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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Thermoplastic elastomers based on polyester recycled tire fibers and ground tire rubber

Moghaddamzadeh, Siavosh 05 July 2018 (has links)
Ce projet porte sur la production et la caractérisation de composites hybrides basés sur un polymère thermoplastique (polyéthylène linéaire de basse densité, LLDPE) avec des fibres de polyester de pneus recyclés (RTF) mélangées avec le caoutchouc des pneus usés (GTR) avec et sans styrène-éthylène-butylène-styrène greffé d’anhydride maléique (SEBS-g-MA) comme compatibilisant. L'étude vise à améliorer les propriétés du LLDPE avec le RTF, GTR et SEBS-g-MA. La première étape de l'étude est composée de deux parties principales. La première partie porte sur la caractérisation des RTF par spectroscopie infrarouge à transformée de Fourier (FTIR), spectroscopie des photoélectrons X (XPS), analyse thermogravimétrique (TGA), calorimétrie différentielle à balayage (DSC), microscopie électronique (SEM) et densité; tandis que la deuxième partie rapporte la morphologie des composites fabriqués à partir de différentes conditions. En particulier, l'effet de la concentration de RTF (10, 25 et 50% en poids) avec et sans 10% poids de SEBS-g-MA à différentes vitesses de vis (110, 180 et 250 rpm) en-dessous (LT) et au-dessus (HT) de la température de fusion du RTF (253°C) est étudié par extrusion double-vis suivie du moulage par injection. Les résultats montrent une meilleure distribution des particules GTR (intégrées au RTF) dans la matrice (LLDPE) avec l'augmentation du contenu en RTF dans les mélanges compatibilisés. En outre, l’augmentation de la vitesse des vis entraîne une réduction de la longueur des RTF et de la taille des GTR. Cependant, un profil HT mène à la dégradation de la matrice et du GTR. Dans la deuxième étape du travail, une série complète de caractérisation physique (densité et dureté) et mécanique (tension, flexion et impact) des échantillons produits dans la première partie est présentée. Malgré la diminution des modules et des contraintes maximales, la résistance au choc Charpy augmente de 50% avec 50% de FTR compatibilisées et une amélioration supplémentaire de 56% à haute vitesse de rotation des vis (250 rpm). Cependant, le profil HT diminue toutes les propriétés physico-mécaniques des mélanges. Finalement, les propriétés rhéologiques des échantillons produits lors de la première partie ont été rhéologiquement caractérisés à l’état fondu (cisaillement oscillatoire de faible amplitude, SAOS) et solide (analyse mécanique dynamique, DMA) afin de déterminer les relations entre la mise en œuvre, la morphologie et les propriétés macroscopiques. Les résultats montrent une augmentation de l'élasticité des mélanges avec l’augmentation du contenu en RTF en présence de SEBS-g-MA surtout à des vitesses de vis élevées. Néanmoins, le profil HT présente une diminution de l'élasticité à l’état fondu, tandis que la DMA montre une augmentation de l’élasticité pour le profil LT. / This project focuses on the production and characterization of hybrid composites based on a thermoplastic polymer (linear low-density polyethylene, LLDPE) and polyester recycled tire fibers (RTF) mixed with ground tire rubber (GTR) with and without styrene-ethylenebutylene-styrene grafted maleic anhydride (SEBS-g-MA) as a compatibilizer. The study aims at improving the properties of LLDPE using RTF, GTR and SEBS-g-MA. The first step is composed of two main parts. The first part is the characterization of RTF via Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and density; while the second part is to report on the morphology from different processing parameters. In particular, the effect of RTF concentration (10, 25 and 50 wt.%) with and without 10 wt.% SEBS-g-MA at different screw speeds (110, 180 and 250 rpm) processed below (LT) and above (HT) the RTF melting temperature (253°C) are investigated for samples produced via twin-screw extrusion followed by injection molding. The results show better GTR particles distribution (imbedded in RTF) in the matrix (LLDPE) with increasing RTF content in the compatibilized compounds. Also, increasing the screw speed leads to a reduction of RTF length and GTR sizes. However, HT profiles produced degradation of the matrix and GTR particles. In the second step, a complete series of physical (density and hardness) and mechanical (tension, flexion and impact) characterization was performed on the samples produced in the first step. Despite lower moduli and strength, Charpy impact strength increases by 50% for compatibilized 50% RTF compounds with an additional 56% improvement at higher screw speed (250 rpm). However, HT profiles decrease all physico-mechanical properties of the samples. Finally, the rheological properties of the samples produced in the first step are investigated in both the melt (small amplitude oscillatory shear, SAOS) and solid (dynamic mechanical analysis, DMA) states to understand the relations between processing, morphology and macroscopic properties. The results show increased elasticity with increasing RTF content with SEBS-g-MA, especially at higher extrusion screw speeds. HT profiles lead to lower elasticity in the melt state, while DMA results show higher elasticity for LT profiles.
192

