, thermal and mechanical properties of the prepared polymer layered graphite oxide composites was studied. Oxidised graphite prepared from the Staudenmaier method and its exfoliated form were dispersed in poly(ethylene-co-methyl acrylate-co-acrylic acid) (EMAA) via solution blending to prepare EMAA layered composites. The thermal stability was determined using thermogravimetric analysis. The EMAA layered composites showed higher thermal stability in comparison with pure EMAA. The mechanical properties of these EMAA layered composites were determined through dynamic mechanical analysis. Shear modulus, yield stress and storage modulus of EMAA in the presence of graphite oxide fillers decreased. A solution blending method was used to prepare poly(propylene-grafted-maleic anhydride) layered expanded graphite oxide composites (PPMA-EGO). Two types of PPMA-EGO were prepared using different mixing methods - low and high shear were employed. The effects of preparative mixing methods on the PPMA-EGO properties were investigated. The mechanical properties of PPMA-EGO obtained from dynamic mechanical analysis indicated that EGO had a reinforcing effect on the elastic behaviour of PPMA-EGO. This is due to strong interfacial adhesion between PPMA and EGO as a result of hydrogen bonding. The elastic behaviour of PPMA-EGO was affected by the surface area of graphite flakes. Low sheared PPMA-EGO elastic behaviour was found to be higher compared with that of high sheared PPMA-EGO. A melt blending method was used to prepare PPMA-EGO with varying EGO concentration. The interconnected network structure of EGO in the PPMA-EGO was not observed as shown by its scanning electron microscopy images. Thermogravimetric analysis of PPMA-EGO indicates increased decomposition temperature of the PPMA matrix. Dynamic mechanical analysis showed enhanced storage modulus of PPMA-EGO. The maximum elastic modulus of PPMA-EGO was observed at 3 %wt of EGO. The electrical conductivity of PPMA-EGO was measured only for EGO concentrations above 2 %wt. The EGO concentration was found to be the most critical factor in the enhancement of the electrical conductivity of PPMA-EGO. Wide angle X-ray diffraction analysis of all polymer layered graphite oxide composites revealed no change in interlayer spacing of graphite layers, indicating the absence of EMAA intercalation in the graphite layers. The crystallisation temperature and crystallinity of all polymer layered graphite oxide composites were determined using differential scanning calorimetry. The results indicated that graphite oxide and expanded graphite oxides acted as nucleating agents in inducing the crystallisation of functionalised polyolefin in the layered composites. However, the degree of crystallinity of functionalised polyolefin decreased in the layered composites.
17
Gril, Joseph. "Une modelisation du comportement hygro-rheologique du bois a partir de sa microstructure." Paris 6, 1988. http://www.theses.fr/1988PA066271.
Abstract:
L'etude concerne la prise en compte des variations d'humidite dans la representation du comportement mecanique du bois dans la direction des fibres. On rapelle des notions de base sur le bois, puis on analyse des resultats experimentaux sur le couplage hygromecanique. On propose ensuite des modeles uniaxiaux de la mecanosorption, basee sur l'ultrastructure de la matiere lignocellulosique. L'action de l'eau est modelisee de deux manieres. On prend enfin explicitement en compte la structure tridimensionnelle et l'orientation du reseau microfibrillaire. On propose une interpretation des contraintes internes generees a l'echelle moleculaire par la lignification et le sechage
18
Skow, Erik (Erik Dean). "Processing and thermal properties of molecularly oriented polymers." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40368.
Abstract:
Thesis (S.M. in Mechanical Engineering and Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 61-63).
High molecular weight polymers that are linear in molecular construction can be oriented such that some of their physical properties in the oriented direction are enhanced. For over 50 years polymer orientation and processing has been extensively studied to improve the mechanical properties of polymers. In more recent history the anisotropic thermal properties of oriented polymers have been studied. This thesis investigates the thermal properties of Ultra High Molecular Weight Polyethylene (UHMW-PE) and explores applications for the same. This thesis details an effective means of aligning the molecules in bulk polyethylene sheets through stretching in the gel state. Tests have shown that bulk UHMW-PE can be stretched 50-80 times in xylene. The thermal conductivity of bulk UHMW-PE is 0.3 W/mK, while that of a sample stretched 20-25 times is over 4.5 W/mK.
by Erik Skow.
S.M.in Mechanical Engineering and Naval Architecture and Marine Engineering
19
El-Khoja, Amal M. N. "Mechanical, thermal and acoustic properties of rubberised concrete incorporating nano silica." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18351.
