Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With the highly utilization of phenolic compounds and surfactant for several industrial sectors have been increasing the amount of unloading of these pollutant in the effluents, creating pollution. The sorption has getting attention for being an encouraging method for the removing of the chemical pollutants, found on the aqueous effluents. This thesis has the propose of evaluating the capacity of the sorption of the surfactant dodecyl benzene sodium sulfate (SDBS) in crosslinked chitosan beads with Epichlorohydrin (QUIT-EP) and the dichlorophenol-2,6-indophenol (DCFI) found in fish scales (Micropogonias furnieri) Changed with glutaraldehyde and chitosan. The chitosan spheres (QUIT-EP) present 67,8% of anionic surfactant remotion SDBS and the croaker fish scale (ESC-QUIT) removed 70,2% of the DCFI in the aqueous solution, proving the efficiency of these materials in the transference of the studied pollutants. / Com a intensa utilização de compostos fenólicos e surfactantes por vários setores industriais, têm aumentado bastante, as quantidades de descargas destes poluentes em efluentes, gerando poluição. A adsorção, por ser um método promissor, vem sendo muito utilizada na remoção de poluentes químicos presentes em efluentes aquosos. Esta tese teve por objetivo avaliar a capacidade de sorção do surfactante dodecilbenzenossulfonato de sódio (SDBS) em esferas de quitosana reticuladas com epicloridrina (QUIT-EP) e do diclorofenol-2,6-indofenol (DCFI) em escamas do peixe corvina (Micropogonias furnieri) modificadas com glutaraldeído e quitosana. As esferas de quitosana (Quit-EP) apresentaram 67,8% de remoção do surfactante aniônico SDBS e as escamas do peixe corvina (ESC-QUIT) removeram 70,2% do DCFI de soluções aquosas, comprovando que esses materiais são eficientes na remoção dos poluentes estudados.

Dans l’industrie automobile, la tâche de dimensionnement des faisceauxélectriques consiste à définir au plus juste la section du conducteur métallique, ce qui augmente l’échauffement du câble par effet Joule. Or, les polymères sont les matériaux d’isolation les plus utilisés malgré leur grande sensibilité au vieillissement thermique. C’est pourquoi leur durabilité en environnement automobile doit être déterminée pour pouvoir ensuite être prise en compte lors du dimensionnement des faisceaux électriques. Dans ce but, nous avons analysé le vieillissement thermique de deux gaines d’isolation en PVC et PELX dans l’air aux températures des essais de qualification (typiquement entre 100°C et 200°C). Dans le cas du PVC, le principal mécanisme de vieillissement est la perte physique du plastifiant. La fragilisation du matériau intervient orsque la concentration de la phase de plastifiant non-dissoute, qui est ispersée sous forme de nodules dans la matrice PVC faiblement plastifiée, atteint une valeur critique de l’ordre de 0,2 mol.L-1. En revanche, dans le cas du PELX, l’oxydation conduit à la fragilisation du matériau au terme de la période d’induction, c’est-à-dire dès que la totalité des antioxydants a été consommée. Pour chaque gaine d’isolation, un modèle cinétique a été dérivé des mécanismes de vieillissement et un critère de fin de vie structural a été établi. Ce modèle donne accès au potentiel de vie restant et à la durée de vie des câbles électriques en conditions de service. / In the automotive industry, the issue of electrical harness dimensioning consists in an optimal definition of the cross-section of metallic conductors, which increases the wire heating due to Joule effect. However, polymers are the most used materials for insulation despite their high sensitivity to thermal ageing. That is the reason why their durability must be determined in automotive environment to be then taken into account during the dimensioning of electrical harness. For this purpose, we analyzed the thermal aging of two insulation sheaths made of PVC and XLPE in air at temperatures of qualification tests (typically between 100°C and 200°C). For PVC, the main ageing mechanism is the physical loss of plasticizer. The material embrittlement occurs when the concentration of the non-dissolved plasticizer phase, which is dispersed as nodules in the weakly plasticized PVC matrix, reaches a critical value of about 0,2 mol.L-1. In contrast, for XLPE, oxidation leads to material embrittlement at the end of the induction period, i.e. when the totality of antioxidants has been consumed. For each insulation sheath, a kinetic model was derived from the ageing mechanisms and a structural end-of-life criterion was established. This model gives access to the remaining life potential and lifetime of electrical cables in service conditions.