Development of Controlled Ring-Opening Polymerization of  O-Carboxyanhydrides

Zhong, Yongliang 27 October 2020 (has links)
The aim of my Ph.D. thesis is to summarize my research on the development of ring-opening polymerization (ROP) of O-carboxyanhydrides (OCAs) to synthesize functionalized, degradable polyesters. Biodegradable polyesters are promising alternatives to conventional petroleum-based non-degradable polyolefins and they are widely used in everyday applications ranging from clothing and packaging to agriculture and biomedicine. Commercially available polyesters, such as poly(lactic-co-glycolic acid), poly(lactic acid), and polycaprolactone, hydrolyze in physicochemical media. They have been approved by FDA and widely used for medical applications. However, the lack of side-chain functionality in polyesters and in corresponding monomers greatly plagues their utility for applications that demand physicochemical properties such as high stiffness, tensile strength and elasticity. Increasing efforts have been devoted to the introduction of pendant groups along the polymer chain in order to modify and modulate the physicochemical properties of polyesters and thereby to expand their applications. Over the last decade, OCAs have emerged as an alternative class of highly active monomers for polyester polymerization. OCAs are prepared from amino acids and thus have a richer range of side chain functionalities than lactone or lactide. Like lactones, OCAs can undergo ROP to obtain polyesters. Unfortunately, current ROP methods, especially those involving organocatalysts, result in uncontrolled polymerization including epimerization for OCAs bearing electron-withdrawing groups, unpredictable molecular weights (MWs), or slow polymerization kinetics. Based on our recent success of Ni/Ir photoredox catalysis allowing for rapid synthesis of high-MWs polyesters, we further explore new polymerization chemistry to use earth-abundant metal complexes to replace expensive rare-earth metal photocatalysts, and practice the polymerization in moderate and energy-efficient reaction conditions. This thesis introduces novel photoredox and electrochemical earth-abundant metal catalysts that overcome above difficulties in the ROP chemistry of OCAs, and allow for the preparation of stereoregular polyesters bearing abundant side-chain functionalities in a highly controlled manner. Specifically, various highly active metal complexes have been developed for stereoselective ROP of OCAs, either using light or electricity, to synthesize syndiotactic or stereoblock copolymers with different thermal properties. Additionally, simple purification protocols of OCAs have also been initially studied, which potentially paves the way to bulk production of functional monomers. In this thesis, I first describe newly-developed photoredox Co/Zn catalysts to achieve a controlled ROP of enantiopure OCAs under mild reaction conditions (Chapter 2). Such discovery is extended to the combination use of Co catalysts with various Zn/Hf complexes that enable stereoselective controlled ROP of racemic OCAs for the preparation of stereoregular polyesters (Chapter 3). The mechanistic studies of the aforementioned developments lead to the application of such a catalytic system in controlled electrochemical ROP of OCAs (Chapter 4). Such chemistry can also be translated to stereoselectively electrochemical ROP of racemic OCAs to either syndiotactic or stereoblock polyesters, allowing precise control of polyester's tacticity and sequence (Chapter 5). An overview future work has been summarized (Chapter 6). / Doctor of Philosophy / Polyesters are widely used in everyday applications ranging from clothing and packaging to agriculture and biomedicine. Different from conventional unrecyclable plastics, polyesters are usually biocompatible and biodegradable, and can be synthesized from renewable resources. A few commercially available polyesters have been approved by FDA and widely used for medical applications. However, their utility for applications that demand various mechanical and chemical properties is greatly limited by the lack of side-chain functional groups in polyesters and in their monomers—lactones. Increasing efforts have been devoted to the introduction of pendant groups along the polymer chain in order to modify and modulate the desired properties of polyesters and thereby to expand their applications. Over the last decade, O-carboxyanhydrides (OCAs) have emerged as an alternative class of highly active monomers for polyester polymerization. OCAs can be prepared from renewable source amino acids and thus have a richer range of side chain functional groups. Like lactones, OCAs can undergo ring-opening polymerization (ROP). Unfortunately, current ROP methods usually result in uncontrolled polymerization of OCAs including loss of stereoregularity, unpredictable molecular weights, or slow polymerization rate. To address the above-described polymer chemistry and materials challenges, I have been motivated to develop a new polymer chemistry knowledge base when starting my Ph.D. program. I was first involved in the development of a controlled photoredox polymerization of OCAs produces polyesters with various side chain functional groups. By using photoredox Ni/Zn/Ir catalysts, stereoregular high molecular weight polyesters can be synthesized from racemic OCAs in a rapid, controlled manner. However, this catalytic system has to be used at -20 °C despite so successful in preparing stereoblock polyesters. Encouraged by our recent success in this area, I started to work on the discovery of other transition metal complexes such as the Co complexes used in N-carboxyanhydride polymerization. Ultimately, innovative photoredox Co/Zn catalysts has been successfully developed, and applied to our protocol to achieve the controlled ROP of enantiopure OCAs under mild reaction condition (Chapter 2). The Co catalyst can replace both Ni and Ir in aforementioned photoredox system. Meanwhile, the combination of Co catalysts and various Zn/Hf complexes has also been developed to undergo photoredox ROP of racemic OCAs to efficiently produce polyesters with different microstructures (Chapter 3). Although photoredox ROP is an efficient method for synthesizing degradable polyesters, great decrease in photonic flux with the depth of the reaction medium makes it less energy efficient compared to electricity. Therefore, we then extended our protocol to electrochemical reaction, which is one of the most energy-efficient chemical reactions. The newly identified Co/Zn catalytic system can be activated by electric current to mediate rapid electrochemical ROP (eROP) of enantiopure OCAs, allowing for the synthesis of isotactic polyesters in a highly controlled manner (Chapter 4). Additionally, stereoselective eROP of racemic OCAs has been firstly achieved by using various combinations of Co and Zn/Hf complexes (Chapter 5). In summary, my research produces unique and transformative insights into the innovative photoredox and electrochemical ROP mediated by metal catalysts. Given the importance and versatility of biodegradable and biocompatible polyester materials, the chemistry invented by our team can be expected to serve as a new platform for various applications in material and biomedical engineering.
193