Abstract:
Very limited research studies have been conducted to examine the behaviour
of rubberised concrete (RuC) with nano silica (NS) and addressed the acoustic
benefits of rubberised concrete. The current research investigates the effect of
incorporating colloidal nano silica on the mechanical, thermal and acoustic
properties of Rubberised concrete and compares them with normal concrete
(NC).
Two sizes of rubber were used RA (0.5 – 1.5 mm) and RB (1.5 – 3 mm). Fine
aggregate was replaced with rubber at a ratio of 0%, 10%, 20% and 30% by
volume, and NS is used as partial cement replacement by 0%, 1.5% and 3%.
A constant water to cement ratio of 0.45 was used in all concrete mixes.
Various properties of rubberised concrete, including the density, water
absorption, the compressive strength, the flexural strength, splitting tensile
strength and the drying shrinkage of samples was studied as well as thermal and acoustic properties.
Experimental results of compressive strength obtained from this study together
with collected comprehensive database from different sources available in the
literature were compared to five existing models, namely Khatib and Bayomy- 99 model, Guneyisi-04 model, Khaloo-08 model, Youssf-16 model, and
Bompa-17 model. To assess the quality of predictive models, influence of
rubber content on the compressive strength is studied. An artificial neural
network (ANN) models were developed to predict compressive strength of
RuC using the same data used in the existing models. Three ANN sets namely
ANN1, ANN2 and ANN3 with different numbers of hidden layer neurons were
constructed. Comparison between the results given by the ANN2 model and
the results obtained by the five existing predicted models were presented. A
finite element approach is proposed for calculating the transmission loss of
concrete, the displacement in the solid phase and the pressure in the fluid
phase is investigated. The transmission loss of the 50mm concrete samples is
calculated via the COMSOL environment, the results from the simulation show
good agreement with the measured data.
The results showed that, using up to 20% of rubber as fine aggregate with the
addition of 3% NS can produce a higher compressive strength than the NC.
Experimental results of this research indicate that incorporating nano silica into
RuC mixes enhance sound absorption and thermal conductivity compared to
normal concrete (NC) and rubberised concrete without nano silica. This work
suggests that it is possible to design and manufacture concrete which can
provide an improvement to conventional concrete in terms of the attained
vibro-acoustic and thermal performance.Libyan Ministry of Higher Education
20
Kamani, Sandeep Kumar. "Influence of defects on thermal and mechanical properties of metals." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2901.
21
Aksel, Cemail. "Thermal shock behaviour and mechanical properties of magnesia-spinel composites." Thesis, University of Leeds, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275609.
22
Barlow, Lyndsey J. "Thermal, mechanical and electrical properties of liquid crystalline polymer electrolytes." Thesis, University of Aberdeen, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401497.
Abstract:
It is generally accepted that ion transport in polymer electrolytes is strongly coupled to the local viscosity of the host polymer and that, in most cases, appreciable ionic conductivity below the glass transition temperature is not observed. Recent literature suggests that this may not always be the case and examples of polymer electrolytes exhibiting ionic conductivity decoupled from the polymeric motions have been reported. This thesis investigates one such system, a liquid crystalline polymer electrolyte, which has been reported to show measurable conductivity in the sold phase. The aim is to investigate such decoupled behaviour, how it may be optimised and to understand the conductivity mechanism. The thermal, mechanical and electrical properties of lithium perchlorate and lithium triflate complexes of a liquid crystalline polymer and its non-liquid crystalline analogue have been investigated. These studies suggest that the conductivity is not in fact decoupled from the local motions of the polymer. Selected complexes are then examined further and conductivities measured under variable pressure. From these data, activation energies, volumes and decoupling constants are calculated. These results show that, although not fully coupled, these complexes cannot be considered to exhibit decoupled conductivity and, in fact, the non-liquid crystalline electrolytes actually show a greater tendency towards decoupled behaviour than their liquid crystalline counterparts. In the final chapter, the two polymers are complexed with lithium trifluoromethanesulphonyl imide, a salt that has been reported to give enhanced conducivities. It is found that using this salt does indeed raise conductivities, but also reduces tendencies towards decoupled behaviour.
23
Okeke, George Obiora Ugochukwu. "Physico-thermal properties of TiO2 nanoparticles using molecular dynamics simulations with relevance to thermal conductance of nanofluids." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/6302/.
