To see the other types of publications on this topic, follow the link: Insulative materials.
Dissertations / Theses on the topic 'Insulative materials'
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 'Insulative materials.'
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
El, Yamani Hamza. "Caractérisation du comportement mécanique de matériaux isolants sous choc." Electronic Thesis or Diss., Bourges, INSA Centre Val de Loire, 2021. http://www.theses.fr/2021ISAB0007.
Full textAbstract:
La réduction des risques, sur des sites Seveso et leurs alentours, face aux sollicitations accidentelles ou malveillantes, passe par la sécurisation des bâtiments aux sollicitations dynamiques de type surpression et impact. L’utilisation d’une isolation par l’extérieur, de type matériau isolant et bardage métallique par exemple, semble une piste intéressante techniquement et économiquement permettant d’allier protection face aux risques technologiques et rénovation énergétique.Dans ce travail, deux matériaux représentatifs des isolants thermiques plastiques et minéraux ont été retenus, une mousse polyisocyanurate et une laine de verre. La caractérisation mécanique de ce type de matériaux complexes et à très faible masse volumique, demeure, dans le contexte de sollicitations dynamiques, largement incomplète à l’heure actuelle et les essais mal maîtrisés.Des essais de compression simple et œdométrique en régime statique sont réalisés et un suivi par imagerie à haute résolution associé à de la corrélation d’images numérique permet d’identifier les propriétés mécaniques, d’observer l’hétérogénéité des déformations et de suivre la propagation de fronts de compaction dans le matériau.Des essais dynamiques aux barres de Hopkinson, complétés d’essais DMA, permettent d’étudier la sensibilité à la vitesse de la réponse et de mettre notamment en évidence une dépendance à la vitesse de la contrainte plateau et une insensibilité à la vitesse de la déformation à la densification. Un suivi par imagerie à haute vitesse associé à de la corrélation d’images numérique permet également d’observer l’hétérogénéité des déformations et de déterminer la célérité du front de compaction dans le matériau.Le comportement mécanique des isolants est reproduit au moyen de lois empiriques ou par assemblage de modèles rhéologiques. Une modélisation simplifiée est proposée pour analyser l’effet potentiel d’un dispositif de protection constitué d’un ensemble bardage et isolant face à une sollicitation dynamique transitoire. Elle montre que si un effet atténuateur est possible, son efficacité va dépendre tout à la fois de la signature de la sollicitation et des caractéristiques physiques et géométriques du système de protectionRisk reduction on Seveso sites, particularly for the protection of industrial buildings in the event of an explosion scenario, is a matter of concern. In the context where the insulation of industrial buildings is becoming more widespread, one solution would be to combine thermal insulation and building protection, by exploiting the absorption capacity of common thermal insulation materials. This solution would be interesting from an economic point of view.The aim of this PhD thesis is to experimentally characterise the mechanical behaviour of two insulating materials commonly used in France: a polyisocyanurate foam and a glass wool. Various devices were used to determine the mechanical behaviour, in particular the Split Hopkinson Pressure Bars device, which allows to characterise the mechanical behaviour at high speed loading.The polyisocyanurate foam was characterised in static and dynamic regimes, in unconfined compression and confined compression. These tests showed a sensitivity to the strain rate of the plateau stress in the material, and showed, by using the digital image correlation technique, the heterogeneity of the deformation in the material. The behaviour of the foam was modelled in two ways: firstly with an empirical law and secondly with a rheological model to simulate a dynamic compression test. The glass wool was characterised in simple static compression, and its behaviour was modelled empirically.The modelling based on empirical laws allowed us to carry out some simple simulations of a dynamic stress of explosion type on a cladding-material-structure assembly. The rheological model, which only concerns the polyisocyanurate foam, was used to identify the viscoplasticity coefficient
2
Costanza, James. "Environmental and Economic Assessment of Reclaimed Polyurethane Panels: The Case of Diverting Decommissioned Cold Storage Panels From Landfills and Recycling Into Three Forms of Insulative Building Materials." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:24078364.
Full textAbstract:
This study investigates the long-term thermal performance of polyurethane insulated cold storage panels and the environmental and economic impact of recycling such panels when taken out of service in lieu of discarding them in landfills.
It is estimated, as of 2015, over 180 million square feet of insulated cold storage panels are manufactured annually in the U.S. The panels are most frequently constructed of closed-cell, low density polyurethane insulation utilizing HCF 245fa and HCF 134a blowing agents containing up to 6 million metric tons (CO2e) of greenhouse gases. The expected operating lifetime of the cold storage panels is 15 years after which time they are primarily discarded in landfills. This practice contributes to the build-up of greenhouse gases in the atmosphere, destroys valuable insulating and building materials and requires landfill space for the solid waste.
Three recycling strategies were investigated as ways to repurpose the discarded framed cold storage panels into new forms of polyurethane insulating materials; repurposed cold storage panels, board stock insulation sheets and blown-in/fill insulation. I used three research methods to quantify the environmental and economic impacts. The first examined the initial and long-term thermal performance of the recycled polyurethane insulation through laboratory testing and extrapolative modeling. The second method was comparative life cycle assessments between the business-as-usual-case of discarding the polyurethane insulation with each of the recycled strategies. Finally, an economic analysis was completed for each recycling strategy to determine the in-use heating & cooling energy savings from the extended life of the recycled insulation.
This research shows recycling of discarded polyurethane cold storage panels provide measurable environmental and economic benefit. First, the productive life of the insulation is extended greatly beyond its initial use period reducing the need for fossil fuels and raw materials to make replacement insulations. Secondly, the high insulating value of the recycled polyurethane maximizes future environmental and economic savings from lower fuel demand in space heating and cooling applications. Thirdly, the majority of the sequestered greenhouse gases continue to be bound in the foam; protecting the environment from the release of global warming gases. Finally, by diverting the cold storage panels from landfills, millions of cubic feet of landfill space are unneeded annually.
3
Rux, Lorelynn Mary. "The physical phenomena associated with stator winding insulation condition as detected by the ramped direct high-voltage method." Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-04042004-112949.
Full text
4
Henriquez, Guerrero Jorge Recarte. "Estudo numerico e experimental sobre vidros termicos." [s.n.], 1996. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263522.
Full textAbstract:
Orientador: Kamal Abdel Radi IsmailDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-07-21T13:16:24Z (GMT). No. of bitstreams: 1 HenriquezGuerrero_JorgeRecarte_M.pdf: 22581929 bytes, checksum: 43baa03f4d321404f2af400b3968e721 (MD5) Previous issue date: 1996
Resumo: Este trabalho apresenta uma abordagem diferente em relação ao conceito de janelas termicamente efetivas, isto é, janelas que reduzem a energia transmitida para dentro ou fora de uma sala. A idéia é usar um painel de vidro duplo preenchido com material de mudança de fase (pcm), cuja temperatura de fusão é determinada por critérios de conforto térmico. A investigação inclui modelamento dos mecanismo de transferência de calor e radiação através do painel, caracterização ótica de janelas convencionais e compostas, e simulação numérica. As amostras incluem vidros comerciais simples de diferentes espessuras e painéis de vidro duplo de diferentes espessuras e espaçamento entre vidros, preenchidos com ar, pcm e finalmente pcm colorido. O modelo é unidimensional transiente e a simulação numérica foi implementada através do método de diferenças finitas na sua forma explícita. Dos resultados da simulação numérica e dos testes de caracterização óticos foram levantadas curvas de ganho térmico, distribuição de temperatura através do painel e evolução da temperaturas da superfícies interna e externas do painel ao longo de um período de 24 horas de forma a verificar o efeito do pcm no desempenho térmico da janela composta
Abstract: This work present a new concept for thermally effective windows, that is windows which reduce the energy transfer to and fIom the internal ambient. This idea behind this concept is to use a pcm fill in the gap between the two glass panels. The fusion temperature of the pcm is selected according to the thermal cornfort criterion. The investigation includes modeling of the mechanisms of heat transfer relevant to the window problem, the thermal radiation through the glass panels, the optical characterization of conventional and composite window configurations and finally the numerical simulation of these configurations. Because of the lack of information on the thermal and optical properties of national gla~s and specially on the composite configuration optical tests were realized to determine the transmittance and reflectivity of simple glass panels of different thicknesses and spacings, air and pcm filled glass panels and finally coloured pcm filled glass panels. The model is a transient one dimensional and the numerical solution is based upon explicit finite difference scheme. the numerical simulations and the optical tests realized allow the determination of the heat gain, the temperature distribution across the glass panels, the outlet and the inlet instantaneous surface temperatures and finally the overall thermal performance of any glass panels including the proposed system
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
5
Le, Gros Mark. "NMRON studies of insulating magnetic materials." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30569.
Full textAbstract:
Selective excitation pulsed NMRON, CW-NMRON and Thermal NMR methods have been used to study the low temperature ⁵⁴Mn nuclear spin-lattice relaxation mechanisms in magnetic insulators.
The selective single and double quantum excitation sequences have been used for the first time in NMRON to obtain single and double quantum rotation patterns, Free Induction Decays, Hahn spin echoes and pulsed T₁ measurements.
Two insulating magnets have been studied; MnCl₂.4H₂O and Mn(COOCH₃ )₂ .4H₂O. In the ⁵⁴Mn-MnCl₂ .4H₂O system the temperature dependence of the ⁵⁴Mn spin-lattice relaxation time at zero field was measured between 35 mK and 90 mK and it was found that the dominant relaxation process between 65 mK and 90 mK is an electronic magnon Raman process and below 65 mK a direct relaxation process dominates.
Single and double quantum Free Induction Decays and Hahn spin echoes have been used to determine the magnitude and nature of the spin-spin relaxation mechanism for ⁵⁴Mn oriented in MnCl₂.4H₂O at zero applied field.
NMRON was observed for the first time in the paramagnetic phase of MnCl₂.4H₂O. The resonance lines are inhomogeneously broadened and 300 kHz wide. A value of <⁵⁴AS>/h=-513.6(3) MHz has been determined for the paramagnetic phase hyperfine coupling constant, and this value has been used to determine the zero point spin deviation of the antiferromagnetic phase.
The field and temperature dependence of the ⁵⁴Mn T₁ was measured for values of field above the spin flop paramagnetic phase transition and a field dependent T₁ minimum was discovered at Ba=2.64 T.
For the ⁵⁴Mn-Mn(COOCH₃) .4H₂O system two ⁵⁴Mn resonances have been observed and the value of the hyper fine coupling constants for the two sites were found to be <⁵⁴AS>/h=-435 (1) MHz for the ⁵⁴Mn1 site and <⁵⁴AS>/h=-478(1) MHz for the ⁵⁴Mn2 site. The high field spin-lattice relaxation behavior has also been investigated and a T₁ minimum at Ba =2.74 T analogous to that observed in MnCl₂ .4H₂O was discovered.
A Hahn echo study of the low field single quantum spin-spin relaxation processes has been performed and anomalous behavior of the spin echo amplitude revealed.Science, Faculty of
Physics and Astronomy, Department of
Graduate
6
Hultberg, Ann-Charlotte, and Emelie Larsson. "Tilläggsisolering inom byggnadsvård." Thesis, Växjö University, Växjö University, Växjö University, Växjö University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-220.
Full textAbstract:
Främsta anledningen till en tilläggsisolering är att det önskas bättre energihushållning i en byggnad. Detta kan göras med olika material och olika tekniker. Inom byggnadsvårdssammanhang förs det en diskussion om de fuktbuffrande materialen är bättre vid tilläggsisolering då de är hygroskopiska än de icke hygroskopiska som är mest frekvent använda i det konventionella byggandet. Denna rapport utvärderar om det finns några dokumenterade fakta som styrker att de hygroskopiska och ekologiska materialen fungerar bättre i byggnadsvårdssammanhang än de icke hygroskopiska. Olika isolermaterial från de två nämnda grupperna jämförs utifrån olika parametrar.