Establishment of a Resource-efficient Spray Dyeing Process for Polyester Fabrics : A study on the key process steps of the hydraulic spray atomising system—pre-treatment, dyeing, predrying, and fixation

Mae Amandoron, Kristine January 2024 (has links)
The production of polyethylene terephthalate (PET) textiles, commonly known as polyester, is an energy and water-intensive process, particularly during the dyeing and finishing stages, leading to significant carbon emissions and wastewater filled with toxic chemicals. Conventional dyeing processes consume large volumes of water and energy, making them environmentally harmful. Innovative methods like hydraulic spray atomizer offer a more sustainable alternative by reducing water and chemical usage, thus minimizing waste and environmental impact. This study explores the hydraulic spray dyeing process parameters, including pre-treatment, dyeing, pre-drying, and fixation steps for three different polyester fabrics. The objective is to achieve resource-efficient dyeing with comparable results to traditional methods, and to compare effectiveness of a combined pre-treatment and dyeing approach with a two-step spray application of pre-treatment and dyeing. Pre-treatment of the polyester fabrics with chemical hydrophilizing agents by spray application showed to improve the hydrophilic character and wetting capacity of three polyester fabrics—P75, P600, and Kibo based on reduced water contact angle measurements and increased vertical wicking rates. A pre-treatment also showed to enhance the K/S values of the three different polyester fabrics. The addition of a pre-drying step showed some indication of reducing disperse dye migration, and enhanced color strength of the Kibo fabrics. Spray dyed samples maintained dyeing quality comparable to padded samples. One-step spray processes demonstrated comparable or improved color properties and durability to fastness to washing and abrasion in comparison to two-step processes. The results demonstrate that the hydraulic spray atomizing system is viable for both dyeing and pre-treatment of polyester fabrics. Furthermore, this lays the groundwork for innovation in wet textile processes of polyester fabrics using this resource-efficient alternative, aiming towards sustainable textile production and dyeing.
194

Effet de la cristallinité sur la perméabilité aux gaz de films à base d'acide polylactique