Abstract:
Nanoparticles have attracted the attention of researchers in a number of multidisciplinary fields as they possess enhanced structural and physical properties, which make them desirable to a wide range of industries. These enhancements have mostly been attributed to nanoparticles possessing large surface area-to-volume ratio. The concept of engineered nanofluids refers to making stable suspension of nanoparticles in base fluids to provide more efficient and thermally enhanced effective thermal conductance in a number of engineering applications involving heat transfer processes. Although experimental and computational studies have shown significant enhancement of thermal conductivity of nanofluids compared to the conventional heat transfer fluids, the underlying mechanism behind this enhancement is still not well understood. Out of the several mechanisms which have been proposed in the literature to be behind this enhancement of thermal conductivity, nanoparticle clustering seems to evolve as a relatively more significant factor for the enhancement of effective conductance of nanofluids and hence requires more detailed investigation in the future. In this study, initially, numerical investigations are conducted to study the effect of particle clustering on thermal conductivity of nanofluids. The degree of thermal enhancement is analysed for different factors that capture particle clustering, such as aggregate size, particle concentration, interfacial thermal resistance, and fractal and chemical dimensions. This analysis is conducted for three model water-based nanofluids of aluminium oxide (Al2O3), copper oxide (CuO) and titanium dioxide (TiO2) nanoparticles in which particle concentrations are varied up to 4 volume %. Results from the numerical work are validated using available experimental data. Studies showed that predicted and experimental data for thermal conductivity enhancement are in good agreement as particle clustering is seen to influence effective thermal conductance of the model nanofluids. Considering this observation and to further understand the mechanism behind particle clustering, particle scale properties such as thermodynamic, structural, surface and interaction force properties are investigated in vacuum and liquid environments at different temperatures, using Molecular Dynamics (MD) simulations. These simulations are carried out on TiO2 nanoparticles (with particle sizes ranging between 2 – 6nm) as a model system owing to their wide industrial applications, with a particular focus on two mostly encountered forms of TiO2 namely; anatase and rutile. From MD simulations, the Radial Distribution Function (RDF) plots of the particles in vacuum revealed much higher crystallinity with peaks of almost an order higher than that of the nanoparticles in water. For anatase, surface energy of the particles in vacuum is seen to be higher than that of the particles in water by about 100% for the smaller size particles (especially for 2 and 3nm), and about 60% for relatively larger particles (especially for 4 to 6 nm). In both environments, surface energy of anatase nanoparticles is also seen to increase with particle size to a maximum value of critical particle size (i.e. 4 nm) after which no further significant increase in surface energy is observed. Finally, force – displacement analysis which captures interaction force relations is conducted for different particle sizes in vacuum and water environments, using MD simulations. This analysis provides interaction force information which is vital in studying particle interactions. In this study, the nanoparticles are seen to be more attractive at a smaller size and the attraction increases as the particle size increases. Particles are also seen to become repulsive at initial contact. Overall, this thesis presents vital information on particle scale properties of TiO2 nanoparticles (as a model system) under different environments. These properties are known to influence clustering of nanoparticles which in turn influence thermal enhancement of nanofluids. In the near future, knowledge of these particle scale properties will aid in the development of more enhanced nano and bulk systems with better physico-thermal properties, to meet the ever growing requirement for technological advancement.
24
Rummel, Nicholas J. "Dynamic mechanical analysis of magnetic tapes at ultra-low frequencies." Scholarly Commons, 2011. https://scholarlycommons.pacific.edu/uop_etds/773.
Abstract:
The purpose of this thesis is to investigate the correlated effects of temperature and frequency on the viscoelastic behavior of magnetic tapes, using a custom, ultra-low frequency, dynamic mechanical analyzer. The long-term mechanical and thermal properties of magnetic tapes can be simulated using high temperature and low frequency dynamic mechanical analysis (DMA) experiments. These experiments investigate how the viscoelastic characteristics of tape samples influence the extent to which the tape deforms. The experiments and analyses implemented in this paper examine the influence of the molecular structure on the viscoelasticity of magnetic tapes. Experiments were performed on a variety of magnetic tapes, including poly( ethylene terephthalatc) (PET), poly( ethylene naphthalate) (PEN), metallized poly( ethylene terephthalate) (MPET), and metallized Spaltan (M-SPA). To determine characteristic relating to the magnetic tape substrates, additional experiments examined PEN and PET substrates by removing the front and back magnetic layers from the tape sample. Due to the viscoelastic behavior of the tapes, a time delay was present between the strain and stress signals, which was determined using a Fourier transform program. The elastic modulus (E), storage modulus (E'), loss modulus (E"), and loss tangent (tan 8) were obtained from the time delay for each of the DMA experiments
25
Xie, Weidong. "Thermo-mechanical evaluation of interfacial integrity in multilayered microelectronic packages." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17380.