This report evaluates if there are any known facts that support that the hygroscopic and ecologic materials are better in supplement insulation than non hygroscopic. Different kind of insulate materials from these two mentioned groups are compared from without different kind of parameters.
7
Holcroft, Neal. "Natural fibre insulation materials for retrofit applications." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707590.
Full textAbstract:
Improving the thermal performance of existing domestic buildings can have multiple benefits: reducing greenhouse gas emissions, reducing the cost of heating and therefore fuel poverty, improving comfort and health. Solid wall buildings constitute around 30% of UK housing stock, and are among the least efficient. However, the installation of solid wall insulation, while improving thermal performance can significantly affect the moisture balance of the building. This can result in mould growth, which can cause structural damage and lead to health problems for the occupants. This thesis explores the use of Natural Fibre Insulation (NFI) materials for internal solid wall insulation. The hygrothermal properties of a range of NFI materials are characterised in order to assess their potential for retrofit applications. This is followed by large-scale testing, which compares three solid wall insulation systems in controlled conditions, the results of which are used to validate a heat and moisture transfer model to further assess performance. Experimental results showed that the risk of interstitial condensation is significantly reduced by the application of natural fibre insulation in comparison to a conventional rigid foam system. Simulation of a solid wall exposed to climatic conditions for the UK revealed that the relative humidity at the interface between the masonry and insulation layers remained at 69% when internally insulated with hemp-lime and 96% with rigid foam insulation, while average moisture content of the masonry was 48% lower when hemp-lime was used. Field tests were also conducted to determine the thermal performance of two solid walls internally insulated with 80 mm of hemp-lime when exposed to real weather conditions. The thermal conductivity of the hemp-lime was found to be 30% higher than when measured in dry stead-state laboratory conditions due to the high moisture content of the masonry. However, its application still resulted in 66% and 68% reductions in the U-value compared to the uninsulated wall from 2.73 and 2.65 W/m2K to 0.93 and 0.86 W/m2K.
8
Humaish, Hussein Hafudh. "Thermal techniques for characterizing building insulation materials." Thesis, Amiens, 2016. http://www.theses.fr/2016AMIE0034/document.
Full textAbstract:
Cette thèse s'inscrit dans un objectif à long terme de déterminer in situ (et/ou en usage) les propriétés thermiques des matériaux isolants du bâtiment. Notre objectif est de réduire l'écart entre la mesure en laboratoire et la performance réelle des isolants dans les parois de bâtiments. Nous nous sommes fixés deux objectifs principaux au cours de cette étude: 1- Étudier la possibilité d'utiliser la sonde cylindre à choc thermique pour la mesure des caractéristiques thermiques des matériaux isolants du bâtiment. 2- Étudier le comportement thermique d'un isolant en usage en utilisant un montage basé sur le principe de la boite chaude gardée. Cet équipement permet d'effectuer des études dans des conditions climatiques en température et en humidité proches de situations réelles supportées par l'enveloppe d'un bâtiment. Ce travail a permis d'identifier des verrous lors de l'utilisation d'une sonde à choc thermique pour caractériser des matériaux isolants. Il a aussi montré l'intérêt de la boite chaude gardée pour effectuer des études dans des conditions réelles et pour étudier les transferts de chaleur et de masse dans les parois de bâtimentsThis thesis is part of a long-term objective to determine in situ (and / or in use) the thermal properties of building insulation materials. We want to reduce the gap between the laboratory measurement and the actual performance of insulation in buildings walls. We have set two main objectives during this study: 1- To study the possibility of using a non-steady state hot probe for measuring thermal properties of insulants. 2- To study the thermal behaviour of insulation materials in use by using a guarded hot box. Climatic conditions in temperature and humidity close to real situations can be submitted supported by hot and cold cells. This work has shown the interest of using thermal probe to characterize insulating materials. Guarded hot box is also interesting for studies in real conditions and to followheat and mass transfer in buildings walls
9
Meletse, Thabo Frans. "Development of low cost thermal insulating materials." Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/8724.
Full textAbstract:
Includes bibliographical references.The disadvantaged people in South Africa are unfortunate by virtue of their financial status. It was estimated in 1992 that 20 % of the South African population live in informal settlements. The houses in these settlements are found to be very energy inefficient. This study was aimed at developing low cost thermal insulating materials that can be used to increase energy efficiency of the houses in these informal settlements. This was done by firstly studying the properties of thermal insulation materials. Furthermore, common thermal insulating materials in South Africa were studied and evaluated. Only recycled polymeric based materials were examined for selecting the raw materials that were used to investigate the feasibility of the thermal insulating materials from waste material. The experimental work was extended to construct a thermal conductivity rig that was to be used in measuring the thermal conductivity of both the developed and existing thermal insulating materials. The expanded polystyrene obtained from Sagex (Pty) Ltd and polyester obtained from Isotherm (Pty) Ltd. were evaluated and compared to the manufactured recycled polymer slabs and expanded polyethylene foams (EPEF). Expanded polyethylene foam and recycled polymer slab samples were subjected to mechanical and physical testing. A temperature comparison test and thermal conductivity determination were conducted on both the expanded polyethylene foam (EPEF) and recycled polymer slab (RPS) samples. The scanning electron microscope (SEM) was used to reveal the micro-structures of all the developed thermal insulating material samples. The expanded polystyrene and polyester thermal insulating materials were also examined using the SEM. Optical microscopy was only used on RPS samples. It was found in this research, that the properties that govern the viability of thermal insulating materials are: thermal conductivity (k-value), thermal resistance (R-value), combustibility, moisture absorption and the presence of hazardous gases during burning. The temperature comparison test showed that the recycled polymer slab (RPS) and expanded polyethylene foam (EPEF) retards the flow of heat to levels comparable to that of the locally obtained thermal insulation. The comparative cut bar method was found to be relatively cheap to design and it was ideal for the measurement of the thermal conductivity of polymeric based materials. The k-value of all the EPEF samples was measured to be around 0.04 W.m-¹K-¹ and the RPS k-value was found to be 0.05 W.m-¹K-¹. This is attributed to air pockets with lower conductivities values, found within the structure of the polymeric thermal insulating materials. The porous structure is evident from the SEM micrographs of both the EPEF and RPS samples. One grade of expanded polyethylene foam, the SPX80, had accumulated less moisture when moisture absorption was compared with other EPEF samples. The RPS material did have a propensity for absorption of water. The flammability retardant tests have showed that gypsum board has to be incorporated during service for the RPS and SPX80. The mechanical testing results also suggest that both the EPEF and RPS need to be supported when installed in a ceiling, for example.
10
Hoffmann, Ryan Carl. "Electron-Induced Electron Yields of Uncharged Insulating Materials." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/749.
Full textAbstract:
Presented here are electron-induced electron yield measurements from high-resistivity, high-yield materials to support a model for the yield of uncharged insulators. These measurements are made using a low-fluence, pulsed electron beam and charge neutralization to minimize charge accumulation. They show charging induced changes in the total yield, as much as 75%, even for incident electron fluences of <3 fC/mm2, when compared to an uncharged yield. The evolution of the yield as charge accumulates in the material is described in terms of electron recapture, based on the extended Chung and Everhart model of the electron emission spectrum and the dual dynamic layer model for internal charge distribution. This model is used to explain charge-induced total yield modification measured in high-yield ceramics, and to provide a method for determining electron yield of uncharged, highly insulating, high-yield materials. A sequence of materials with progressively greater charge susceptibility is presented. This series starts with low-yield Kapton derivative called CP1, then considers a moderate-yield material, Kapton HN, and ends with a high-yield ceramic, polycrystalline aluminum oxide. Applicability of conductivity (both radiation induced conductivity (RIC) and dark current conductivity) to the yield is addressed. Relevance of these results to spacecraft charging is also discussed.
11
Suebthawilkul, Somkeat. "Application of hollow spheres in insulating castables." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/19164.
Full text
12
Zhang, Lei. "Electrical tracking over solid insulating materials for aerospace applications." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/electrical-tracking-over-solid-insulating-materials-for-aerospace-applications(94086fc5-0ca2-4d12-aa6d-97452d3169d1).html.
Full textAbstract:
The concept of More Electric Aircraft, where is to utilize the electrical power to drive more or all aircraft subsystem instead of conventional combination of pneumatic, hydraulic, mechanical and electrical power, can be recalled to World War II. It has been proven to have more advantages for decades in terms of energy efficiency, environmental issues, logistics and operational maintenance. It can also enhance aircraft weight, volume and battle damage reconfigurability.Thanks to the new electronics technologies and the emergence of new materials, It becomes feasible for high power density electrical power components to drive the majority of aircraft subsystem. However, sustaining the transmission of hundreds of kilowatts of electrical power at low voltages is not feasible owing to the penalties incurred due to high cable weights and voltage drop may become critical. It is very easy to come up with the solution of the increase of voltage. However, higher voltage will introduce other problems such as the reliability of insulation coordination on the aircraft due to the increased probability of electrical discharge. For aircraft designers, it is very important to understand the rules of insulation coordination on the aircraft including determining clearance and creepage distances, and also have a clear investigation of the phenomena and mechanism of electrical discharges. Past research has identified a number of the concerns of operating electrical systems at higher voltages in an aerospace environment, especially for dimensioning of clearances. However, there is little study on dimensioning of creepage distances and relevantly flashover and electrical tracking on solid insulating material surfaces. This thesis firstly discusses the rules for determining clearances and creepage distances. The experimental validation work was done for breakdown in air gap and on the solid insulating material surfaces under dry condition so that some standard recommended values can be evaluated not only with theoretical values such Paschen's law. Suggestions of application of those standards were provided. Secondly, the complex electrical discharge under wet condition on solid insulating material surfaces was discussed. A mathematical model to predict this type of electrical failure -electrical tracking (the electrical discharges on solid insulation materials which will lead to physical damage in the materials) with the consideration of different environmental conditions including air pressure, ambient temperature, and pollution degrees was developed. A series of electrical tracking tests were carried out on organic materials to find out the mechanism of electrical tracking and validate the finding by the mathematic model. Finite element analysis simulations were also conducted to find out the background thermal transfer mechanism to support our explanation of those phenomena of electrical tracking. Different test techniques have ben developed for specific impact factors. Finally, the suggestions for utilization of the standards and feasible test techniques for electrical tracking under wet conditions were provided.
13
Vrána, Tomáš. "Condensation and frost formation in fibrous thermal-insulation materials." Stockholm : Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11632.
Full text
14
Sim, Alec. "Unified model of charge transport in insulating polymeric materials." Thesis, Utah State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3606878.
Full textAbstract:
Presented here is a detailed study of electron transport in highly disordered insulating materials (HDIM). Since HDIMs do not lend themselves to a lattice construct, the question arises: How can we describe their electron transport behavior in a consistent theoretical framework? In this work, a large group of experiments, theories, and physical models are coalesced into a single formalism to better address this difficult question. We find that a simple set of macroscopic transport equations--cast in a new formalism--provides an excellent framework in which to consider a wide array of experimentally observed behaviors. It is shown that carrier transport in HDIMs is governed by the transport equations that relate the density of localized states (DOS) within the band gap and the occupation of these states through thermal and quantum interactions. The discussion is facilitated by considering a small set of simple DOS models. This microscopic picture gives rise to a clear understanding of the macroscopic carrier transport in HDIMs. We conclude with a discussion of the application of this theoretical formalism to four specific types of experimental measurements employed by the Utah State University space environments effects Materials Physics Group.