In diesem Beitrag wird eine Organisationsanalyse hinsichtlich der Kooperation vernetzter Kleinunternehmen und Freelancer dargestellt. Ziel ist, den Begriff der virtuellen Organisation zu definieren und die verschiedenen Kooperationsformen und Besonderheiten vernetzter Kleinunternehmen und Freelancer zu beschreiben. Neben einer Literaturstudie wurden dazu Projektausschreibungen auf einer Kooperationsplattform im Internet analysiert und eine Reihe von felderkundenden Interviews durchgeführt. Daraufhin wurde eine detaillierte Analyse der Arbeitsorganisation in einem Projekt eines virtuellen Netzwerkunternehmens vorgenommen. Die Ergebnisse verschaffen einen Einblick in die Rollenvergabe und Arbeitsteilung zwischen den Partnern und in die Rolle(n) des Koordinationsunternehmens sowie in die potentiellen Vor- und Nachteile einer solchen zentralen Koordination der autonomen Partner.

No description available.

My work focuses on taking waste wire-grade PVC = poly(vinyl chloride) and waste XLPE = cross-linked polyethylene and recycle them into small wire/cable spool technology in order to reduce waste cost and reduce cost of spool production. The PVC and XLPE were provided by Encore Wire Corp. of McKinney, TX; they have also defined the standard to which I am comparing my results. The end goal is to incorporate as much PVC and XLPE into the spools while maintaining material toughness, impact resistance, as well as cost-effectiveness in the implementation of the waste materials. The work has been divided into two primary sections, the first is focused on improving material strength through the addition of ceramic fillers. The second section is focused on adding PVC and XLPE into a stronger and highly cohesive polymer matrix and optimizing the concentration of the waste products. Since XLPE is non-polar while PVC is strongly polar, compatibilizers such as CPE (chlorinated polyethylene) and MA-DCP (maleic anhydride with dicumyl peroxide) were used to improve interactions between polar and non-polar constituents. Testing involved the tensile mechanical properties, tribology and thermal properties, namely dynamic mechanical analysis (DMA) and evaluation of thermal degradation by thermogravimetric analysis (TGA). Combining PVC and XLPE together is not economically feasible with current compatiblizers. At the same time, introduction of PVC waste or XLPE waste with sufficient properties of the resulting composites is doable.

No description available.

Under senaste decennierna, har intresset kring implantat från naturliga och syntetiska polymerer ökat markant i samband med en ökad marknadsefterfrågan på vävnadsdonationer. Detta har lett till efterforskningen av nya in-situ formerande geler med formbevarande egenskaper in-vivo. Extracellulära matrisen (ECM) innehåller flertal makromolekylära komponenter med stödjande och nätverksformerande egenskaper, då de ofta är essentiella strukturella konstituenter i biologiska system. Den huvudsakliga beståndsdelen i ECM-nätverket, kollagen typ-1, har undersökts som en kandidat för utvecklingen av nya modifierade biomaterial med cellförökande-, biokompatibla-, icke-svällande samt injicerbara egenskaper. I detta projekt var grisderiverat kollagen modifierat med furfuryl glycidyl eter, och tvärbundet med 10 kDa 8-armad PEG-malimid, vilket genomgick kovalenta Diels-alder klick-reaktioner. Fyra formuleringar användes i experimenten, baserat på de stökiometriska förhållandet mellan furan och malimid i det kemiskt modifierade kollagenet. Dessa kollagen-baserade hydrogeler undersöktes baserat på 4 wt% löst kollagen, med avseende på reologiska-, mekaniska-, bionedbrytbara och svällningsegenskaper.  Resultaten indikerar att en ökning i fastfas-mängd ledde till en förhöjning i hydrogelens styvhet. Detta kunde observeras genom en ökad lagringsmodul (G’) under reologiska mätningar. Samtidigt indikerade mätningarna att sprödheten av hydrogelen ökade i korrelation med ökningen av styvheten.  Vidare drogs slutsatsen att kovalenta interaktionerna är enbart delvis ansvarig för ökningen av G’. Jämförelser med tan delta och kritiska töjningen visade att det fanns fysiska interaktioner mellan polymererna vilket också bidrog till ökningen av G’ för gelformuleringar som innehöll furan-till-malimid förhållanden på 1:1 och 1:4. Dessa fysiska interaktioner tros härstamma från en ökning av hydrofobiska effekter mellan kollagen kedjorna, då agglomerering och löslighetssvårigheter i vattenlösningar observerades i flertal experiment. Kollagen-PEG-Malimid hydrogelen var också injicerbar genom 15G kanyler, nedbrytbar in-vitro i närvaro av kollagenas, och uppvisade låg svällning i vatten. Inga cellexperiment genomfördes, och därav kunde inga slutsatser dras i hydrogelens cellförökande egenskaper. Däremot har tidigare arbete av Dr Jamadi visat att kollagen-PEG-malimid hydrogel med 2 vikt% haft kapacitet att inkapsla celler. Detta kan vara en indikation att högre viktprocent av gelen också kan uppvisa samma effekt vid framtida försök.Sammanfattningsvis, kunde slutsatsen dras att hydrogelen uppvisar flertal av de spekulerade, samt några av de eftertraktade egenskaperna hos en injicerbar hydrogel som potentiellt kan användas kliniskt. / In recent decades, the interest in implants manufactured from natural and synthetic polymers has grown as the demand for tissue donations has increased. This process has led to the pursuit of new, in-situ forming gels with shape-retaining properties in-vivo. The extracellular matrix (ECM) contains several macromolecular constituents with scaffold forming capabilities and is an inherent part of the body. The main component in the ECM-scaffold, collagen type-I, has been investigated as a candidate for novel modified biomaterials with cell proliferating, biocompatible, non-swelling, and injectable properties. Collagen was modified with furfuryl glycidyl ether and crosslinked with 10 kDa 8-arm PEG-maleimide, which undergoes Diels-alder covalent click-type reactions. Four formulations were used, based on a stoichiometric ratio of furan to maleimide (1:1-1:4). These materials' properties were evaluated at 4 wt% collagen for rheological-, mechanical-, biodegradability and swelling characteristics. The results indicated that an increase in solid content improved stiffness in the hydrogel.  This was observed by an increase of storage modulus (G’) during rheological measurements. The same measurements also indicated that the hydrogel showed an increase in brittle characteristics correlated with higher solid content.  Furthermore, it was concluded that the covalent interactions are partly responsible for the increase of G’. Comparisons in tan delta and critical strain showed that there are physical interactions that cause the increase in moduli for gel formulations containing furan to maleimide ratios of 1:1 and 1:4. These physical interactions are thought to stem from the increase in hydrophobic effects of the modified collagen, as agglomeration and solubility issues in aqueous solutions are observed in multiple experiments.  Collagen-PEG-maleimide hydrogel was also injectable through a 15-gauge needle, degradable in-vitro, and showed low swelling. No cell experiments were performed, and hence no conclusions could be made of this aspect of the hydrogel. However, work has been performed by Dr Jamadi, which indicates that the Collagen-PEG-Maleimide hydrogel with lower weight percentages allows for cell encapsulation. Hence, it could be concluded that several characteristics of tissue mimetic material were met with this hydrogel.