Ghassemi, Amir 24 April 2018 (has links)
Le but principal de ce travail est de déterminer l’effet de la cristallinité sur la perméation aux gaz pour des films polymères. En particulier, on utilise l’acide polylactique (PLA) comme matrice et différents gaz (azote, dioxyde de carbone, hydrogène, méthane et oxygène) pour les propriétés de transfert. À cet effet, le travail a été divisé en trois parties. Dans la première partie, on utilise le talc comme agent de nucléation afin de modifier la cristallinité du PLA. Dans ce cas, on remarque que la perméabilité au gaz et le coefficient de diffusion sont réduits en augmentant la teneur en talc (0-3% poids). On constate aussi que l’augmentation de la cristallinité due à la nucléation hétérogène ne modifie pas significativement les propriétés mécaniques, sauf pour la déformation à la rupture. Néanmoins, les propriétés de transfert sont diminuées. Dans la deuxième partie, l’effet du temps de recuit pour modifier la cristallinité du PLA seul et avec 3% de talc a été étudié. Dans ce cas, on constate que la perméabilité aux gaz et le coefficient de diffusion sont réduits en augmentant le temps de recuit (jusqu'à 40 minutes). On constate également que l'augmentation de la cristallinité ne modifie pas les propriétés mécaniques, à l'exception du module de Young. Enfin, la température de recuit pour améliorer la cristallinité du PLA seul ou avec 3% de talc a été étudiée. Bien que la perméabilité aux gaz et le coefficient de diffusion aient diminué en augmentant la température de traitement (de 60 à 120°C), l'augmentation de la cristallinité finale n’a pas changé de manière significative les propriétés mécaniques, à l'exception du module de Young et la déformation à la rupture pour le composite ayant 3% de talc. / The main purpose of this work is to determine the effect of crystallinity on the gas permeation of polymer films. In particular, polylactic acid (PLA) was used as the matrix and various gases were selected (nitrogen, carbon dioxide, hydrogen, methane and oxygen) for the gas transport properties. To this end, the work was divided into three parts. In the first part, talc was used as a nucleating agent to modify the crystallinity of PLA. In this case, it was noted that the gas permeability and the diffusion coefficient were reduced with increasing talc content (0-3% by weight). It was also observed that increased crystallinity was related to heterogeneous nucleation, but had limited effect on mechanical properties, with the exception of strain at break. However, the transport properties were decreased. In the second part, annealing time was used to modify PLA crystallinity with 0% and 3% talc. In this case, it was found that gas permeability and diffusion coefficient were lowered with higher annealing time (up to 40 min). It was also observed that higher crystallinity did not change the mechanical properties except for the Young’s modulus. Finally, annealing temperature was modified to improve the crystallinity of neat PLA and 3% talc composite. While gas permeability and diffusion coefficient both decreased with increasing annealing temperature (from 60 to 120°C), crystallinity changes did not significantly modify the mechanical properties, except for the Young’s modulus and strain at break of the 3% talc composite.
195

Modification chimique de polymères par des dérivés acyloxyimides en extrusion réactive / Chemical modification of polymers by acyloxyimide derivatives in reactive extrusion

Rakotonirina, Mamy Daniel 20 July 2018 (has links)
La fonctionnalisation post-polymérisation ou post-fonctionnalisation est une technique qui permet d’apporter des propriétés spécifiques à des polymères dont les caractéristiques intrinsèques sont limitées pour une application donnée. Parmi les différentes stratégies de post-fonctionnalisation, une des plus courantes est le greffage radicalaire en milieu fondu par extrusion réactive (T > 160 °C). Dans ce type de procédé, un précurseur de radicaux appelé agent de greffage est utilisé afin de greffer des unités fonctionnelles sur les chaines de polymère. A ce jour, ce sont les radicaux à base de peroxydes qui sont employés. Cependant, ces derniers engendrent souvent des réactions de réticulation de chaines qui réduisent l’efficacité du processus. Afin de surmonter ces inconvénients, il est alors important de développer de nouvelles structures pertinentes. Dans ce contexte, les travaux de recherche que nous avons entrepris dans cette thèse concernent la conception et l’étude de nouveaux agents de greffage dérivés d’acétoxyphtalimide (NAPI) pour la post-fonctionnalisation de polymères. Afin d’atteindre ces objectifs, notre démarche a été basée sur une approche multidisciplinaire comportant une étude théorique par modélisation moléculaire et une approche expérimentale incluant la synthèse et l’étude de réactivité des nouvelles structures. Par la suite, des essais de post-fonctionnalisation de polyéthylène, de polyamide ainsi que de poly(acide lactique) par ces nouveaux agents de greffage ont été réalisés. Ces essais ont montré des résultats prometteurs à l’utilisation de ces nouveaux composés par rapport aux peroxydes dans les systèmes d’extrusion. / Post-functionalization is a technique which allows to introduce specific properties to polymers whose intrinsic characteristics are limited for a defined application. It has become an appropriate tool to answer the strong demand for performance materials that is constantly growing. Among the post-functionalization methods, one of the most exploited is the radical grafting of the polymers in the molten state by reactive extrusion (T> 160 ° C). In this type of process, a radical precursor called grafting agent is used to graft functional units (monomers) onto the polymer backbone. In this context, the conventional grafting agents used in extrusion are peroxides. However, the radicals generated by peroxide compounds often lead to side reactions, particularly crosslinking reactions of the polymer chains which limit the efficiency of the process. Thus, finding a new family of grafting agents remains a challenge to optimize these extrusion systems. In this research work, the main objective is to use new grafting agents based on acetoxyphthalimide (NAPI) for extrusion. To reach this goal, our strategy is based on a multidisciplinary approach which presents a theoretical study by chemical modeling and an experimental approach by the synthesis and the reactivity study of the targeted structures. To validate the concept, polyethylene, polyamide and polylactic acid post-functionalization tests through these new grafting agents have been carried out. The results obtained have shown that these NAPI derivatives are efficient to graft monomers and to reduce the crosslinking reaction compared to peroxide agents.
196