15
Sim, Alec. "Unified Model of Charge Transport in Insulating Polymeric Materials." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/2044.
Full textAbstract:
Charge transport, charging, and subsequent electrostatic discharge due to interactions with the space environment are primary concerns of spacecraft designers. Developing a physical understanding of the interactions of charge with the multitude of materials that spacecraft are composed of is a critical step in understanding and mitigating both short-term and long-term spacecraft degradation. In particular, the study of charge transport in highly insulating materials is critical as they store charge longer, with higher capacity, and with greater destructive capability than other materials.The Utah State University Materials Physics Group, with the funding of the NASA James Webb Space Telescope project and Rocky Mountain Space Consortium, have developed a complete and consistent theoretical model that predicts short-term and long-term storage capabilities based on physical material parameters. This model is applicable across a wide range of experimental systems designed to test specific behaviors that characterize charging phenomena.Modeling and understanding the complex relationships between the spacecraft and its surroundings are fundamentally based on detailed knowledge of how individual materials store and transport charge. The ability to better understand these effects will help make exploring the edges of the universe more stable, reliable, and economic.
16
Valentini, Francesco. "Development of insulating materials with thermal energy storage/release capability." Doctoral thesis, Università degli studi di Trento, 2022. https://hdl.handle.net/11572/335644.
Full textAbstract:
Nowadays the environmental sustainability and the limitation of the energy consumption of buildings is of substantial importance in order to reduce greenhouse gases emissions and mitigate the consequences of climate change. Thermal energy storage (TES) allows to store thermal energy when available in order to use it when and where necessary. The use of insulating materials with TES capability may results in the compensation of energy absorption peaks caused by air conditioning or by space heating with a consequent reduction of energy consumption and related CO2 emissions. This work aims at the development and characterization of composite materials based on polymeric foams and containing a phase change material providing the TES capability. The production procedures were optimized in order to maximize the quality of the samples and the main properties of the resulting materials were then investigated. Different matrices were considered in this work: thermosetting, thermoplastic and elastomeric ones. As thermosetting matrix, a polyurethane foam was considered: this foam was filled, during the production process, with increasing amounts (from 10 to 40 wt%) of a microencapsulated PCM with a melting point of 24 °C. The addition of the PCM caused the disruption of the regular close cell morphology of the foams with a consequent increase of the thermal conductivity and a reduction of the mechanical properties. On the other hand, the addition of the PCM led to interesting TES properties, measured both through differential scanning calorimetry and infrared thermography (up to 54 J/g). Polyethylene was chosen as thermoplastic matrix and the technology of salt leaching was used to obtain foams without the use of chemical foaming agents. Foams containing different amounts (up to 56 wt%) of a microencapsulated PCM with a melting point of 24 °C were prepared. The addition of the PCM led to a decrease of the connectivity and porosity values of the prepared foams with a consequent decrease of the mechanical properties and increase of the thermal conductivity. Despite the rupture of a certain part of the PCM capsules due to the production process, good TES properties (up to 50 J/g) were measured. Elastomeric foams were prepared using an EPDM rubber as matrix and different foaming agents for the expansion process: foams obtained using two different commercial foaming agents were compared with foams obtained using the salt leaching technique. In the first case, a shape-stabilized PCM was added during the production process, while in the second one the foams were impregnated with a liquid PCM without the necessity of a shape stabilization. Salt leaching foams were able to retain higher PCM loads with respect to foams produced using commercial foaming agents and were therefore characterized by higher TES capability (up to 129 J/g). Infrared thermography tests highlighted that the time required to reach a reference temperature during heating/cooling cycles was three times
longer for samples with a PCM amount of about 55 wt%. These foams evidenced a general decrease of the mechanical properties upon PCM addition. Moreover, a strong influence of the temperature on the mechanical behaviour of these foams was highlighted, with the PCM acting as softener above its melting point and as hardener below. In order to consider practical applications, elastomeric panels made of an ethylene propylene diene monomer (EPDM) rubber filled with a shape stabilized PCM and covered with a nitrile-butadiene rubber (NBR) envelope were prepared. It was possible to verify the absence of leakage, the uniform distribution of the PCM and the influence of temperature on the mechanical properties of the samples. From rheological tests it was also possible to observe the plasticizing effect of the PCM that hindered the vulcanization process of the EPDM/PCM compound. In the second part of this work larger samples were prepared and used for the internal insulation of wood boxes that were subjected to heating/cooling cycles, simulating thus real summer conditions in north Italy. The beneficial effect of the PCM resulted in a consistent reduction of the temperature peak with respect to a reference box insulated with elastomeric panels without PCM. Moreover, the fire behaviour of the produced samples was studied and the effect of the addition of different flame retardants was deeply investigated. The addition of a flame retardant based on ammonium polyphosphate and aluminium diethyl phosphinate as synergistic agents allowed a strong reduction of the peak of heat release rate measured through cone calorimeter tests, with a significant improvement of the fire behaviour. Fire tests allowed also to point out the significant role, in improving the fire performances of the samples, of the interactions between ammonium polyphosphate and the mineral fillers present in the EPDM/PCM compound (clay) and in the envelope (talc, kaolin and silica). A better comprehension of the combustion mechanisms and of the flame retardant efficacy was achieved through the analysis of the combustion residues. Finally, the specific enthalpy of the different systems was evaluated with respect to the cost of the raw materials used in the production stages in order to classify them on the basis of their melting enthalpy and on the economical aspects.
17
Zhang, Hui. "Aging characteristics of solid polymeric materials used for electrical insulation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0018/MQ52685.pdf.
Full text
18
Söderström, David. "Expitaxy, analysis and application of semi-insulating III-V materials /." Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3096.
Full text
19
Wallström, Stina. "Biofilms on silicone rubber for materials outdoor high voltage insulation /." Stockholm : Univ, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171.
Full text
20
Dinkins, Walter Russell. "Electrical characterization of insulating materials using spectral and spatial measurements." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/19416.
Full text
21
Kouadria, Djilali. "The ageing and breakdown characteristics of electrical machine insulation materials." Thesis, University of Brighton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264002.
Full text
22
Goss, Ben. "Degradation and life time prediction of high voltage insulation materials." Thesis, Queensland University of Technology, 2001.
Find full text
23
Sokotun, Zh, and O. Koshelieva. "Evaluation durability of polymeric insulating material of electric cables." Thesis, Київський національний університет технологій та дизайну, 2017. https://er.knutd.edu.ua/handle/123456789/6714.
Full text
24
LORENZATI, ALICE. "Super Insulating Materials for energy efficient buildings: thermal performance and experimental uncertainty." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2711530.
Full textAbstract:
In a global energy-saving policy, Super Insulating Materials (SIMs) represent an effective solution, especially in a world almost saturated with old buildings for which energy refurbishments are needed. Given their extremely low thermal conductivity, they allow reaching an excellent insulation level, with reduced thicknesses. Anyway, they are recent materials or at least recent insulation solutions for the building sector. And as all the new technologies, they bring with them some critical issues to be solved. For example, what is the accuracy of their available thermal conductivity, what are the criteria for their optimal laboratory characterisation, what are their actual thermal performances in situ and how long is their durability and what is their practical convenience still remain open questions.
The aim of this research was to provide an answer to these questions, although sometimes in a preliminary way.
Therefore, the thermal properties of SIMs (and in particular of the Vacuum Insulation Panels, since, between the SIMs they are the most performing and the most critical solution) were explored at different levels, from the material/panel scale to the building scale.
SIMs are actually laboratory tested using traditional experimental apparatuses, such as the Heat Flow Meter (HFM) and the Guarded Hot Plate (GHP), and in accordance with as traditional standard, developed for the most common insulating material. Indeed, at the first stage of this research, the applicability of the current methodologies was extensively verified, with an in-depth analysis of the obtainable measurement uncertainties. The uncertainty assessment was performed in three different ways, to analyse the various scenarios that may occur: a theoretical standard based uncertainty evaluation, and both the Type A and Type B experimental uncertainty assessment.
Once defined the best criteria for a proper evaluation of the SIMs thermal properties, they were experimentally characterised, considering the different parameters which could have some effects on their thermal behaviour (different thicknesses, average testing temperature, temperature difference, ageing conditions and so on).
In practical applications of the VIPs, they must be assembled one to each other: innovatively, both the HFM and GHP apparatuses were also used for the evaluation of the linear thermal transmittance of the thermal bridges that occur in case of VIPs assemblies. The investigation performed at the material/panel level were then repeated at the component scale, to evaluate the variability and the measurement uncertainty of the linear thermal transmittance.
The so defined thermal performances represented a reliable pool of input data for the dynamic hygrothermal simulations at the building scale. The goals were the evaluation of the energy efficiency of building insulated with SIMs and the prediction of the durability of these materials (considering different severities of the building envelope component boundary conditions).
The outputs of the numerical simulations were then coupled with an economic analysis, to evaluate the convenience of VIP insulation, in terms of discounted pay-back period.
25
Keenan, Patrick Joseph. "Thermal insulation of wet shielded metal arc welds." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37182.
Full textAbstract:
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Sciences & Engineering, 1994.Includes bibliographical references (leaf 55).
by Patrick Joseph Keenan.
M.S.
Nav.E.
26
Lopez, Hurtado Pablo. "Development of novel building insulation materials, incorporating cellulose and biobased additives." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0061.
