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Xiong, Cher. "A study of two-component clear casting urethanes, urethane catalysts, and related processes." Online version, 1998. http://www.uwstout.edu/lib/thesis/1998/1998xiongc.pdf.
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Clayton, Anthony Brian. "Photopolymerised urethane acrylates /." Title page, contents and summary only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phc622.pdf.
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Alshuiref, Abubaker. "Synthesis and characterization of two novel urethane macromonomers and their methacrylic/urethane graft copolymers." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4022.
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Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: Polymethacrylates are well known adhesives and can carry specific functionality, but have the disadvantage that their flexible backbones impart limited thermal stability and mechanical strength. Polyurethanes (PUs) are finding increasing application and use in many industries due to their advantageous properties, such as a wide range of flexibility combined with toughness, high chemical resistance and excellent weatherability. PUs do however have some disadvantages, for instance, PU is considered an expensive polymer, especially when considered for solvent based adhesives. the focus of this study was to consider a largely unstudied area of PU chemistry, namely combining PUs with polymethacrylates. Two types of linear urethane macromers (UMs) UM1 and UM2 were synthesized by the polyaddition polymerization of 4,4'-methylenediphenyl diisocyanate (MDI) with ethylene glycol (EG), and MDI with neopentylglycol (NPG), via a pre-polymer method, followed by termination with 2-hydroxy ethylacrylate (2-HEA) and methanol (MeOH) to yield UMs having specific urethane chain lengths, and which have to be predominantly monofunctional. Structural identification of the UMs was verified by MALDI-TOF-MS, FTIR, 13C-NMR and 1HNMR spectroscopy.Various percentages of the respective UMs (0_55 wt % of methacrylate monomers) were then incorporated into polymethyl methacrylate (PMMA) and poly n-butyl methacrylate (PnBMA) backbones via solution free-radical copolymerization. The resulting methyl methacrylate-g-urethane and n-butyl methacrylate-g-urethane copolymers were characterized by 1H-NMR,13C-NMR, FTIR, SEC with double detectors (UV and RI), light scattering, UV-Vis, HPLC, TGA, DSC, DMA and TEM. Weight percentages of UM incorporated into the methyl methacrylate-g-urethane copolymers were calculated using FTIR, UV-Vis and 1H-NMR techniques. Phase separation which occurred between the urethane segment and methacrylate segment in the graft copolymerization products was investigated by DMA, DSC and TEM analysis. Microphase separation occurred in all PMMA-g-UM1 and PnBMA-g-UM1 copolymers: two glass transitions temperatures corresponding to the PMMA or PnBMA and UM1 fractions, respectively, were observed. On the other hand, DMA and DSC results showed that in most graft copolymer products the two respective component parts PMMA-g-UM2 or PnBMA-g- UM2 were compatible, because only one Tg was observed. Two glass transitions occurred for PMMA or PnBMA and UM2 when the amount of UM was increased to 55 wt % during copolymerization and microphase separation was evident in DSC, DMA and TEM measurements. Thermal stability and storage modulus (stiffness) of all the synthesized PMMA-g-urethane and PnBMA-g-urethane copolymers increased as the concentration of urethane macromonomer in the copolymerization feed increased, as confirmed in TGA and DMA results. The surface and adhesive properties of the synthesized graft copolymer were studied by measuring the static contact angle and peel strength. Adhesion increased as the content of UMs increased in the graft copolymer. The graft copolymers prepared using a high UM2 feed for both PMMA and PnBMA showed improved in adhesion compared to the pure methacrylate polymers. The adhesion was better for both leather and for vinyl.
AFRIKAANSE OPSOMMING: Polimetakrilate is bekende kleefstowwe. Hulle het egter die tekortkoming dat hulle buigbare ruggraat beperkte termiese en meganiese stabliteit besit. Poliuretane (PUs) word deesdae al hoe meer gebruik in baie nywerhede as gevolg van hulle baie voordele, insluitend hul wye buigsaamheid tesame met sterkte, hoë chemiese weerstand en uitstekende weerbaarheid. PUs het egter ’n paar nadele: hulle is baie duur, veral wanneer hulle gebruik word in oplosmiddel-gebaseerde kleefstowwe. Die doel van hierdie studie is om die kombinering van PUs met polimetakrilate te bestudeer, 'n onderwerp wat tot dusver baie min aandag-getrek het. Twee tipes liniêre uretaanmakromere (UMs), UM1 en UM2, is gesintetiseer deur gebruik te maak van poliaddisiepolimerisasie van 4,4'-metileendifeniel diisosianaat (MDI) met etileenglikol (EG), en MDI met neopentielglikol (NPG), via ‘n prepolimeermetode, gevolg deur terminering met 2-hidroksiëtielakrilaat (2-HEA) en metanol (MeOH). Die produk hiervan is UMs met spesifieke kettinglengtes (hoofsaaklik monofunksioneel). Die samestelling van die UMs is met behulp van die volgende gevorderde analitiese tegnieke bepaal: MALDI-TOFMS, FTIR, 13C-NMR en 1H-NMR. Verskillende hoeveelhede van die UMs (0_55 gewIing% metakrilaatmonomere) is dan in die polimetielmetakrilaat (PMMA) en poli-n-butielmetakrilaat (PnBMA) ruggrate geïnkorporeer deur middel van oplossing-vryradikaalpolimerisasie. Die samestelling van die kopolimeerprodukte, metiel-metakrilaat-g-uretaan en n-butiel-metakrilaat-g-uretaan, is met behulp van die volgende gevorderde analitiese