26
Zhao, Yang. "Evaluation and characterisation of thermal barrier coatings." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/evaluation-and-characterisation-of-thermal-barrier-coatings(b6b8d5ef-0cd3-4257-9563-6a6b1626cb49).html.
Abstract:
Evaluation and characterisation of thermal barrier coatings (TBCs) have been conducted correlating microstructure with physical and mechanical properties, to further understand TBC failure mechanisms and performances in this thesis. A modified four-point bending test was employed to investigate the interfacial toughness of atmospheric plasma sprayed TBCs. The delamination of the TBCs occurred mainly within the topcoat. The energy release rate increased from ~50 J/m-2 for as-sprayed conditions to ~120 J/m-2 after annealing at 1150 ºC for 200 hours with a loading phase angle about 42º. Micro X-ray tomography revealed how various types of imperfections developed near the interface and the 3D interface was characterised. Stress measurements by photoluminescence piezospectroscopy (PLPS) and analytical solutions were combined to investigate the local stress around spherically symmetrical portions of a TGO layer formed on Fecralloy. Spherical indenters were used to create curvature with different curvature radii and depths on alloys. The effect of curvature radius on stress was found to be more significant than the depth of local curved area. TGO stress as a function of oxidation time at the curved areas was also discussed. Electron beam physical vapour deposited (EBPVD) TBCs with a β-(Ni,Pt)Al bond coat on CMSX4 substrate were investigated by micro X-ray computed tomography (XCT). The 3D microstructures evolution and damage accumulation were studied. 3D interfacial roughness was calculated and compared to scanning electron microscope image analysis. The calculated interfacial roughness did not change much even after 200 thermal cycles, indicating there was not obvious rumpling in this TBCs sample. Commercial simple and Pt-modified aluminide coatings were studied and compared. Both coatings consisted mainly of β-NiAl phase. Thermogravimetric analysis (TGA) tests indicated that the Pt-modified aluminide coating was much more resistive for oxidation than simple aluminide coating. Instrumented indentation was used to measure the mechanical properties, showing the coatings had similar young’s modulus around 130 GPa while Pt-modified aluminide coating was more ductile and had a higher fracture toughness than simple aluminide coating. The Raman spectra of yttria-stabilised zirconia (YSZ) in the temperature range of 25-1100 ºC were investigated. The peak shift and broadening were carefully analysed. The thermal mismatch stress was found to have a negligible effect on the Raman shift. The dependence can be used to monitor the temperature in YSZ without contact.
27
Othuman, Mydin Md Azree. "Lightweight foamed concrete (LFC) thermal and mechanical properties at elevated temperatures and its application to composite walling system." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/lightweight-foamed-concrete-lfc-thermal-and-mechanical-properties-at-elevated-temperatures-and-its-application-to-composite-walling-system(5a13ec7f-d460-4354-a296-6d1ffecff971).html.
Abstract:
LFC is cementatious material integrated with mechanically entrained foam in the mortar slurry which can produce a variety of densities ranging from 400 to 1600 kg/m3. The application of LFC has been primarily as a filler material in civil engineering works. This research explores the potential of using LFC in building construction, as non-load-bearing partitions of lightweight load-bearing structural members. Experimental and analytical studies will be undertaken to develop quantification models to obtain thermal and mechanical properties of LFC at ambient and elevated temperatures. In order to develop thermal property model, LFC is treated as a porous material and the effects of radiant heat transfer within the pores are included. The thermal conductivity model results are in very good agreement with the experimental results obtained from the guarded hot plate tests and with inverse analysis of LFC slabs heated from one side. Extensive compression and bending tests at elevated temperatures were performed for LFC densities of 650 and 1000 kg/m3 to obtain the mechanical properties of unstressed LFC. The test results indicate that the porosity of LFC is mainly a function of density and changes little at different temperatures. The reduction in strength and stiffness of LFC at high temperatures can be predicted using the mechanical property models for normal weight concrete provided that the LFC is based on ordinary Portland cement. Although LFC mechanical properties are low in comparison to normal weight concrete, LFC may be used as partition or light load-bearing walls in a low rise residential construction. To confirm this, structural tests were performed on a composite walling system consisting of two outer skins of profiled thin-walled steel sheeting with LFC core under axial compression, for steel sheeting thicknesses of 0.4mm and 0.8mm correspondingly. Using these test results, analytical models are developed to calculate the maximum load-bearing capacity of the composite walling, taking into consideration the local buckling effect of the steel sheeting and profiled shape of the LFC core. The results of a preliminary feasibility study indicate that LFC can achieve very good thermal insulation performance for fire resistance. A single layer of 650 kg/m3 density LFC panel of about 21 mm would be able to attain 30 minutes of standard fire resistance rating, which is comparable to gypsum plasterboard. The results of a feasibility study on structural performance of a composite walling system indicates that the proposed panel system, using 100mm LFC core and 0.4mm steel sheeting, has sufficient load carrying capacity to be used in low-rise residential construction up to four-storeys.