Cisplatine : une vieille molécule pour de nouveaux défis. : développement d’une prodrogue macromoléculaire multifonctionnelle applicable au traitement local du glioblastome / Cisplatin : an old drug to tackle new challenges : development of a multifunctional macromolecular prodrug for the local treatment of glioblastoma

Lajous, Hélène 22 May 2018 (has links)
Le glioblastome constitue la tumeur primitive maligne la plus fréquente et la plus agressive du système nerveux central, caractérisée par un pronostic sombre. L’infusion locale dans le parenchyme cérébral du cisplatine a présenté des résultats encourageants sur des modèles précliniques. La nanovectorisation permet de concentrer l’efficacité thérapeutique d’agents anticancéreux à leur cible. Leur fonctionnalisation par des unités d’imagerie offre la possibilité de suivre de façon non invasive par imagerie par résonance magnétique (IRM) leur biodistribution au sein du tissu lésé. Dans cette optique, un copolymère tribloc amphiphile biocompatible a été synthétisé par polymérisations par ouverture de cycle successives à partir d’un oxyde de polyéthylène (PEO). Après micellisation dans l’eau, des complexes de gadolinium ont été greffés sur la couronne de PEO et les fonctions carboxylates situées en périphérie du coeur micellaire se sont réticulées sur le cisplatine, conduisant à la formation d’une prodrogue macromoléculaire de taille nanométrique stable dans le temps. Le potentiel de ces nanoparticules bifonctionnelles comme agents de contraste IRM a été exploré à haut champ magnétique. Une telle vectorisation du cisplatine a en outre permis d’augmenter de façon significative l’accumulation du platine dans deux lignées humaines de glioblastome ainsi que la formation d’adduits à l’ADN par rapport à la drogue libre. L’implication de mécanismes biologiques sous-jacents à cette étude pose la question de l’existence d’autres cibles alternatives critiques des dérivés du platine, remettant en cause le paradigme établi depuis un demi-siècle définissant l’ADN comme la cible ultime du cisplatine. / Glioblastoma is the most frequent and aggressive primary malignant tumor of the central nervous system with a gloomy prognosis. Local infusion of cisplatin within the brain parenchyma exhibited promising results in preclinical models. Nanovectorization of anticancer agents even promotes the concentration of their therapeutic efficiency on their target. Anchorage ofimaging moieties on such smart drug delivery systems further enables the non-invasive monitoring of their biodistribution within the damaged tissue by magnetic resonance imaging (MRI). From this perspective, a biocompatible amphiphilic triblock copolymer was synthesized by successive ring-opening polymerizations from a polyethylene oxide (PEO). After micellization in water, gadolinium complexes were grafted to the PEO corona and the carboxylate functions located at the surface of the micelle’s core were able to cross-link with cisplatin. A stable nano-sized macromolecular prodrug was therefore recovered. Relaxomety measurements at a high magnetic field confirmed the intrinsic potential of these hybrid nanoparticles as alternative MRI contrast agents. Besides, cisplatin vectorization allowed for substantially increasing the accumulation of platinum compounds in two human glioblastoma cell lines as well as the subsequent formation of DNA adducts in comparison with the free drug. Biological mechanisms below this study raise the question whether critical alternative targets of platinum derivatives might exist, thus undermining the old-established paradigm that defines DNA as the ultimate target of cisplatin.
197

Jämförande LCA av engångssängkläder och tvättbara sängkläder i sjukvården / A comparative LCA of disposable and washable beddings used in healthcare