Full textAbstract:
La ouate de cellulose utilisée pour l’isolation est fabriquée à partir de fibres de papier broyé, traitées avec des additifs minéraux agissant comme agents ignifuges et antifongiques. La conductivité thermique du matériau final est aux alentours de 0,04 W/m.K, ce qui est comparable à la laine de verre, avec l’intérêt d’être fabriqué à partir de matériaux recyclés, représentant un taux d’énergie grise beaucoup plus faible. Le mode de mise en oeuvre par voie humide de la ouate de cellulose a plusieurs avantages par rapport à la voie sèche. Le fait que les fibres de cellulose se rigidifient avec l’eau, empêche le tassement du matériau, qui peut engendrer des ponts thermiques dans l’enveloppe du bâtiment. Par contre, la durée de séchage peut être très longue et variable selon le dosage utilisé et les conditions ambiantes d’application. Ce projet de recherche vise à trouver l’additif idéal permettant d’accélérer le séchage tout en conservant une bonne cohésion du matériau et le maintien de ses propriétés isolantes. Deux types de ouate de cellulose utilisés en isolation ont été caractérisés. Ils ont montré des différences de composition chimique, granulométrie et morphologie. L’influence de leurs caractéristiques physiques telles que la rétention d’eau, les isothermes d’adsorption d’eau et les proportions d’eau libre et liée sur le séchage du matériau final a été mise en évidence. Du point de vue de la mise en oeuvre, il a été démontré que le dosage en eau avait un impact important sur les propriétés finales du matériau. La densité, la résistance en compression et la conductivité thermique augmentent avec le dosage en eau. Un minimum de 14 kPa pour le module de compression a été défini comme le seuil de résistance permettant d’éviter le tassement. Ces propriétés ont été comparées avec celles de la ouate de cellulose compactée à sec et les résultats ont montré la forte influence de la rigidification et de la fermeture des pores du matériau. Deux voies ont été envisagées pour résoudre le problème du temps de séchage : l’ajout d’additifs aux propriétés adhésives permettant de réduire la quantité d’eau introduite en renforçant la cohésion de l’isolant, et l’ajout d’additifs permettant de modifier la tension de surface pour faciliter le départ de l’eau. Les additifs biosourcés potentiels ont été caractérisés à différentes concentrations et classés selon leur viscosité et leur pouvoir collant. Malheureusement plusieurs additifs ont dû être rejeté car ils présentaient un couple « propriété adhésive/pompabilité » non adapté. Une gamme de tensioactifs a également été testée par rapport à leurs tensions de surface. Les formulations pompables ont étés caractérisées par rapport à leurs temps de séchage, résistance en compression et conductivité thermique. Les additifs qui ont montré des contributions positives sur le séchage sont les lignosulfonates et le tensioactif cationique CTAB. L’influence de ces deux additifs a ensuite été étudiée avec un modèle numérique à travers le logiciel WUFI en prenant en compte l’impact sur le séchage, la météo, le dosage liquide et l’épaisseur de l’isolant. Les conditions optimales ont été définies. Le lignosulfonate s’est avéré être l’additif le plus efficace. Une première évaluation de la performance des nouveaux isolants en termes de résistance au feu et à la moisissure a été réalisée et des indications pour la suite de l’étude ont été proposéesCellulose insulation is manufactured from recycled paper fibres, treated with mineral additives acting as flame retardants and antifungals. Its consistency is similar to cotton wool. The fibres are sold in bulk to be blown into the walls and attics. Its thermal conductivity is around 0.04 W/m.K, which is comparable to glass wool, but it is made with recycled materials and has much lower embodied energy levels. It can be either blown dry or sprayed with water. The wet spray method for cellulose insulation has several benefits compared to the dry process. Since the cellulose fibres become rigid after drying, it prevents the compaction of the material thus avoiding thermal bridges in the building envelope. However, the time to reach the dry state may be very long and variable depending on the dosage used and the environmental conditions of application. There are many bio-based additives that can contribute to the reduction of this period and improve the cohesion of the material. This research project aims to find the optimal additive for this application while retaining the favourable properties of the insulating material. Two cellulose types have been characterized with regards to the properties of the fibres to determine their performance with water. Both samples showed differences in chemical composition, grain size, and morphology. The values of water retention, water adsorption isotherms and the proportions of free and bound water have been factors which have shown an influence on the drying of the insulation. Density, compressive strength, and thermal conductivity increased with moisture dosage. A minimum of 14 kPa for the compression module was defined as the resistance threshold to avoid settling. These properties were compared with those of the cellulose insulation compacted to dryness and the results showed the strong influence of the stiffening and pore closing process upon drying, on these properties. Potential bio-based additives were classified and characterized with regards between concentration, viscosity, and adhesive strength. A relationship between these parameters was established. Most showed Newtonian behaviour at low concentrations, with some non- Newtonian concentrations having a pumpable viscosity. Unfortunately several additives which showed good adhesive properties were too viscous and vice versa. A range of surfactants were also considered. Sprayable formulations were characterized with respect to their drying time, compressive strength and thermal conductivity. Additives which have shown positive contributions drying are the lignosulfonate and the cationic surfactant CTAB. The influence of these additives on drying, with varying weather, liquid dosage and thickness of insulation was defined with a numerical model through the WUFI software. Optimal conditions in which the lignosulfonate additive is more effective have been defined. A first assessment of the performance of new formulation in terms of fire and mould was made and indications for the continuation of the study of the material were formalized
27
Widenor, Ross. "An Investigation of Contact Electrification and Triboelectric Charging in Insulating Materials." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1364229648.
Full text
28
Abdul, Karim Aniza. "The interaction of keV cluster and MeV ions with insulating materials." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/808312/.
Full textAbstract:
Secondary ion mass spectrometry (SIMS) is a well-known surface analysis technique with numerous applications in materials science. In recent years various types of primary ion beams have emerged to improve SIMS for analysing polymers, organic semiconductors and biological materials. keV cluster ions have given an improvement in producing higher secondary ion yields, reduced topography and reduced interface mixing while MeV SIMS has proven to be better in certain cases especially at desorbing higher mass molecules and has the ability to perform measurements at ambient pressure. This has generally driven the study to understand the interaction between keV cluster ions and MeV ions with insulating materials from both a modelling and an experimental perspective. A simple Monte Carlo model describing the desorption of a molecular solid under keV cluster and MeV ion bombardment is described. The model employs a conical ejection pattern, which has been suggested to be applicable for keV cluster and MeV ions impinging on molecular solids. The conical ejection region is combined with a cylindrical fragmentation region to predict the sputtering behaviour of molecular materials. Molecular dynamics simulations are used to back up this model. The model provides information about surface roughness induced by the process as well as the fragmentation build up during a prolonged sputtering process. This model is expanded to multi-layered systems and has produced some insight on the depth resolution of the analysis. Comparison studies between the model and experiments are also presented with polymer films analysed by a 10keV C60+ time-of-flight (TOF) SIMS. These results are found to compare favourably with each other.
29
Latif, Eshrar. "Hygrothermal performance of hemp based thermal insulation materials in the UK." Thesis, University of East London, 2013. http://roar.uel.ac.uk/3454/.
Full textAbstract:
This thesis explores the hygrothermal performance of hemp insulation in the context of the United Kingdom. The key objectives of this investigation were to assess the heat and moisture management capacities of hemp insulations in two constructions typical to the UK, of timber frame and solid brick walls and to put the findings of the assessment into the greater context of conventional insulation materials by comparing hemp insulation’s performance with that of stone wool. The assessments were performed by means of laboratory-based experiments, in situ experimental monitoring and computer based numerical hygrothermal simulations. The most important finding during the laboratory-based experiment is that, in high relative humidity, the likelihood and frequency of interstitial condensation is higher in stone wool insulation than in hemp insulation. In terms of the material properties, one of the key findings during the laboratory-based experiment is the high level of moisture buffering capacities of hemp insulations, and therefore their potential in managing moisture in buildings. The in situ assessment of hygrothermal properties of hemp and stone wool insulations confirms the findings of the laboratory based experiments of the corresponding moisture management capacities of these two insulation materials. Parametric analysis of the in situ data shows that mould spore germination is possible in the insulations in vapour open walls although the visual observation has not confirmed the outcome of this analysis. In terms of thermal conductivity, the important finding is that the equivalent thermal conductivity of hemp and stone wool insulations are always equal or below the manufacturers’ declared thermal conductivity values. Long-term hygrothermal performances of hemp and stone wool insulation in timber frame and solid brick walls have been also assessed using a numerical hygrothermal simulation tool (WUFI). As far as the WUFI predictions are concerned, the application of the hemp or stone wool insulation on solid brick wall does not seem to be feasible with reference to condensation and mould growth in the insulations.
30
Mahmood, Salih Qasim. "Behavior of Lap Shear Connections with Thermally Insulating Filler Plates." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/4159.
Full textAbstract:
This research consists of experimental load tests and numerical simulations of structural steel connections with various filler materials to study the effect of non-steel fillers on the connection strength. Non-steel fillers are used in the steel connections to provide thermal insulation by reducing thermal bridging. Eight specimens having steel and polypropylene filler plates of various thicknesses were tested in the laboratory. The collected data were compared to a Finite Element Analysis (FEA) using ABAQUS to validate the numerical results. After validation, three parametric studies were conducted using ABAQUS to provide insight into general behavior of connections with a variety of fillers that could be used as thermal breaks. In addition, an extreme case of having air gaps instead of alternative fillers was also considered.
The Research Council on Structural Connections (RCSC 2014) suggests a reduction in the bolt shear strength when undeveloped fillers with a thickness of more than 0.25 inch are used while using any non-steel material is prohibited due the limited research available.
Most research studies have investigated the mechanical behavior of thermal breaks in either end-plate moment connections or slip-critical connections. No data is available for thermal breaks in bearing-type connections up to failure.
This research aims to study the effects of filler material properties such as modulus of elasticity and strength on bolt strength, as well as investigate whether the current equation in RCSC 2014 is applicable for alternative filler materials like polypropylene that has less than 0.5% of the steel modulus of elasticity and less than 10% of steel strength.
31
Alam, Mahmood. "Development of vacuum insulation panel with low cost core material." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/11658.
Full textAbstract:
Buildings consume around half of the UK's total energy consumption and are responsible for almost 50% of UK's total carbon dioxide (CO2) emissions. Use of high thermal resistance insulation in buildings is critical to save the substantial amounts of space heating energy lost through building fabric. Conventional building insulation materials have higher thermal conductivity values ranging from 40 mWm-1K-1 (Glass fibre) - 26 mWm-1K-1 (Polyurethane foam) and require larger thicknesses to achieve stringent building regulation requirements which may not be feasible due to techno-economic constraints. Vacuum Insulation Panel (VIP) is a relatively new insulation for building applications that offers 5-8 times higher thermal resistance and can achieve significant space savings in buildings. VIPs are produced as a rigid panel comprising inner core board laminated in an outer high barrier envelope under evacuated conditions (< 5mbar). However, the main challenge for large scale acceptance of VIPs in building applications is their higher cost. VIPs have been shown to have an approximately 10 times longer payback compared to conventional EPS insulation due to their high initial cost. Expensive materials currently being used for VIP manufacturing such as fumed silica contribute to high cost of VIPs and it is critical to identify alternative low cost materials for VIP components to overcome the challenge of high cost. The aim of this thesis was to develop an alternative low cost material and investigate its suitability for use as VIP core. Expanded perlite, a low cost material was identified as a replacement of expensive fumed silica in a VIP core. Composite samples containing expanded perlite, fumed silica, silicon carbide (SiC) and polyester fibres were developed by dry mixing of the constituents in different mass ratios and their different properties were experimentally measured to identify optimum composition of composite. Gaseous thermal conductivity at different pressures was calculated from the pore size data obtained using Mercury Intrusion Porosimetry (MIP), gas adsorption and electron microscopy. Radiative conductivity of composite samples was measured using Fourier Transform Infrared (FTIR) to ascertain the opacifying effect of expanded perlite and opacifier (SiC). Centre of panel thermal conductivity of core boards of size 100mm x 100mm made of composite material at atmospheric pressure was measured by using a small guarded hot plate device. Average pore diameter values of expanded perlite decreased with the partial filling of fumed silica aggregates and was found to be in the range of 150-300 nm yielding lower gaseous conductivity values of 1.2-2.1 mWm-1K-1 at 100mbar and became negligible upon further decreasing pressures below 10 mbar. Core boards made of optimised composite containing 30% expanded perlite and 50% fumed silica along with SiC and polyester fibres was found to achieve centre of panel thermal conductivity of 28 mWm-1K-1 at atmospheric pressure and the average radiative conductivity of 0.67 mWm-1K-1 at 300K with its gaseous thermal conductivity at 1 mbar being 0.016 mWm-1K-1. According to the results of the thesis VIP prototypes consisting of core made with optimised composite consisting (50 mass% of fumed silica, 30 mass% of expanded perlite along with 8 mass% of fibre and 12 mass% of SiC) yielded centre of panel thermal conductivity of 7.4-7.6 mWm-1K-1 at pressure of 0.53-0.64 mbar. Opacifying properties of expanded perlite were observed and quantified. Expanded perlite reduced the radiative conductivity of the composite requiring smaller quantities of high density opacifiers such as SiC. For sample containing no expanded perlite, average radiative conductivity was calculated to be 1.37 mWm-1K-1 and radiative conductivity values decreased to 1.12 mWm-1K-1, 0.67 mWm-1K-1, 0.63 mWm-1K-1 and 0.50 mWm-1K-1 with mass ratio of expanded perlite 20%, 30%, 40% and 60% respectively. It was concluded that the solid conductivity of prototypes VIPs was 1.8-2 times higher compared to those of commercially available VIPs and is the main reason for higher centre of panel thermal conductivity.