28
Dames, Christopher Eric. "Thermal properties of nanowires and nanotubes : modeling and experiments." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38259.
Abstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references.
Nanowires and nanotubes have drawn a great deal of recent attention for such potential applications as lasers, transistors, biosensors, and thermoelectric energy converters. Although the thermal properties of nanowires can differ greatly from their bulk counterparts, the theoretical and experimental understanding of these differences is still limited. Thermal performance is especially important for nanowire thermoelectrics, which are expected to have energy conversion efficiencies far superior to bulk materials. This efficiency increase may lead to a broad range of applications for reliable, solid-state energy conversion, including household refrigeration and waste heat scavenging for power generation. In this thesis, the fundamental thermal properties of nanowires and nanotubes are explored from both theoretical and experimental perspectives. Modeling and experiments on titanium dioxide nanotubes confirm that quantum size effects can cause enhancements in the specific heat at low temperature, while modeling of classical size effects in nanowires and superlattice nanowires shows that the thermal conductivity can be reduced by several orders of magnitude compared to bulk, in agreement with available experimental data.
(cont.) To facilitate further experimental studies of individual nanowires, the "3-omega" methods for thermal properties measurements were made more rigorous, simpler to implement, and generalized to 1-omega and 2-omega methods which may be advantageous for nanoscale systems. These methods are used to deduce the thermal properties of a system from its electrical response at the first, second, or third harmonic of a driving current. Finally, a detailed design and preliminary measurements are presented for a new type of hot-wire probe based on Wollaston wire and used to measure the thermoelectric properties of individual nanowires and nanotubes inside a transmission electron microscope.
by Christopher Eric Dames.
Ph.D.
29
Anghelescu, Mihnea S. "Thermal and Mechanical Analysis of Carbon Foam." View abstract, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3353337.
30
Pakiela, Z., L. Jarosz, K. Nowak, and L. Olejnik. "Thermal Stability and Mechanical Properties of 5483 Al Alloy Processed by ECAP." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35435.
Abstract:
Equal Channel Angular Pressing (ECAP) is one of the methods which allows to obtain ultrafine-grained and nanocrystalline metallic materials. It is well known that microstructure of materials pro-cessed by ECAP in not very stable. There were published many experimental and theoretical evidences of this fact obtained by various methods such as microstructure observations, properties measurement and computer modeling.
The aim of presented paper was to investigate the thermal stability of microstructure and mechanical properties of the Al 5483 alloy processed by ECAP. As a result of performed investigations it was concluded that accumulated plastic deformation has no influence on the thermal stability of Al 5483 alloy processed by ECAP. It was also found that properly chosen parameters of ECAP and subsequent annealing allows to produce materials with high strength and plasticity.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35435
31
Duerr, Joachim Karl Wilhelm. "Finite element analysis of thermal stresses in semiconductor devices." PDXScholar, 1990. https://pdxscholar.library.pdx.edu/open_access_etds/4215.
Abstract:
The failure of integrated circuit due to Silicon fracture is one of the problems associated with the production of a semiconductor device. The thermal stresses, which result in die cracking, are for the most part induced during the cooling process after attaching the die with Gold-Silicon solder. Major factors for stress generation in material systems are commonly large temperature gradients and substantial difference in coefficients of thermal expansion.
32
Deshpande, Girish Nilkanth. "Effect of polysiloxane side groups on chemistry and kinetics of degradation and evolution of pores in the resultant polymer." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/11845.
33
Gauthier, Sylvie 1955. "Synthesis and physical properties of styrene-vinylpyridinium ionomers of various architectures." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72029.