Strömner, Fredrik January 2014 (has links)
Inom sjukvården används – precis som överallt där människor sover – sängkläder av hygienskäl. Problem med smittspridningar av typen multiresistenta bakterier (MRSA) och spridning av andra sjukdomar har drivit företag som Cellcomb i Karlstad AB till att utveckla engångssängkläder för att förhindra detta. Engångssängkläderna är skyddade av en biofilm som ska ge ökat skydd mot bakterier och fungerar som en barriär så att inte vätska tränger igenom. Problemet är att det inte finns mycket till underlag för hur engångssängkläderna står sig mot vanliga sängkläder ur miljösynpunkt. I dagsläget använder sjukhus traditionella sängkläder till sina patienter och sedan transporteras dessa till tvätteri och tvättas. Att tvätta och torka sängkläder är energikrävande och ett alternativ till detta skulle kunna vara att använda engångssängkläder. En förenklad LCA gjordes för att ta reda på om sängkläder tillverkade av bomull och polyester eller engångssängkläder tillverkade av polypropylen alternativt viskosmaterialet Tencel är det mest miljövänliga. För att ta reda på det gjordes studiebesök och data samlades in genom en litteraturstudie och från företag. Resultaten visade att i ett grundfall med Centralsjukhuset i Karlstad var energianvändningen för de tvättbara sängkläderna lägre än Tencel och försumbart lägre än polypropylen. Flera fall med känslighetsanalyser gjordes för att undersöka hur indata påverkade resultaten. Fallen visade att det kan variera vilket av alternativen som blir mest gynnsamt, framför allt när det gäller vilken typ av energi tvätteriet använder. Engångssängkläderna av Tencel visade sig vara bäst när det gällde andel förnybar energi följt av de tvättbara sängkläderna och sist polypropylen. Ur ett ekotoxicitets- och vattenanvändningsperspektiv blev båda engångssängkläderna mer gynnsamma än de tvättbara sängkläderna. Två slutsatser kan dras utifrån den här studien: de tre alternativen är likvärdiga energimässigt utifrån energianvändning, andel förnybar energi och de fallstudier som gjorts, men att engångssängkläderna står sig bättre när det gäller ekotoxicitet samt vattenanvändning. Den andra slutsatsen är att resultaten är fallberoende. En utökad studie skulle kunna göras med fler viktiga miljöparametrar och fler känslighetsanalyser. / In healthcare – as in any other place where people sleep – beddings are used for hygiene reasons. Problems with spreading of bacteria diseases such as multi resistant bacteria (MRSA) and various other diseases have pushed companies like Cellcomb i Karlstad AB to develop disposable beddings in order to prevent this. These disposable beddings are protected with a biofilm which serves as a barrier, preventing liquids to pass through. The problem is that there is not much information about how these beddings perform from an environmental perspective. At present, hospitals are using traditional beddings for their patients and are then transported to laundries for washing. This is an energy intensive process and as an alternative, disposable beddings could be used. A simplified LCA was used to find out if beddings made out of cotton and polyester or disposable beddings made out of polypropylene or a viscose material called Tencel was the most favourable from an environmental perspective. To achieve this, various study visits were performed along with a literature study and data collection from companies. The results showed that for a basic case performed with Centralsjukhuset i Karlstad the washable beddings used less energy than Tencel and negligibly less energy than polypropylene. Several case studies were performed in order to examine how different data could alter the results. The case studies showed that which of the alternatives became the most favourable varied depending on the case, especially regarding which kind of energy was being used in the laundry. The disposable beddings made out of Tencel proved to be the best alternative regarding the use of renewable energy, followed by the washable beddings and last polypropylene. From a perspective of eco toxicity and water use both of the disposable beddings turned out more favourable. Two conclusions could be drawn from this study: the alternatives are equally favourable regarding energy use, renewable energy use and the case studies that were performed, but the disposable beddings are more preferable concerning eco toxicity and water use. The second conclusion is that the results depend on which case is studied. An expanded study could be performed using more environmental parameters.
198

Erstellung einer Sachbilanz-Studie und Modellierung des Lebensweges von Operationstextilien

Mielecke, Torsten 30 November 2009 (has links) (PDF)
Die vorliegende Ausgabe beschäftigt sich mit dem Thema „Erstellung einer Sachbilanz-Studie und Modellierung des Lebensweges von Operationstextilien". Das Ergebnis der Sachbilanz ist, dass die Mehrwegtextilien, im Vergleich zu den Einwegtextilien, einen geringeren Stoff- und Energiefluss erzeugen. Die Modellierung der Lebenszyklen ist in der Software Umberto vorgenommen. Sie visualisiert die Stoffflüsse zwischen den einzelnen Modulen des Lebensweges sehr gut. Es konnte verdeutlicht werden, dass der Wasserfluss der mengenmäßig größte Stoffstrom ist. Die größten Wasserverbräuche werden bei den Mehrwegtextilien in der Wäscherei und der Textilveredlung getätigt; bei den Einwegtextilien sind dies hingegen die Textilveredlung und die Kunststoffherstellung. Als Ergebnis der gesamten Überlegungen wird festgehalten, dass die erstellte Sachbilanz einen guten Hinweis auf die Umweltverträglichkeit der OP-Textilien gibt. Eine anschließende Ökobilanz, aufbauend auf den gewonnenen Daten, könnte die ermittelten Ergebnisse bestätigen.
199