32
Condò, Marco. "Electrical characterization of innovative insulating materials for HVDC energy transmission cable systems." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
La tesi si è svolta nel corso di uno stage di quasi nove mesi all'interno del laboratorio elettrico di alta tensione del reparto R&D di Prysmian, leader mondiale dei sistemi elettrici in cavo. La tesi si è articolata nelle fasi seguenti:
1) analisi dei fondamenti teorici dei sistemi elettrici in cavo ad alta tensione in corrente continua (HVDC);
2) caratterizzazione elettrica di materiali isolanti innovativi per lo sviluppo di sistemi in cavo HVDC. Più in dettaglio tale caratterizzazione è consistita nelle fasi seguenti:
a) progettazione e/o realizzazione dei set-up di prova;
b) esecuzione delle prove di conducibilità elettrica su provini piani di materiale isolante costituiti da diverse mescole candidate per la realizzazione di cavi modello nella seconda parte della caratterizzazione (vedi seguito);
c) elaborazione dei dati delle prove di cui al punto b) per ricavare i parametri σ0, α e β della conducibilità di ogni mescola isolante testata - e quindi l’andamento della conducibilità delle mescole in funzione della temperatura e del gradiente elettrico – così da selezionare le mescole migliori per la realizzazione dei cavi modello (cavi in scala ridotta con dimensioni standardizzate realizzati ai fini di prove di sviluppo);
d) esecuzione delle prove di tenuta in AC sui cavi modello selezionati;
e) esecuzione delle prove di rigidità ad impulso atmosferico su cavi modello;
f) esecuzione delle prove di stabilità termica su cavi modello.
I risultati di tutte le prove condotte hanno consentito di determinare quali fossero, tra tutte le mescole prese in esame, le più performanti dal punto di vista elettrico.
33
Chitela, Yuvaraj R. "Sustainable Ecofriendly Insulation Foams for Disaster Relief Housing." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984180/.
Full textAbstract:
Natural disasters are affecting a significant number of people around the world. Sheltering is the first step in post-disaster activities towards the normalization of the affected people's lives. Temporary housing is being used in these cases until the construction of permanent houses are done. Disposal of temporary housing after use is leading to a significant environmental impact because most of them are filled with thermally insulative polymer foams that do not degrade in a short period. To reduce these problems this work proposes to use foams made with compostable thermoplastic polylactic acid (PLA) and degradable kenaf core as filler materials; these foams are made using CO2 as blowing agent for insulation purposes.
Foams with PLA and 5%, 10% and 15% kenaf core were tested. Different properties and their relations were examined using differential scanning calorimetry (DSC), thermal conductivity, mechanical properties, scanning electron microscopy (SEM), x-ray μ-computed tomography (μ-CT) and building energy simulations were done using Energy Plus by NREL. The results show that mechanical properties are reduced with the introduction of kenaf core reinforcement while thermal conductivity display a noticeable improvement.
34
Abo, Madyan Omar. "Functionalisation of clay aerogel composites for applications in construction." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/17455.
Full textAbstract:
Clay aerogels are relatively a new class of materials with number of merits suitable for many applications in various industrial sectors. With the current mandate to utilise environmentally friendly materials to produce functional materials, clay aerogels provide an attractive potential green solution to overcome thermal issues in construction. However for it to be effectively used as an insulation material, research work is required to address several critical issues and setbacks: the first of these is poor mechanical properties highlighted in the literature as its main weakness; the second is there extremely high hydrophilic and hygroscopic nature identified as the main research gap, which not only can cause a significant increase in thermal conductivity but also can disintegrate the aerogels. This thesis investigates and develops novel methodologies to overcome the associated setbacks through comprehensive characterisation and better understanding of mechanisms of formulation, architecture, behaviour and corresponding performance of clay aerogel constituents and composites: (I) The anisotropic structure of the aerogel was thoroughly investigated and its influence on properties was established; (II) By adjusting and tuning the mixing temperatures, the compressive modulus was enhanced by more than 7 folds; (III) Ultrasonic technologies were used to prepare organoclay- polyvinyl alcohol aerogel composites with 40% less moisture absorption in addition to lower thermal conductivity; (IV) Implementing organosilanes and isocyanates to prepare clay-PVA aerogels resulted in an effective method to reduce the moisture absorption by more than 40% with a 6 fold increase in compressive modulus; (VI) soluble water repellent was incorporated to prepare hydrophobic aerogel composites with contact angles of 140°; and (VII) Organosilanes and isocyanates are combined with a water repellent to generate highly functional clay aerogel composites. Overall this thesis paves the way for the industrialisation of functional clay-aerogel insulation materials for construction and other sectors.
35
Khan, Amir. "Vibro-acoustic products from re-cycled raw materials using a cold extrusion process : a continuous cold extrusion process has been developed to tailor a porous structure from polymeric waste, so that the final material possesses particular vibro-acoustic properties." Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/4289.
Full textAbstract:
A cold extrusion process has been developed to tailor a porous structure from polymeric waste. The use of an extruder to manufacture acoustic materials from recycled waste is a novel idea and the author is not aware of any similar attempts. The extruder conveys and mixes the particulates with a reacting binder. The end result is the continuous production of bound particulates through which a controlled amount of carbon dioxide gas that is evolved during the reaction is used to give the desired acoustic properties. The cold extrusion process is a low energy consuming process that reprocesses the post manufacturing waste into new vibro-acoustic products that can be used to meet the growing public expectations for a quieter environment. The acoustical properties of the developed products are modelled using Pade approximation and Johnson-Champoux-Allard models. Applications for the developed products are widespread and include acoustic underlay, insulation and panels in buildings, noise barriers for motorways and railway tracks, acoustic insulation in commercial appliances and transport vehicles.
36
Castrovilli, Matteo. "Characterization of the dipole processes of insulating materials used in aeronautical cables." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textAbstract:
The studies of this thesis are focused on aeronautic Polymers materials and their dielectric properties, in order to analyze the relaxation times for the materials of interest under an applied electric field, and in order to increase the work operations of the Novocontrol dielectric spectroscopy measurement machine available in the LAPLACE laboratory. In this context, the research team DSF in collaboration with MDCE, from LAPLACE laboratory, has developed in 2019 a numerical model taking into account the polar mechanisms of the polymer insulators used in the aeronautic industry. However, this theoretical model, is not yet validated. Therefore the aim of this thesis, is to make it possible to validate this theoretical model, then by a series of measurements with dielectric spectroscopy(D.S.) for different materials of interest, different frequencies and temperatures; the measurements consist on the measuration of the phase difference between current and voltage applied to the samples, in order to calculate the permittivity values under different working conditions. The permittivity trend is therefore analyzed to find the polar relaxation under thermoelectrical stresses, and the model will then have to calculate the current density (and from the current density is directly calculated the dissipated energy) of the measured data with dielectry spectroscopy, and the validation will be done if the future measurement values of the current density correspond to the calculated one by the model. For this reasons, the main part of the work for this thesis consist in measurements trought the dielectric spectroscopy (using the following polar materials: Polyimide(PI) and PTFE ) under different working conditions and analyze the results in order to evidence polarization phenomena, because the purpose of this part of the validation process is to have the better polar relaxation data for the future work.
37
McLaggan, Martyn Scott. "Novel fire testing frameworks for Phase Change Materials and hemp-lime insulation." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/15896.
Full textAbstract:
Modern buildings increasingly include the usage of innovative materials aimed at improving sustainability and reducing the carbon footprint of the built environment. Phase Change Materials (PCMs) are one such group of novel materials which reduce building energy consumption. These materials are typically flammable and contained within wall linings yet there has been no detailed assessment of their fire performance. Current standard fire test methods provide means to compare similar materials but do not deliver knowledge on how they would behave in the event of a real fire. Thus, the aim of this thesis is to develop a novel testing framework to assess the behaviour of these materials in realistic fire scenarios. For PCMs, a flammability study is conducted in the bench-scale cone calorimeter to evaluate the fire risk associated with these materials. Then, micro-scale Thermogravimetric Analysis (TGA) is used to identify the fundamental chemical reactions to be able to confidently interpret the flammability results. Finally, intermediate-scale standard fire tests are conducted to evaluate the applicability of the bench-scale results to realistic fire scenarios. These take the form of modified Lateral Ignition and Flame spread Test (LIFT) and Single Burning Item (SBI) tests to understand flame spread and compartment fires respectively. Finally, a simplified method to combine this knowledge for use in building design is proposed. This method allows the balancing of potential energy benefits with quantified fire performance to achieve the specified goals of the designer. Hemp-lime insulation is a material which has also becoming increasingly popular in the drive towards sustainability. The porous nature of the material means that smouldering combustions are the dominant reaction mode but there is currently no standardised test method for this type of behaviour. Thus, hemp-lime materials also represent an unquantified risk. The work in this thesis defines a simple, accessible and economically viable bench-scale method for quantifying the fire risk associated with rigid porous materials. This is applicable for both downward opposed flow and upward forward flow smoulder propagation conditions. The behaviour is then interpreted using micro-scale thermogravimetric analysis to understand the underlying pyrolysis and oxidation reactions. Designers can utilise this framework to quantify the smouldering risk associated with hemp-lime materials to enable their usage in the built environment. The holistic fire risk assessment performed in this thesis has quantified the behaviour of PCMs and hemp-lime insulation applicable to realistic fire scenarios. The simplified design method empowers designers to be able to realise innovative buildings through fundamental understanding of the fire behaviour of these materials. The outcomes of this thesis allow designers to mitigate the fire risk associated with these materials and achieve optimised engineering solutions. Furthermore, the novel fire testing frameworks provide the economically viable means to assess the fire performance of future PCMs and hemp-lime products which ensures lasting relevance of this research in the future.
38
Ghorbani, Hossein. "Characterization of Conduction and Polarization Properties of HVDC Cable XLPE Insulation Materials." Licentiate thesis, KTH, Elektroteknisk teori och konstruktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180809.