Abstract:
Styrene-4-vinylpyridinium ionomers of different architectures, random and ABA blocks, were synthesized and their thermal and dynamic mechanical properties investigated.The Tg's of the random ionomers were found to increase regularly with increasing ion content, at a rate of about 3.5(DEGREES)C per mole % of ions. In contrast with other ionomeric systems studied before, however, these materials showed only one peak in their tan delta curves, associated with the Tg of the matrix. The absence of a second, high temperature peak suggests the absence of clusters in these vinylpyridinium ionomers, at least at temperatures above their Tg. The storage modulus curves were in agreement with this conclusion.
An elaborate polymerization line was constructed for the production of the block copolymers by living anionic polymerization; a basic design was modified considerably and two new units were completely designed in this laboratory. Only one Tg, associated with the Tg of the polystyrene phase, was observed in DSC measurements for the resulting ionomers. The glass transition of the ionic domains was detected in dynamic mechanical measurements as a shoulder on the low temperature side of the polystyrene transition. This unexpected low value for the Tg of the ionic domains was attributed to plasticization by water.
34
Weisenberger, Matthew Collins. "APPLICATIONS OF MULTIWALL CARBON NANOTUBE COMPOSITES: MECHANICAL, ELECTRICAL AND THERMAL PROPERTIES." Lexington, Ky. : [University of Kentucky Libraries], 2007. http://hdl.handle.net/10225/738.
Abstract:
Thesis (Ph. D.)--University of Kentucky, 2007.Title from document title page (viewed on March 24, 2008). Document formatted into pages; contains: ix, 97 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 91-95).
35
Ghazinezami, Ali. "Fire retardancy, thermal stability and mechanical properties of polymeric based nanocomposites." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/10631.
Abstract:
Polymeric materials have a wide variety of applications in many manufacturing industries. However, because of the molecular structures and chemical compositions of polymeric materials, they have considerably low resistances against fire or heat. Although these materials are highly flammable, their flame retardancy can be improved significantly by incorporating the flame retardant nanomaterials. Nanoclay, nanotalc and graphene are some of the examples of the flame retardant nanomaterials. These are highly cost effective and environmentally friendly for these applications. These inclusions have a great potential to improve thermal, electrical, and mechanical properties of the new materials. This study is mainly focused on the effects of nanoparticle additions in the polyvinyl chloride (PVC) in terms of the flame retardancy. Five sets of nanocomposite materials were prepared using the solvent casting method at different weight percentages of the nanomaterials. The flame retardancy values of the resultant nanocomposite samples were determined using the ASTM UL 94 standard tests. The results of the experiment were also supported by the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Surface characterization of the resultant materials was carried out using scanning electron microscopy (SEM), while mechanical properties were determined through a tensile test method. Test results showed that the flame retardancy values of the new nanostructured materials were significantly enhanced in the presence of nanoscale inclusions, which may be useful for various industrial applications. This study may open up new possibilities of using many nanoscale inclusions in various polymers as flame retardant materials for different industrial applications.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
36
O'Reilly, Michael Patrick. "Mechanical properties of granular materials for use in thermal energy stores." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353925.
37
Deszczynski, Marcin. "Effects of sugars on the mechanical and thermal properties of biopolymers." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289482.
38
Thompson, Ian. "Mechanical properties in liquid environments and thermal shock resistance of aluminas." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47686.
39
Plunkett, Richard. "Assessment of residual composite properties as influenced by thermal mechanical aging." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11072008-063142/.
40
Pan, Deng. "Mechanical properties of diffusion aluminide bond coats for thermal barrier coatings." Available to US Hopkins community, 2003. http://wwwlib.umi.com/dissertations/dlnow/3080741.
41
Shin, Hyun Doug. "Expanding ultrafast photoacoustics for investigation of mechanical properties and thermal transport." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122716.
Abstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 123-135).
To address the need for broadband mechanical spectroscopy, femtosecond laser pulses were used to generate and detect acoustic waves. To expand the acoustic phonon frequency bandwidth and range, a thin metal film, a strongly magnetostrictive galfenol film, and strained piezoelectric InGaN/GaN multiple quantum wells were used as transducers. Acoustic wave detection methods included monitoring of optical transmittance/ reflectance, polarization, and diffraction over time. A magnetostrictive material galfenol (Fe₁₋[subscript x] Ga[subscript x]) with 80 percent iron and 20 percent gallium was used as an acoustic transducer using demagnetostriction effect. Galfenol showed great potential as an optimal transducer for the ultrafast magnetostriction in both longitudinal and shear modes. Strained piezoelectric InGaN/GaN semiconductor superlattices were used to generate and to study longitudinal THz acoustic phonons in GaN based structures. During the investigation of the lifetime of up to a 1.4 THz frequency acoustic phonons, specular reflection from an air/GaN free surface was observed. The photo-excitation of THz acoustic phonons in layered structures was introduced as an effective noninvasive tool to investigate the integrity of the fabrication process. This study opened many possibilities for studying mechanical properties and thermal phonons. Next, thermal conductivity reduction due to carrier-phonon interactions was presented. Phonon contributions are critical in heat transport in semiconductors and insulators. To isolate the carrier contributions to the scattering events, photo-excited carriers were generated in silicon through pulsed laser excitation. To measure thermal conductivity changes, time-domain thermoreflectance and transient thermal grating techniques were employed with a, carefully timed additional excitation pulse for carrier generation.