Sulfonated poly(arylene ether sulfone)s as ion conductive copolymers have numerous potential applications. Membranes cast from these copolymers are desirable due to their good chemical and thermal stability, excellent mechanical strength, satisfactory conductivity, and excellent transport properties of water and ions. These copolymers can be used in a variety of topologies. Structure-property-performance relationships of these membranes as candidates for electrolysis of water for hydrogen production and for purification of water from dissolved ions have been studied. Linear and multiblock sulfonated poly(arylene ether sulfone)s are potential alternative candidates to Nafion membranes for hydrogen gas production via electrolysis of water. In this investigation, these copolymers were prepared from the direct polymerization of di-sulfonated and non-sulfonated comonomers with bisphenol monomers. In systematic investigations, a series of copolymers with modified properties were synthesized and characterized by changing the ratio of the sulfonated/non-sulfonated comonomers in each reaction. These copolymers were investigated in terms of mechanical stability, proton conductivity and H2 gas permeability at a range of temperatures and under fully hydrated conditions. A multiblock copolymer was synthesized and evaluated for its potential as membranes for electrolysis of water and for fuel cell applications. The multiblock copolymer contained some fluorinated repeat units in the hydrophobic blocks, and these were coupled with a fully disulfonated hydrophilic block prepared from 3,3'-disulfonate-4,4'-dichlorodiphenyl sulfone and biphenol. After annealing, the multiblock copolymer showed enhanced proton conductivity and a more ordered morphology in comparison to the random copolymer counterparts. At 90 oC and under fully hydrated conditions, improved proton conductivity and controlled H2 gas permeability was observed. Finally, the performance of the multiblock copolymer, which was measured as the ratio of proton conductivity to H2 gas permeability, was improved when compared to the state-of-the-art membrane, Nafion 212, by a factor of 3. In another systematic study, two series of random copolymers were synthesized and characterized, and then cast into membranes to evaluate for electrolysis of water. One series contained solely hydroquinone as the phenolic monomer, while the second series contained a mixture of resorcinol and hydroquinone as phenolic comonomers. The polymers that contained only the hydroquinone monomer showed exceptionally good mechanical properties due to the para-substituted comonomer in the composition of the polymer. In the resorcinol-hydroquinone series, gas permeability was constrained due to the presence of 25% of the meta-substituted comonomer incorporated into its structure. Low gas permeability and high proton conductivity at elevated temperatures were obtained for both the linear random and multiblock copolymers. Performance of these copolymers was superior to Nafion at elevated temperatures (80-95°C). In order to enhance the durability of these materials in their hydrated states at elevated temperatures, the surfaces of these copolymer films were treated with fluorine gas. In comparison with pristine non-fluorinated membranes, the modified membranes showed decreased water uptake and longer durability in Fenton's reagent. A series of linear and crosslinked copolymers were investigated with respect to their potential for use as membranes for desalination of water by electrodialysis and reverse osmosis. The crosslinked membranes were prepared by reacting controlled molecular weight, disulfonated oligomers that were terminated with meta-aminophenol with an epoxy reagent. The oligomers had systematically varied degrees of disulfonation and either 5000 or 10,000 Da controlled molecular weights. Membrane casting conditions were established to fabricate highly crosslinked systems with greater than 90% gel fractions. At such a high gel fraction, the water uptake of the crosslinked membranes was lower than that of the linear biphenol-based, disulfonated random copolymer with a similar IEC. Among these series of copolymers, it was shown that the crosslinked membranes cast from the oligomers with 50% degree of disulfonation and a molecular weight of 10,000 Da had the lowest salt permeability of 10-8 cm2/sec. For desalination applications, a comonomer was synthesized with one sulfonate substituent on 4,4'-dichlorodiphenyl sulfone. This new monosulfonated comonomer allows for even distribution of the ions on the linear copolymer backbone, and this may be important for controlling ion transport. Mechanical tests were conducted on the membranes while they were submerged in a water bath. The ultimate strength of a fully hydrated copolymer with an IEC of 1.36 meq/g was approximately 60 MPa with an elongation at break of 160%. Moreover, in a monovalent/divalent mixed salt solution, the monosulfonated linear copolymer exhibited a constant Na+ passage of less than 1.0%. / Ph. D. / Purification systems have become an increasingly important scientific and technological need for millions around who face water shortages and/or impure sources of potable water. In response, water purification and hydrogen gas production have been widely used to produce pure products from a variety of water sources. In general, current state-of-the-art methods in separation technologies feature two major drawbacks: they are energy intensive and costly processes. In response to the growing need for purified water or pure hydrogen gas for energy generation, polymeric materials are increasingly used in the form of membranes to produce a purer product and overcome the hindrances associated with current energy intensive and inefficient methods. These membranes serve as a barrier for unwanted species, while at the same time allowing the desired species to pass through. Under proper conditions, these purification or chemical processes would generate pure materials that can be used on demand. The chemistry of candidate polymeric materials is extremely important to design a membrane with desired properties. Therefore, the principal goals of this investigation were to synthesize polymers for use as membranes in three areas: 1) Electrolysis of water for ultra-pure hydrogen gas generation 2) Fuel cells applications for electricity generation, and 3) Desalination of water to provide drinking water. For each technology, a series of sulfonated poly(arylene ether sulfone) copolymers were synthesized and characterized. By applying different monomers or chemistries, a range of appropriate copolymers were synthesized whose characteristics varied in topology and architecture, depending on the desired application. Once these copolymers were synthesized, they were cast into membranes under proper established conditions. In addition, the structure-property-performance relationship of these sulfonated polysulfone membranes were further investigated to provide a direction for future studies.