Full textAbstract:
Since its first introduction in 1998, extruded direct current (DC) cable technology has been growing rapidly leading to many cable system installations with operation voltages up to 320 kV. Cable manufacturers invest heavily on technology development in this field and today extruded DC cable systems for operation voltages as high as 525 kV are commercially available. The electrical field distribution in electrical insulation under DC voltage is mainly determined by the conduction physics, therefore a good understanding of the DC conduction is necessary. In case of Cross-linked Polyethylene (XLPE) insulation, the presence of the peroxide decomposition products (PDP) is believed to influence its electrical properties. The PDP are volatile and therefore they may diffuse out of the samples during sample preparation and testing. Besides, the morphology of the XLPE is known to evolve over time even at moderate temperatures. Since the material may change during preparation, storage and even measurement, the procedure during all stages of the study should be chosen carefully. In this work, the physics of the dielectric response and conduction in XLPE is briefly discussed. The existing measurement techniques relevant to characterization of DC conduction in XLPE insulation materials are reviewed. The procedure for high field DC conductivity measurement is evaluated and recommendations for obtaining reproducible results are listed. Two types of samples are studied, i.e. thick press molded samples and thick plaque samples obtained from the insulation of in-factory extruded cables. For press molded samples, the influence of the press film used during press molding and the effect of heat-treatment on the electrical properties of XLPE and LDPE are studied. High field DC conductivity of XLPE plaque samples is measured with a dynamic electrode temperature to simulate the standard thermal cycles. Investigations show that using PET film during press molding leads to higher apparent DC conductivity and dielectric losses when compared to using aluminum foil. The influence of heat-treatment is different depending on the press film. High field DC conductivity measurements and chemical composition measurement of samples obtained from the cable insulation are in good agreement with the results obtained from the full scale measurements. Finally a non-monotonic dependence of apparent DC conductivity to temperature of some samples pressed with PET film is discovered which to the author’s best of knowledge has not been previously reported in the literature.Sedan det första införandet i 1998 har extruderad likspänning (DC) kabeltekniken vuxit snabbt och har lett till många existerande kabelsysteminstallationer med driftspänningar upp till 320 kV. Kabeltillverkare investerar kraftigt i teknikutveckling inom detta område och idag finns extruderade DC kabelsystemen tillgängliga för driftspänningar så höga som 525 kV. Elektrisk fältfördelning i isolationsmaterial under hög DC spänning, beror framförallt på materialets elektriska ledningsfysik, därför är en bra förståelse av DC ledningsförmåga nödvändig. Isolationsmaterial av tvärbunden polyeten (PEX) innehåller tvärbindningsrestgaser som tros påverka materialets elektriska egenskaper. Restgaserna är flyktiga och kan diffundera bort från proven under preparering och mätning, även under måttliga temperaturer. PEX materialets morfologi ändras även med tiden. Med tanke på att materialet kan ändras under provpreparering, lagring och även vid mätning, så måste samtliga steg ovan väljas mycket försiktigt. I detta arbete diskuteras grundläggande fysik för dielektrisk polarisering och ledningsförmåga i PEX-isolation tillsammans med granskning av existerande mätteknik relevant för karakterisering av ledningsförmåga i PEX. Procedurer för mätning av DC ledningsförmåga under höga elektriska fält är undersökta och rekommendationer för reproducerbar mätningar är framtagna. Två typer av prover är studerade, tjocka pressade plattor och tjocka plattor som ursvarvats från kommersiell tillverkade högspänningskablar. För pressade plattor, studerades effekten utav press-filmens påverkan på de elektriska egenskaperna hos PEX och LDPE. Påverkan av värmebehandling på DC ledningsförmåga av PEX plattor studerades också. Slutligen studerades DC ledningsförmåga av PEX och LDPE plattor under höga DC fält och med dynamisk temperatur på elektroderna med syftet att efterlikna standardvärmecyklingar. Undersökningarna visade att användningen av PET filmer under pressning av plattor ledde till högre DC ledningsförmåga och högre dielektriska förluster i proven i jämförelse med användning av aluminiumfolie. Påverkan utav värmebehandling är olika beroende på typ av film som används pressningen. Det finns en stark korrelation mellan resultaten från DC konduktivitet och kemisk komposition mätningar från plattor skaffat från kabelisolation och resultaten från fullskaliga kabelmätningar. Slutligen, upptäcktes ett icke monotont beroende av DC konduktivitet hos PEX och LDPE plattor på temperatur som tidigare inte rapporterats i litteraturen.
QC 20160125
39
Kyriakides, Steven Alan. "Characterization of Shear Strengths and Microstructures for Solid Rocket Motor Insulation Materials." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35974.
Full textAbstract:
As advances in solid rocket technology push rocket motors to more extreme operating speeds and temperatures, it becomes increasingly important to have well-designed material systems capable of surviving these harsh conditions. One common component in these systems is the use of a fiber- and particle-reinforced EPDM insulation layer between the motor casing and the solid fuel to shield the casing from the temperatures of the burning fuel and from the high velocity of gas particles traveling within the motor. This work studies several insulation materials to determine which exhibits the highest shear strength after being charred. Double-notch shear test specimens of three materials, ARI-2718, ARI-2719, and ARI-2750, were charred and tested to measure the failure strength of each charred material. The ARI-2750 showed the highest shear strength when loaded along the material orientation, but the ARI-2719 was strongest when transversely loaded. The strength measurements for ARI-2750 were highly sensitive to loading direction, unlike ARI-2718 and ARI-2719. Extensive scanning electron microscopy to identify correlations between shear strength and microstructure revealed that the amount of fiber orientation and amount of residual matrix material may have significant impacts on charred shear strength in these materials.Master of Science
40
Conceição, Rafael Novaes da 1978. "Avaliação de nova resina contendo nanopartículas para aplicação na isolação elétrica de barras estatóricas = Evaluation of a new resin containing nanoparticles for application in the electrical insulation of stator bars." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266020.
Full textAbstract:
Orientador: João Sinézio de Carvalho CamposDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-27T19:06:13Z (GMT). No. of bitstreams: 1 Conceicao_RafaelNovaesda_M.pdf: 10111957 bytes, checksum: 9168b5514bd29d6ead99888af5052aab (MD5) Previous issue date: 2015
Resumo: É bem conhecida a necessidade de energia elétrica para o bem estar e desenvolvimento tecnológico da população em nosso planeta. Ao lado dos avanços científicos de novas tecnologias para geração, existem interesses na melhoria do transporte da energia. Dentre estes se encontram materiais para isolação elétrica de barras estatóricas, quer sejam para melhorar a isolação ou mesmo para reduzir custos. Assim, o presente trabalho visa apresentar resultados da aplicação de uma nova resina epóxi bisfenólica (DGEBF) (RN) à base de nanopartículas de sílica e comparar suas propriedades com a resina epóxi bisfenólica (DGEBA) (RE), atualmente utilizada para a isolação de hidrogeradores. Neste sentido, fabricaram-se protótipos de barras estatóricas, destinadas a hidrogeradores, sendo as resinas impregnadas em sistema VPI (Vácuo-Pressão-Impregnação) e avaliaram-se as propriedades físico-químicas pelas técnicas de viscosimetria, TGA, DSC, MEV e EDS. As propriedades elétricas foram avaliadas pelas técnicas de fator de dissipação (tan delta), descargas parciais, envelhecimento acelerado (VET) e tensão de ruptura. Dentre os resultados das propriedades físico-químicas pode-se comprovar um aumento inicial de três vezes o valor de viscosidade para resina RN em comparação com RE. Entretanto, não houve detrimento das características dielétricas em função da viscosidade, o que foi comprovado através dos resultados de tan delta e VET. Obteve-se um valor de Tg de 116°C e 145°C para RN e RE, respectivamente, o que limitaria a aplicação da resina em geradores por estar abaixo da temperatura de operação. Dentre os resultados dos testes elétricos para as resinas observou-se que: (i) o fator de dissipação e de envelhecimento são praticamente os mesmos para ambas as resinas; (ii) o valor de tip-up resultaram em 0,014 % para RE e 0,020 % para a resina RN, sendo que a norma EN 50209 exige que seja inferior a 0,25% e (iii) a estimativa do tempo de vida útil obtida foi de cerca de 40 anos para os dois tipos de resina, o que é aplicável para maioria dos enrolamentos em operação. Neste sentido sugere-se que a resina RN pode ser uma boa alternativa a resina RE, com um desempenho elétrico equivalente, desde que ajustadas suas condições de processamento e temperatura de aplicação
Abstract: It is well know the demand of electrical energy for the wellbeing and technological development of the population in our planet. Among the scientific development of new technologies for generation, are interests to optimize the energy transport. Among them are materials for electrical insulation of stator bars, whether for improving the insulation or even to reduce the costs. Therefore, the present work aim to present the results of the employment of a new bisphenolic epoxy resin (DGEBF) (RN) containing silica nanoparticles and compare its properties with the bisphenolic epoxy resin (DGEBA) (RE) currently used for the insulation of hydrogenerators. In this context, it was manufactured prototype stator bars, designed for hydrogenerators, being the resins impregnated through VPI (Vacuum-Pressure-Impregnation) system and their physicochemical properties evaluated with the technics of viscosimetry, TGA, DSC, MEV and EDS. The electrical properties were evaluated with the tests of dissipation factor (tan delta), partial discharges, voltage endurance test (VET) and breakdown. Among the results of the physicochemical properties it was possible to verify an initial increase of three times the value of viscosity for RN resin compared to RE. However there was no detriment of the dielectric characteristics depending on the viscosity, what was proven with the results of dissipation factor and VET. It was obtained a value of Tg of 116°C and 145°C for RN and RE respectively, what could limit its employment for hydrogenerators as being below the operational temperature. Among the results of electrical tests for the resins it was observed that: (i) the dissipation factor and VET are practically the same for both resins; (ii) the tip-up value resulted in 0,014% for RE and 0,020% for RN, being required lower than 0,25% according to the norm EN 50209 and (iii) the estimating lifecycle was approximately 40 years for both types of resin, what is applicable for most windings under operation. In this context it is suggested that the RN resin can be a good alternative for RE resin with an equivalent performance once the process conditions and employment temperature are adjusted
Mestrado
Ciencia e Tecnologia de Materiais
Mestre em Engenharia Química
41
Hirschberger, Maximilian Anton. "Quasiparticle Excitations with Berry Curvature in Insulating Magnets and Weyl Semimetals." Thesis, Princeton University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10286472.
Full textAbstract:
The concept of the geometric Berry phase of the quantum mechanical wave function has led to a better theoretical understanding of natural phenomena in all fields of fundamental physics research. In condensed matter physics, the impact of this theoretical discovery has been particularly profound: The quantum Hall effect, the anomalous Hall effect, the quantum spin Hall effect, magnetic skyrmions, topological insulators, and topological semimetals are but a few subfields that have witnessed rapid developments over the three decades since Michael Berry's landmark paper. In this thesis, I will present and discuss the results of three experiments where Berry's phase leads to qualitatively new transport behavior of electrons or magnetic spin excitations in solids.
We introduce the theoretical framework that leads to the prediction of a thermal Hall effect of magnons in Cu(1,3-bdc), a simple two-dimensional layered ferromagnet on a Kagomé net of spin S = 1/2 copper atoms. Combining our experimental results measured down to very low temperatures T = 0.3 K with published data from inelastic neutron scattering, we report a quantitative comparison with the theory. This confirms the expected net Berry curvature of the magnon band dispersion in this material.
Secondly, we have studied the thermal Hall effect in the frustrated pyrochlore magnet Tb2Ti2O7, where the thermal Hall effect is large in the absence of long-range magnetic order. We establish the magnetic nature of the thermal Hall effect in Tb2Ti2O7, introducing this material as the first example of a paramagnet with non-trivial low-lying spin excitations. Comparing our results to other materials with zero thermal Hall effect such as the classical spin ice Dy2Ti 2O7 and the non-magnetic analogue Y2Ti2O 7, we carefully discuss the experimental limitations of our setup and rule out spurious background signals.
The third and final chapter of this thesis is dedicated to electrical transport and thermopower experiments on the half-Heusler material GdPtBi. A careful doping study of the negative longitudinal magnetoresistance (LMR) establishes GdPtBi as a new material platform to study the physical properties of a simple Weyl metal with only two Weyl points (for magnetic field along the crystallographic ⟨111⟩ direction). The negative LMR is associated with the theory of the chiral anomaly in solids, and a direct consequence of the nonzero Berry curvature of the energy band structure of a Weyl semimetal. We compare our results to detailed calculations of the electronic band structure. Moving beyond the negative LMR, we report for the first time the effect of the chiral anomaly on the longitudinal thermopower in a Weyl semimetal.
42
Li, Ruihua. "Devitrification behaviour of alkaline-earth silicate fibre." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/19960/.