by Hyun Doug Shin.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemistry
42
Karimzadeh, F., V. Rastar, and M. H. Enayati. "Thermal Stability and Mechanical Properties of Al-Al2O3 Nanocomposite Produced by Mechanical Milling and Hot-Pressing." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34932.
Abstract:
In this study, Al-Al2O3 nanocomposite powders containing 5, 10 and 15 Wt% of nanopowder were
produced by mechanical alloying. For comparing, Al-Al2O3 composite powder containing 5Wt% of
micrometric Al2O3 was also produced. The powder was then hot-pressed in a mold to produce bulked parts.
The effect of Al2O3 content on grain growth, density, hardness and bending strength of bulked composite
was discussed and microstructures were investigated by optical, scanning and transmission electron
microscopy. The results revealed that when nanometric particles were used instead of micrometric
particles the grain growth was reduced, while the increase of particle weight percentage did not affect the
grain growth. The results also showed that when weight percentage of nanometric particles was increased,
although hardness of bulked parts was increased but relative density and bending strength was reduced
severely.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34932
43
Kulamarva, Arun. "Rheological and thermal properties of sorghum dough." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98740.
Abstract:
Sorghum is a gluten free cereal and forms the staple diet of a majority of the populations living in the semi-arid tropics dough. It is usually consumed in the form of bread made from the grain flour. Dough made with sorghum flour has poor viscoelastic properties compared to wheat dough and mechanical methods for production of sorghum roti are scarce. This study was conducted to elucidate the rheological and thermal properties of sorghum dough to establish its behavior. The temperature and amount of water used for preparation of the dough and the composition of the flour were varied. Wheat, soya and black gram flours were used to prepare the composite doughs. Sensory characteristics of roti made with these dough samples by the traditional method and mechanical compression were studied. The results are presented and their implications are discussed.
44
Bailey, Jacob (Jacob S. ). "Experimental determination of the thermal properties of multi-layered surfaces." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83683.
Abstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (page 23).
This paper outlines a project which aims to use Certified Reduced Basis and General Empirical Interpolation Methods to conduct rapid, inexpensive, computationally simple thermal property estimation for the purpose of material identification. In this specific case, thermal conductivity and diffusivity were the parameters of interest. Towards this end, an experimental apparatus was constructed which applied a thermal load to various materials and observed their thermal responses. Bugs in the experimental apparatus were compensated for by way of a MATLAB script, until the data produced by individual tests became highly repeatable. Software was developed which simulated these thermal responses for given thermal loads and "true" parameter values. The materials were put through multiple tests (Laser Flash Test, Transient Plane Source) to independently identify possible values for these thermal properties. The "true" values were then chosen from these possible values based on how well they allowed the simulated response to fit the measured response. It was found that implementation of the CRB and GEIM allowed for an accurate estimate of these "true values," and did so without exhaustively carrying out a finite element analysis for every possible combination of parameters, creating an exponential increase in performance.
by Jacob Bailey.
S.B.
45
Guan, Juan. "Investigations on natural silks using dynamic mechanical thermal analysis (DMTA)." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:c16d816c-84e3-4186-8d6d-45071b9a7067.