No description available.

Effect of architecture at nanoscale on the macroscopic properties of polymer materials has long been a field of major interest, as evidenced by inhomogeneities in networks, multimodal network topologies, etc. The primary purpose of this research is to establish the architecture-property relationship of polymer networks by studying the physical and mechanical responses of a series of topologically different PTHF networks. Monodispersed allyl-terminated PTHF precursors were synthesized through ¡°living¡± cationic polymerization and functional end-capping. Model networks of various crosslink densities and inhomogeneities levels (unimodal, bimodal and clustered) were prepared by endlinking precursors via thiol-ene reaction. Thermal characteristics, i.e., glass transition, melting point, and heat of fusion, of model PTHF networks were investigated as functions of crosslink density and inhomogeneities, which showed different dependence on these two architectural parameters. Study of freezing point depression (FPD) of solvent confined in swollen networks indicated that the size of solvent microcrystals is comparable to the mesh size formed by intercrosslink chains depending on crosslink density and inhomogeneities. Relationship between crystal size and FPD provided a good reflection of the existing architecture facts in the networks. Mechanical responses of elastic chains to uniaxial strains were studied through SANS. Spatial inhomogeneities in bimodal and clustered networks gave rise to ¡°abnormal butterfly patterns¡±, which became more pronounced as elongation ratio increases. Radii of gyration of chains were analyzed at directions parallel and perpendicular to stretching axis. Dependence of Rg on ¦Ë was compared to three rubber elasticity models and the molecular deformation mechanisms for unimodal, bimodal and clustered networks were explored. The thesis focused its last part on the investigation of evolution of free volume distribution of linear polymer (PE) subjected to uniaxial strain at various temperatures using a combination of MD, hard sphere probe method and Voronoi tessellation. Combined effects of temperature and strain on free volume were studied and mechanism of formation of large and ellipsoidal free volume voids was explored.