Full textAbstract:
The alkaline-earth silicate fibres are a new generation of man-made insulation materials. The materials are amorphous on manufacture and have been shown to be soluble in physiological solutions and to be cleared from the lung in animal exposure trials. This reported study provides a thorough investigations of the devitrification behaviour of Superwool X-607 (Morgan Materials Technology), and two further compositions, code names A2 and B3.Thermal exposures were made within the region extending from 700 to 1250°C and 10 minutes to 3240 hours in clean furnace environments. The devitrified microstructures and products were identified using X-ray powder diffraction and analytical electron microscopy. Details are provided of the development of specimen preparation techniques to enable fibre cross-sections to be analyzed in the TEM.The devitrification products are presented as a function of exposure temperature and time for all 3 compositions. The amorphous glass separated into a silica-rich phase and an alkaline-earth silicate rich phase and the development of these amorphous phases is presented and discussed. The subsequent devitrification of these separated phases into associated silica crystalline phases and alkaline-earth silicate crystalline phases, and, in each case, the subsequent phases and transformations with increasing thermal exposure are also presented and discussed. For the crystalline silica phases, the following unusual transformation situation was identified in all 3 compositions: amorphous silica → alpha-quartz → alpha-cristobalite → tridymite. In comparison with established understanding of silica phase transformations, the following anomalies were identified and explained: a) the formation of quartz as the primary crystalline silica phase at temperatures ≥1000°C, and b) the subsequent formation of alpha-cristobalite, the low-temperature form, other than B-cristobalite, the high-temperature form, which was the only silica phase identified in the devitrified aluminosilicate fibres. For the alkaline-earth silicate phases, two forms of wollastonite solid solution were characterised. The low-temperature form, containing more Mg[2+], transforms to the high-temperature form and diopside at temperatures above 900°C. The low-temperature anomaly, ie the formation of the immature high-temperature form below 900°C is possibly due to a secondary phase separation. Pseudowollastonite was found to be metastable in the investigated temperature region. It is suggested that the detailed transformation process among these alkaline-earth silicate phases has been identified for the first time. This thesis also includes a detailed review of published studies concerning this materials systems as well as recommendations for further work.
43
Schlanbusch, Reidun Dahl. "A New Nano Insulation Material for Applications in Zero Emission Buildings." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20682.
Full textAbstract:
New materials with extremely low thermal conductivities are interesting because they can have architectonic, technical and possibly economic benefits in buildings. A new nano insulation material (NIM) is under development at the Research Centre on Zero Emission Buildings (ZEB). Both the environmental impact of the material and its thermal conductivity are crucial design perspectives for the new material. The objective in this report was to investigate the mechanisms behind these two parameters, and how they can be optimized. The first part of the report addressed the insulation performance. In order to lower the thermal conductivity through, inter alia, the Knudsen effect, the NIM is based on the idea of creating a porous material with extremely small pores. Hollow silica nanospheres (HSN) are produced bottom-up through a template-assisted sol-gel synthesis. To date, there have been no concrete suggestions on how to assemble the spheres to form a porous insulation material – the NIM. The effective thermal conductivity of the NIM, which is already known to be dependent on multiple parameters and advanced physical effects, was found to be dependent also on macroscopic effects in the assembled insulation unit. The second part of the report addressed the environmental performance of the NIM. Life cycle assessment was used to calculate green house gas emissions and energy consumption for the production scenarios close to the current synthesis procedure of the NIM. The life cycle assessment model was constructed with flexibility and can be used for further research. The results are in the order of 60 kg CO2 equivalents and 1400 MJ cumulated energy demand per kg of material, for the scenario where ethanol consumption is reduced by 50% relative to the laboratory consumption. The indirect energy and emission intensity of the raw materials consumed in the NIM production were found to be the main drivers for the environmental impact of the NIM. Especially the chemicals in the sol-gel synthesis. The two parts of the report are connected: Higher environmental costs can be tolerated per unit material thickness, if the thickness can be kept small. The results from the LCA indicate that the environmental impact of the NIM risks being relatively high, even if very low thermal conductivities can be obtained. Hence strict optimization of both insulating and environmental performance is necessary. It was concluded that the most important recommendations for this optimization include avoiding introducing phases with higher thermal conductivities than the HSN in the assembly step and reviewing the consumption of chemicals the silica synthesis procedure.
44
Twumasi, Afriyie Ebenezer. "Preparation and Evaluation of New Nanoporous Silica Materials for Molecular Filtration and for Core Materials in Vacuum Insulation Panels." Doctoral thesis, KTH, Byggnadsteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-120330.
Full textAbstract:
Nanoporous materials for gas purification and thermal insulation have been studied and developed for application in many areas. It is known that a single adsorbent may not adequately control multiple contaminants. Further the utilization of nanoporous material as thermal insulator in building applications is limited due to high cost. Moreover, in view of the global environmental movement for clean air and reduction of heating energy consumption in built environment, the development of new and better nanoporous materials will not only facilitate major advances in gas adsorption and thermal insulation technology, but also meet the new challenges that cannot be met with the nanoporous materials that are currently available. This thesis presents a synthesis of new nanoporous silica based materials, and the characterization and application of these materials for molecular filtration and thermal insulation. Commercial nanoporous materials have been used for benchmarking for the pore properties, the applicability, and the performance of these new materials. First a double metal-silica adsorbent has been synthesized. The preparation procedure is based on the use of sodium silicate coagulated with various ratios of magnesium and calcium salts which yields micro-meso porous structures in the resulting material. The results show that molar ratios of Mg/Ca influence the pore parameters as well as the structure and morphology. The bimodal pore size can be tailored by controlling the Mg/Ca ratio. In the second synthesis, pure mesoporous silica, SNP has been prepared using glycerol as pore forming agent and monovalent salts as coagulant. This leads to material with large surface area and uniformed pore size centred at 43 or 47 nm. The materials further exhibits a low bulk density in the range of 0.077 to 0.122 g/ml and possess a high porosity in the range of 95-97%. The influence of acid type (organic or inorganic) on the pore parameters and on the tapped density has also been investigated. A synthesis method has also been developed for the preparation of carbon-silica composites. The method involves a number of routes, which can be summarised as addition of activated carbon particles to (I) the paste, (II) the salt solution, or (III) with the sodium silicate solution. In route II and III the activated carbon is present before coagulation. The routes presented here leads to carbon-silica composites possessing high micro porosity, meso porosity as well as large surface areas. The results further shows that pore size distribution may be tailored based on the route of addition of the carbon particles. Following route I and III a wide pore size (1-30 nm) was obtained whereas by route II a narrow pore size (1-4 nm) was observed. MgCa-silica chemisorbents were also developed using either potassium hydroxide or potassium permanganate as impregnate chemicals. A direct or post-impregnation procedure was employed. The results revealed that the impregnate route and amount cause a reduction in both specific surface area and pore volume. Finally the thermal conductivity and dynamic adsorption of H2S, SO2 andtoluene were measured. Results show that at room temperature and atmospheric pressure, a thermal conductivity of 28.4 and 29.6 mW/m.K were obtained for the SNP mesoporous silicas. The dynamic adsorption behaviour of the chemisorbents and composites indicate their ability to absorbed H2S, SO2 andtoluene respectively. The highest H2S uptake corresponds to chemisorbents with 11.2-13.6 wt% KMnO4. The effect of impregnation route, amount of KMnO4 and its location in the pore system are likely the key factors in achieving a large H2S uptake. For SO2 adsorption, the highest uptake capacity was observed for MgCa-68/32-KOH. The results further suggest that the key to large SO2 uptake is as a result of the synergetic effect between large mesopore diameter and extensive mesopore volumes. Carbon-silica composites with carbon content 45 wt % exhibits high toluene adsorption with composite via route I having the highest toluene adsorption capacity (27.6 wt % relative to carbon content). The large uptake capacity of this composite was attributed to the presence of high microporosity volume and a wide (1-30 nm) bimodal pore system consisting of extensive mesopore channels (2-30 nm) as well as large surface area. These capacity values of carbon-silica composites are competitive to results obtained for commercial coconut based carbon (31 wt %), and better than commercial alumina-carbon composite (9.5 wt %).QC 20130408
45
Bandaru, Venkata Raghava Sunil Kumar Reddy. "Deformation and Durability Studies of Insulation Polymers." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1227191899.
Full text
46
Mu, Rui Lin. "Improvement of Sound Insulation Performance of Multi-layer Structures in Buildings." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174914.
Full text
47
Sierra, Pérez Jorge. "The introduction of eco-design for promoting the use of eco-materials: the cork as building material." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/400141.
Full textAbstract:
El corcho es un material natural, renovable y concentrado en el área Mediterránea, principalmente en la Península Ibérica, donde también se concentra la actividad de extracción del material. El corcho se extrae de una forma sostenible de la corteza del alcornoque sin dañar al árbol ni afectando su biodiversidad. La principal aplicación del corcho es como tapón para botellas de vino y cava. Este trabajo ha tomado el testigo de un estudio anterior sobre el sector catalán del corcho llevado a cabo para analizar los diferentes sistemas y subsistemas del sector desde una perspectiva ambiental. Este estudio destacó la necesidad de investigar en la diversificación de los productos de corcho, dando un mayor valor añadido al recurso, evitando la concentración excesiva del mercado del corcho en los productos del mercado vitivinícola. Este ha sido el principal objetivo de este trabajo, promoviendo su uso en el sector de la. Esta tesis se apoya en diferentes estudios específicos relacionados con la caracterización económica del sector ibérico del corcho, la evaluación ambiental de los actuales sistemas de aislamiento en edificios y mediante la introducción de los métodos de ecodiseño con el objetivo de la diversificación del mercado del corcho.
La caracterización del sector ibérico del corcho identificó importantes diferencias entre los sectores de Portugal, España y Cataluña. Los primeros son principalmente productores y procesadores de materia prima, siendo líderes mundiales, y en el caso de Portugal con una potente industria. Mientras tanto, el sector español está centrado en la materia prima y productos básicos de corcho con un bajo o intermedio valor. Por otra parte, el sector de la construcción fue identificado como un mercado potencial en el que promover el corcho como material a través del ecodiseño de nuevos productos.
El Análisis del Ciclo de Vida (ACV) es un método de ecodiseño utilizado para la evaluación de los impactos ambientales de productos y servicios a lo largo de su ciclo de vida. Este método fue utilizado para evaluar los actuales productos aislantes de corcho para la construcción, así como para analizar ambientalmente los materiales aislantes y las soluciones constructivas más utilizados. Los resultados concluyeron que las actuales soluciones aislantes de corcho no se ajustan a los requisitos para competir con los materiales aislantes comunes, porque generan mayores impactos ambientales. Por lo tanto, el uso del corcho como material natural y renovable no necesariamente implica un mejor desempeño ambiental de los edificios. Sin embargo, si se mejorasen los procesos de fabricación de estos productos a través de la ecoinnovación, se podrían conseguir productos más eficientes, mejorando su competitividad en el mercado. Además, la integración de la metodología ACV con simulaciones térmicas dinámicas es presentada en este trabajo evaluando la rehabilitación de un edificio existente para el ahorro energético. Esta integración se consideró útil para la caracterización energética de edificios y permite obtener resultados más realistas.