Abstract:
This thesis examines the dynamic mechanical properties of natural silk fibres, mainly from silkworm species Bombyx mori (B. mori) and spider species Nephila edulis, using dynamic mechanical thermal analysis, DMTA. The aim is not only to provide novel data on mechanical properties of silk, but also to relate these properties to the structure and morphology of silk. A systematic approach is adopted to evaluate the effect of the three principal factors of stress, temperature and hydration on the properties and structure of silk. The methods developed in this work are then used to examine commercially important aspects of the ‘quality’ of silk. I show that the dynamic storage modulus of silks increases with loading stress in the deformation through yield to failure, whereas the conventional engineering tensile modulus decreases significantly post-yield. Analyses of the effects of temperature and thermal history show a number of important effects: (1) the loss peak at -60 °C is found to be associated the protein-water glass transition; (2) the increase in the dynamic storage modulus of native silks between temperature +25 and 100 °C is due simply to water loss; (3) a number of discrete loss peaks from +150 to +220°C are observed and attributed to the glass transition of different states of disordered structure with different intermolecular hydrogen bonding. Excess environmental humidity results in a lower effective glass transition temperature (Tg) for disordered silk fractions. Also, humidity-dynamic mechanical analysis on Nephila edulis spider dragline silks has shown that the glass transition induces a partial supercontraction, called Tg contraction. This new finding leads to the conclusion of two independent mechanisms for supercontraction in spider dragline silks. Study of three commercial B. mori cocoon silk grades and a variety of processed silks or artificial silks shows that lower grade and poorly processed silks display lower Tg values, and often have a greater loss tangent at Tg due to increased disorder. This suggests that processing contributes significantly to the differences in the structural order among natural or unnatural silks. More importantly, dynamic mechanical thermal analysis is proposed to be a potential tool for quality evaluation and control in silk production and processing. In summary, I demonstrate that DMTA is a valuable analytical tool for understanding the structure and properties of silk, and use a systematic approach to understand quantitatively the important mechanical properties of silk in terms of a generic structural framework in silk proteins.
46
Xu, Shuangyan. "Evaluating Thermal and Mechanical Properties of Electrically Conductive Adhesives for Electronic Applications." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27112.
Abstract:
The objective of this study was to evaluate and gain a better understanding of the short-term impact performance and the long-term durability of electrically conductive adhesives for electronic interconnection applications. Three model conductive adhesives, designated as ECA1, ECA2 and ECA3, supplied by Emerson & Cuming, were investigated, in conjunction with printed circuit board (PCB) substrates with metallizations of Au/Ni/Cu and Cu, manufactured by Triad Circuit Inc.
Effects of environmental aging on the durability of conductive adhesives and their joints were evaluated. All the samples for both mechanical tests and thermal tests were aged at 85%, 100%RH for periods of up to 50 days. Studies of bulk conductive adhesives suggested that both plasticization, which is reversible and further crosslinking and thermal degradation, which are irreversible, might have occurred upon exposure of ECAs to the hot/wet environment. The durability of electrically conductive adhesive joints was then investigated utilizing the double cantilever beam (DCB) test. It was observed that the conductive adhesive joint was significantly weakened following hydrothermal aging, and there was a transition from cohesive failure to interfacial failure as aging continued. A comparative study of the durability of different conductive adhesive and substrate metallization combinations suggested that the resistance of the adhesive joints to moisture attack is related to the adhesive properties, as well as the substrate metallizations. It was noted that the gold/adhesive interface had better resistance to moisture attack than the copper/adhesive interface. A reasonable explanation of this phenomenon was given based upon the concept of surface free energy and interfacial free energy. XPS analysis was performed on the fractured surfaces of DCB samples. For adhesive joints with copper metallization, copper oxide was detected on the failed surfaces upon exposure of the conductive adhesive joints following aging. XPS analysis on the fractured surfaces of adhesive joints with Au metallization suggested that diffusion of Cu to the Au surface might have happened on the Au/Ni/Cu plated PCB substrates during aging.
The impact performance of conductive adhesives was quantitatively determined using a falling wedge test. This unique impact resistance testing method could serve as a useful tool to screen conductive adhesives at the materials level for bonding purpose. Moreover, this test could also provide some useful information for conductive adhesive development. This study revealed that the viscoelastic energy, which is a result of the internal friction created by chain motions within the adhesive material, played an important role in the impact fracture behavior of the conductive adhesives. This study also demonstrated that the loss factor, evaluated at the impact environment conditions, is a good indicator of a conductive adhesive's ability to withstand impact loading.Ph. D.
47
DeVincent, Sandra Marie. "Interfacial effects on the thermal and mechanical properties of graphite/copper composites." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1061300766.
48
LeBaut, Yann P. "Thermal aspect of stereolithography molds." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/15991.
49
Pitié, Frédéric. "High temperature thermal energy storage : encapsulated phase change material particles : determination of thermal and mechanical properties." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/57108/.
50
Lankford, Maggie E. "Measurement of Thermo-Mechanical Properties of Co-Sputtered SiO2-Ta2O5 Thin Films." University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1627653071556618.