Materialval och design av klimatsmart rullgardin

Nehmé, Yasmine, Karlsson, Cecilia January 2017 (has links)
Syftet med examensarbetet har varit att hitta lämpliga textila material för en klimatsmart rullgardin med flera olika skikt skapad av företaget Climate Curtains, samt att ta fram en väl genomtänkt design som är anpassad för miljön den är tänkt att hänga i, nämligen skolor och kontor. Den klimatsmarta rullgardinen ska ha ett absorberande mattsvart material närmast glasfönstret för att fånga upp UV-strålning och därmed bli varmt. Värmen ska sedan föras in i rummet med hjälp av fläktar som sitter monterade inuti gardinstången. En solcellsfilm ska även fästas på skiktet närmast fönstret och har därför tagits med i beräkningarna, dock är solcellsfilmen fortfarande under utveckling. Tanken med solcellsfilmen är först och främst att den ska förse fläktarna med energi men även webbelysning eller laddning av mobil och dator vid överflöd av energi ska vara möjligt. Rullgardinen ska även ha ett vitt reflekterande material in mot rummet för att möjligheten att vända gardinen ska finnas. Under sommartid kan den vända gardinen istället reflektera bort UV-ljus. Mellan dessa två skikt ska ett antal mellanskikt hänga för att erhålla bättre isoleringsegenskaper samtidigt som buller och oljud minskas. Det har även varit relevant att undersöka om flamskyddsmedel bör användas eftersom att gardinen ska hänga i offentliga miljöer. Examensarbetet har bestått av litteraturstudier och praktiska experiment. Experimenten som utfördes var nöthärdighets-, flexibilitets-, reflektionstest samt säkerställning av färg. Materialen som har undersökts har alla varit gjorda av 100% polyester och två alternativa material valdes för vardera skikt. Polyester valdes till alla skikt dels för att det är billigt och dels för att polyester visade sig ha mycket goda egenskaper för de krav som ställdes. Ytterskiktet som är närmast glasfönstret samt innerskiktet in mot rummet valdes till vävar med olika bindningar. Till ytterskiktet jämfördes en tvåskaftsväv med en kypertväv där tvåskaftsväven uppvisade bäst resultat i alla testerna. Kypertväven färgade av sig och nöttes ner i nöthärdighetstestet vilket inte tvåskaftsväven gjorde. Flexibilitets- och reflektionstestet visade goda resultat för båda vävarna. I reflektionstestet pikade tvåskaftsvävens reflektionskurva en aning i det röda spektrat, vilket innebar att den hade en viss röd nyans i sig. Säkerställning av färg gick inte att utföra för de svarta vävarna då svart färg finns i oändligt många olika nyanser. Till det vita innerskiktet jämfördes en tvåskaftsväv med en satinväv. Båda vävarna hade relativt lika resultat i nöthärdighets- samt flexibilitetstestet men satinväven fick bättre resultat i reflektionstestet vilket var avgörande. Vid säkerställning av färg testades den vita färgen i ett ljusskåp i olika ljus för att kontrollera dess vithet. Det visade sig att båda vävarna innehöll optiskt vitmedel vilket även framkom i reflektionstestet då de reflekterade över 100 %. Till mellanskikten jämfördes två olika nonwovenmaterial som består av ihåliga polyesterfibrer. Ihåliga fibrer ha bra ljudabsorption vilket kan vara bra i miljöer såsom skolor och kontor där det kan vara mycket buller och höga ljudnivåer. Det ena materialet vägde 100g/m2 och det andra 250g/m2. Ett nöthärdighets- och flexibilitetstest utfördes på dessa nonwovenmaterial. De båda fick godkänt resultat i flexibilitetstestet men nonwoven 100 höll inte måttet i nöthärdighetstestet varav nonwoven 250 är mest lämpat för rullgardinen. Litteraturstudiens resultat tyder på att det inte finns några krav på flamskyddsmedel i gardiner i offentlig miljö utan endast rekommendationer. Det är alltså upp till företag att bestämma om de vill flamskydda gardinerna. De finns en mängd olika flamskyddsmedelsvarianter men de har alla en sak gemensamt och det är att de är fettlösliga och långlivade, vilket gör att de är svåra att bryta ned. Gardinen designades i en stilren och klassisk design. En kornisch utformades dels för att dölja gardinstången och dels för att erhålla ett snyggare helhetsintryck. Gardinen kommer att ha en fåll längst ned på det yttre och det inre skiktet. Inuti fållen kommer en plastskena läggas för att få tyngd i materialet och därmed ett bättre fall. Fållen ger även gardinen en lyxigare känsla. Resterande kanter på alla materialen för alla skikt valdes att lasras. Med laserskärning erhålls fina kanter som inte fransar sig alls och laserskärning garanterar även att det inte blir någon nötning på produkten under skärningen vilket är fördelaktigt på en rullgardin då den rullas upp och ner mycket. Skisser ritades upp i Kaledo Style för att få en tydligare bild av hur rullgardinen kan komma att se ut. Eventuella tillval, mönster på det vita skiktet samt solceller i olika storlekar, kan även göras på gardinen beroende på kundens önskemål. För att kunna applicera mönstret på det textila materialet undersöktes tre alternativa tryckmönstermetoder; rollerprinting, roterande screentryck samt digital inktryck. De två sistnämnda lämpar sig bäst för ändamålet. / The aim of the thesis was to find the optimal textile materials for a climate-smart blind with multiple layers created by the company Climate Curtains. The aim was also to develop a well thought out design that is adapted to the environments it is supposed to hang in, which are schools and offices. The climate-smart blind should have an absorbing black matte material closest to the glass window to capture UV radiation and thereby become warm. The heat will then be brought into the room with the help of fans that are mounted inside the curtain rod. A solar cell film should also be attached to the layer closest to the window and have therefore been included in the calculations, however, the solar film is still under development. The idea of a solar cell film is first and foremost that it will provide fans with energy but also charging of mobile and computer at the abundance of energy. The blind must also have a white reflective material into the room for the possibility of turning the curtain in the summer. This leads to a reflection of the UV light instead of absorption. Between these two layers, a number of intermediate layers will hang to provide isolation of air and noise reduction. The amount of flame retardants have also been relevant to examine because the curtain will hang in public places. There are no requirements in public places when it comes to flame retardants, but there are recommendations published. A solar cell film should also be attached to the layer closest to the window and have therefore been included in the calculations. However, the solar film is still under development. The work has consisted of literature studies, laboratory work and compilation of discussion and results. The laboratory work included abrasion resistance-, flexibility-, reflection test and a test to secure the colors. The materials studied have all been made of 100% polyester and two alternative materials were chosen for each layer. Polyester was chosen to all layers partly because it is cheap and secondly because polyester was found to have very good qualities for the demands made. The outer layer closest to the window and the inner layer into the room consists of fabrics made of weaves with different constructions. For the outer layer a plain weave and a twill weave were chosen to be compared against each other. The plain weave got the best results in all of the tests. For the inner layer a satin weave and a plain weave were compared, and the satin weave got the best results in all the tests. Furthermore, the layers in between the weave textiles are made of hollow polyester fibers as a nonwoven material. Hollow fibers have good sound absorption, which can be useful in environments such as schools and offices where there may be much noise and high sound levels. One material weighing 100 g/m2 and the other 250 g/m2. An abrasion resistance- and flexibility test was conducted on these nonwoven materials. They both got approved results in the flexibility test. However, nonwoven 100 was not good enough in the abrasion resistance test and therefor nonwoven 250 is the most suitable middle layer for the blind. The curtain was designed in a stylish and classic design. A cornice designed partly to hide the curtain rod and partly to obtain a more attractive overall impression. The blind will have a hem at the bottom of the outer and the inner layer. Inside the hem a plastic splint is added to give better stability. The hem also gives the curtain a luxurious feel. The remaining edges on all materials for all layers were chosen to be lasered. With laser cutting fine edges are obtained.4Sketches were drawn up in Kaledo Style to get a clearer picture of how the blind could look like. Any optional patterns on the white layer and the solar cells of different sizes, can also be made on the curtain, depending on customer requirements. In order to apply the pattern to the textile material three alternative methods was studied; roller printing, rotary screen printing and digital ink print. Screenprinting and digital printing was best suited for the purpose.
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Effect of Tris, MOPS, and phosphate buffers on the hydrolysis of polyethylene terephthalate films by polyester hydrolases