Finalmente se llevó a cabo un proceso de ecoideación para generar nuevos conceptos de producto. La versatilidad del corcho encajó perfectamente con los métodos creativos utilizados, debido a la singular combinación de sus propiedades. Algunas de ellas, como su capacidad portante, su permeabilidad al vapor de agua y su ligereza, originaron los conceptos más interesantes, enfocados en la minimización del uso de materiales en los sistemas de aislamiento térmico o en el tratamiento de humedades. Además se destacó la singular estética del corcho para dotar al edificio de un aspecto único. Este trabajo ha llegado a la conclusión de la gran conveniencia y posibilidades del corcho para uso en los edificios, y además de la idoneidad del concepto del ciclo de vida en la metodología interdisciplinar propuesta.Cork is a natural, renewable material, typically concentrated in Mediterranean areas. The cork oak forests are mainly located in the Iberian Peninsula, and, therefore, where the most cork extraction activity is located. Cork is sustainability extracted from cork oak outer bark without damaging the tree or affecting biodiversity. The main current application of cork is as closure for wine and champagne bottles. The present dissertation has taken up the baton of a previous study about the Catalan cork sector carried out to analyse different system and subsystems of the sector from an environmental approach. That study highlighted the need of investigation in new field: diversification of cork products, giving more added value to the resource, and avoiding the excessive concentration of cork sector applications in wine markets. The main objective of this dissertation was to address the diversification of cork sector, promoting its use in the building sector through the use of an interdisciplinary methodology framework from an environmental approach. This thesis was supported by several specific studies related to the economic characterization of the Iberian cork sector, the environmental assessment of current system for building insulation and the introduction of eco-design methods for the diversification of cork market. The characterization of the Iberian cork sector identified important differences between Portuguese, Spanish and Catalan sectors. The formers are producers and processors of raw cork, acting as leader in the global market, and in the case of Portugal acting as a very powerful industry. Meanwhile, Spain sector is focussed on raw material and low intermediate basic cork products. Moreover, the building sector was identified as potential market on which promote cork material through the eco-design of new products. Life Cycle Analysis (LCA) is an eco-design method used to assess the environmental impacts of products and systems throughout their life. This method was used to assess the current cork insulation product for buildings, and also the most common insulation materials and constructive solution on which could be installed. Results concluded that currently cork solutions did not fit the requirements to compete with the most common insulation materials, because caused more environmental impacts. So, the use of cork as a natural and renewable insulation material did not necessarily imply a better environmental performance in buildings. However, if manufacturing processes improve thanks to processes eco-innovation, this solution should be more efficient and can reach a better competitiveness of the product in the market. Moreover, the integration of LCA methodology with Thermal Dynamic simulation was also presented in this dissertation, to evaluate the energy saving renovation of an existing building. This integration was identified as suitable in the energy characterization of buildings and allowed obtaining more realistic results. Once the initial situation was analysed, an eco-ideation process was carried out to generate new concepts of products, and the versatility of cork fitted perfectly with the creative methods used, due to the singular combination of cork properties. Some specific physical characteristics of cork, self-supporting, water vapour permeability and lightness, originated the most interesting concepts focused on the minimisation of materials use in the internal insulation systems or the treatment of moisture, in addition giving to the building a unique aspect due to the singular aesthetic of cork. This dissertation has concluded the great convenience and possibilities of cork for its use in buildings, and the suitability of the life cycle thinking in the proposed interdisciplinary methodology.
48
Sitorus, Henry Binsar Hamonangan. "The study of jatropha curcas oil-based biodegradable insulation materials for power transformer." Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0022/document.
Full textAbstract:
Ce travail porte sur la caractérisation physico-chimique de l'huile de Jatropha Curcas et sa capacité à remplacer l'huile minérale dans les transformateurs de puissance. Ce produit présente plusieurs avantages sur les autres huiles végétales comme l'huile de palme ou l'huile de colza, qui recommandent sa production et son utilisation. En effet, la plante de Jatropha Curcas peut être cultivée sur des sols pauvres à faibles précipitations, évitant ainsi d'utiliser des sols plus fertiles pour sa culture permettant ainsi aux petits exploitants de réserver leurs terres aux cultures de base. Cette plante peut pousser facilement dans des zones où les niveaux de précipitations annuelles sont nettement inférieures à celles requises par d'autres espèces telles que le colza, le tournesol, le soja, le maïs, le palmier à huile et d'autres. Elle peut être cultivée sur tous les types de sol en Indonésie, même sur des terres arides, dans de nombreuses régions de l'Indonésie orientale, inexploitées en raison des difficultés à planter d'autres cultures. En outre, l'huile de Jatropha Curcas est un produit non alimentaire. En faisant subir à l’huile de Jatropha Curcas brute une estérification à base alcaline avec de l'hydroxyde de potassium (KOH), on obtient de l’huile de méthylester de Jatropha Curcas (JMEO) dont la viscosité et l’acidité sont acceptables pour les équipements à haute tension en particulier pour les transformateurs de puissance. Les propriétés physico-chimiques et électriques de JMEO ont été mesurées ainsi que celles de l'huile minérale (MO) pour la comparaison. Pour les propriétés physico-chimiques, il s’agit de la densité relative, la teneur en eau, la viscosité, l'acidité, l'indice d'iode, la corrosivité, le point d'éclair, le point d'écoulement, la couleur, l'examen visuel, et la teneur en ester méthylique. Quant aux propriétés électriques, elles concernent la rigidité diélectrique sous différentes formes de tension (alternative, continu et choc de foudre), les phénomènes de pré-claquage et de claquage sous choc de foudre, les décharges glissantes sur les surfaces de carton comprimé, immergé dans JMEO et MO. Les résultats obtenus montrent que les tensions de claquage moyennes en continu et en choc de foudre des huiles JMEO et MO sont très proches ; la tension de claquage moyenne de JMEO est même plus élevée que celle de l'huile minérale (de type naphténique). La mesure des tensions de claquage des mélanges d'huiles «80% JMEO + 20% MO» et «50% JMEO et 50% MO» montrent que la tension de claquage du mélange «80% JMEO + 20% MO» est toujours supérieure à celle de l'huile minérale sous tensions alternative et continue. Cela indique que le mélange d'huile minérale et de JMEO avec un rapport de 20:80 ne dégrade pas ses performances. Le mélange d'huiles peut se produire lors du remplacement de l'huile minérale par JMEO dans les transformateurs installés et en exploitation. L'analyse des caractéristiques des streamers (la forme, le temps d'arrêt, le courant associé et la charge électrique) se développant dans les huiles JMEO et MO sous tension impulsionnelle de foudre, montre une grande similitude. Aussi, la longueur finale (Lf) et la densité des branches des décharges surfaciques se propageant sur le carton comprimé immergé dans l'huile de Jatropha Curcas de méthylester (JMEO) et de l'huile minérale (MO), sous tensions de choc de foudre positif et négatif (1,2/50 μs), pour deux configurations d'électrodes divergentes (électrode pointe haute tension perpendiculaire et tangente au carton, respectivement), sont fortement influencées par l'épaisseur du carton comprimé. Pour une épaisseur donnée, Lf augmente avec la tension et décroît lorsque l'épaisseur augmente. Lf est plus long lorsque la pointe est positive que lorsque la pointe est négative. Pour une tension et une épaisseur du carton comprimé donnée, les valeurs de Lf dans l’huile minérale et l’huile JMEO sont très proches. [...]This work is aimed at the investigation of the physicochemical characterization of Jatropha Curcas seeds oil and its capacity to be an alternative option to replace mineral oil in power transformers. This product presents several advantages that recommend both its production and usage over those of other vegetable oils as crude palm oil and rapeseeds oil. Indeed, it may be grown on marginal or degraded soils avoiding thus the need to utilize those more fertile soils currently being used by smallholders to grow their staple crops; and it will readily grow in areas where annual rainfall levels are significantly lower than those required by other species such as palm oil, rape-seeds oil, sunflower oil, soybeans oil, corn oil and others. For instance, these plants can grow on all soil types in Indonesia, even on barren soil. The barren soil types can be found in many parts of eastern Indonesia that remain untapped because of the difficulty planted with other crops. Moreover, jatropha curcas oil is nonfood crops. Jatropha Curcas oil was processed by alkali base catalyzed esterification process using potassium hydroxide (KOH) to produce Jatropha Curcas methyl ester oil (JMEO) has a viscosity and a acidity that are acceptable for high voltage equipment especially in power transformer. The physicochemical and electrical properties of JMEO were measured as well as those of mineral oil (MO) for comparison. The physicochemical properties cover relative density, water content, viscosity, acidity, iodine number, corrosivity, flash point, pour point, color, visual examination, and methyl ester content. Meanwhile the electrical properties cover dielectric strength under AC, DC and lightning impulse voltages, pre-breakdown / streamers under lightning impulse voltage, creeping discharge over pressboard immersed in JMEO and MO. The obtained results show that the average DC and lightning impulse breakdown voltages of JMEO and MO are too close, even the average AC breakdown voltage of JMEO are higher than that of mineral oil (napthenic type). The measurement of breakdown voltages of two oil mixtures namely “80% JMEO + 20% MO” and “50% JMEO and 50% MO” shows that the breakdown voltage of the first mixture (i.e., “80%JMEO+20%MO”) is always higher than that of mineral oil under both AC and DC voltages. This indicates that mixing 20:80 mineral oil to JMEO ratio does not degrade its performance. The mixing of oils can occur when replacing mineral oil by JMEO in installed transformers. The analysis of the streamers characteristics (namely; shape, stopping length, associated current and electrical charge) developing in JMEO and MO under lightning impulse voltages, shows that these are too close (similar). It is also shown that the stopping (final) length Lf and the density of branches of creeping discharges propagating over pressboard immersed in Jatropha Curcas methyl ester oil (JMEO) and mineral oil (MO), under positive and negative lightning impulse voltages (1.2/50 μs), using two divergent electrode configurations (electrode point perpendicular and tangential to pressboard), are significantly influenced by the thickness of pressboard. For a given thickness, Lf increases with the voltage and decreases when the thickness increases. Lf is longer when the point is positive than with a negative point. For a given voltage and thickness of pressboard, the values of Lf in mineral oil and JMEO are very close. It appears from this work that JMEO could constitute a potential substitute for mineral oil for electrical insulation and especially in high voltage power transformers
49
Elsayad, Kareem. "Understanding the insulating phases of disordered materials through crosstalk and Coulomb drag experiments." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3290773.
Full textAbstract:
Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2007.Title from dissertation home page (viewed May 28, 2008). Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7391. Adviser: John P. Carini.
50
Ariffin, Azrul Mohd. "The measurement and modelling of electroluminescence in high voltage polymeric cable insulation materials." Thesis, University of Southampton, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494683.
Full textAbstract:
Since space charge plays a significant role in long-term electrical degradation of polymeric insulation in high voltage cables, there is growing interest in the measurement of the energy dissipation of mobile and trapped charges in the dielectric molecules. The dissipation process is associated with the emission of visible photons, a process known as electroluminescence (EL) and can be used, potentially, as an indicator for the inhibition of electrical ageing of insulation. This thesis is based on an investigation into the occurrence of EL in dielectric materials as a result of applying high ac stresses. The phenomenon has been observed and analyzed for different types of thin polymeric films using a charge coupled device (CCD) detection system. This unique experimental setup enables a range of measurements to be performed including the imaging of EL, its temporal behaviour, spectral analysis and phase-resolved measurements using the same detector. The effects of several factors such as the types of material under study and local gas environment have been assessed based on the results obtained. Previously, different research groups have monitored the occurrence of EL under ac conditions by applying a sinusoidal electric field across the polymer but in this project, the emission is also examined under the influence of triangular and square voltage waveforms, together with their asymmetrical counterparts. In addition to this, a dynamic bipolar charge recombination model has been developed in order to simulate studies of EL under an alternating field. By comparing experimental results with the stimulation, the theories relating to the processes responsible for the occurrence of EL have been evaluated and a good agreement was found between the simulation and experimental results.