Schmidt, Juliane, Wei, Ren, Oeser, Thorsten, Belisário-Ferrari, Matheus Regis, Barth, Markus, Then, Johannes, Zimmermann, Wolfgang January 2016 (has links)
The enzymatic degradation of polyethylene terephthalate (PET) occurs at mild reaction conditions and may find applications in environmentally friendly plastic waste recycling processes. The hydrolytic activity of the homologous polyester hydrolases LC cutinase (LCC) from a compost metagenome and TfCut2 from Thermobifida fusca KW3 against PET films was strongly influenced by the reaction medium buffers tris(hydroxymethyl)aminomethane (Tris), 3-(N-morpholino)propanesulfonic acid (MOPS), and sodium phosphate. LCC showed the highest initial hydrolysis rate of PET films in 0.2 M Tris, while the rate of TfCut2 was 2.1-fold lower at this buffer concentration. At a Tris concentration of 1 M, the hydrolysis rate of LCC decreased by more than 90% and of TfCut2 by about 80%. In 0.2 M MOPS or sodium phosphate buffer, no significant differences in the maximum initial hydrolysis rates of PET films by both enzymes were detected. When the concentration of MOPS was increased to 1 M, the hydrolysis rate of LCC decreased by about 90%. The activity of TfCut2 remained low compared to the increasing hydrolysis rates observed at higher concentrations of sodium phosphate buffer. In contrast, the activity of LCC did not change at different concentrations of this buffer. An inhibition study suggested a competitive inhibition of TfCut2 and LCC by Tris and MOPS. Molecular docking showed that Tris and MOPS interfered with the binding of the polymeric substrate in a groove located at the protein surface. A comparison of the Ki values and the average binding energies indicated MOPS as the stronger inhibitor of the both enzymes.

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