tegnieke bepaal: 1H-NMR, 13C-NMR, FTIR, SEC met dubbele detektors (UV en RI), ligverstrooiing UV-Vis, HPLC, TGA, DSC, DMA en TEM. Die hoeveelheid UM geïnkorporeer in die metielmetakrilaat-g-uretaan kopolimere is bereken deur gebruik te maak van FTIR, UV-Vis en 1H-NMR data. Die faseskeiding wat plaasgevind het tussen die uretaansegment en die metakrilaatsegment in die produkte van die entpolimerisasie is met behulp van DMA, DSC en TEM ondersoek. In alle PMMA-g-UM1 en PnBMA-g-UM1 kopolimere het mikrofaseskeiding plaasgevind: twee verskillende glasoorgangstemperature vir die PMMA of PnBMA en UM1 fraksies is waargeneem. Hierteenoor het DMA en DSC resultate getoon dat in die meeste entkopolimeerprodukte (PMMA-g-UM2 of PnBMA-g-UM2) was die twee komponente verenigbaar, aangesien net een Tg waargeneem is. In die geval van die kopolimere waar die hoeveelheid UM in die kopolimerisasiereaksies tot 55 gew% verhoog is, is twee glasoorgangstemperature vir PMMA of PnBMA, en UM2 waargeneem. Mikrofaseskeiding is met behulp van DSC, DMA en TEM bewys. Termiese stabiliteit en stoormodulus (styfheid) van alle gesintetiseerde PMMA-g uretaan en PnBMA-g-uretaan kopolimere het toegeneem namate die uretaankonsentrasie in die kopolimerisasiereaksie toegeneem het soos deur middel van TGA en DMA resultate bewys is. Die oppervlakte- en kleefeienskappe van die bereide entkopolimere is bestudeer deur die statiese-kontakhoek en skilkrag te meet. Adhesie het toegeneem namate die UMinhoud toegeneem het. Die entkopolimere berei met hoë PMMA en PnBMA inhoud het uiteindelik beter adhesie getoon as die suiwer metakrilaatpolimere. Die adhesie was beter vir beide leer en viniel.
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Cobaj, Anisa. "The Effects of Urethane Methacrylates on the Film Properties of Acrylic-Urethane Hybrid Latexes." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1560335362557041.
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Kitson, Sean Leslie. "The mechanism of carcinogenesis by urethane." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242359.
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Zhang, Xiangcheng. "Fracture of modified urethane-methacrylate resins." Thesis, Cranfield University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358297.
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Van, Clack Ralph Vincent. "Non-isocyanate routes to urethane-polymers." Thesis, University of Central Lancashire, 2007. http://clok.uclan.ac.uk/20700/.
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The conventional synthetic route to urethane polymers involves the use of hazardous dflsocyanates which are synthesised using phosgene, the use of which produces a significant chlorine-waste stream. The processing of high molecular mass specialty polyurethanes regularly requires the use of organic solvents. This research aims to address these issues by separately employing enzyme-catalysis in order to synthesise high molecular mass polyurethanes and by investigating the use of high pressure CO2 as an alternative to the use of organic solvents in the synthesis of urethane polymers. The main building blocks in the enzyme-catalysed synthesis of urethane polymers are based on di-functional carbamate-blocks, synthesised by reaction of diamines with ethylenecarbonate or dimethylcarbonate. In addition to the more conventional di-functional carbamate-blocks, the synthesis of a novel mono-carbamate based on an amino acid has been investigated. The mechanism of the polymerization of adipic acid and hexane diol was investigated. The reaction was optimised for the high vacuum reaction in bulk and solution, as well as for the polymerisation under Dean-Stark distillation conditions. Although the dimethylcarbonate-based carbamate-compounds proved to be too resistant against enzymatic cleavage, the enzyme-catalysed co-polymerisation of ethylene-based carbamate-blocks with adipic acid and hexane diol eventually led to the synthesis of high molecular mass segmented urethane polymers in excess of 30000 g moi1. The crystallisation behaviour of both enzyme-catalysed polyesters and polyurethanes has been investigated and the differences in crystallisation for the polyesters have been shown to be caused by the presence of small quantities of residual enzyme. The enzyme appears to act as a nucleating agent for the crystallisation and increases the uniformity of crystallisation and the rate at which a crystalline structure was obtained upon cooling. The thermal properties of the enzyme-catalysed polyurethanes have been determined and compared to conventional polymers. Although the molecular mass of the enzyme-catalysed urethane polymers are comparable to those obtained via the conventional route, it has not been possible to reproduce their physical p rope rties. The use of high pressure CO2 to eliminate the need of a solvent in the synthesis of a urethane polymer was studied. The use of a pressure of 4.5 bar 002 has been shown to enhance the reaction rate for this reaction procedure. GPC analysis confirmed that polyurethanes with a molecular mass of approximately 53000 g moi1 were synthesised in 200 minutes, whereas the same reaction under atmospheric conditions required a longer reaction time (260 minutes) before the same molecular mass polyurethane was obtained.
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Degrandi, Elise. "LATEX HYBRIDES URETHANE/ACRYLIQUE POUR APPLICATIONS ADHESIVES." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00465348.
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Cette thèse a pour objet l'étude de films adhésifs obtenus par le séchage de particules de latex hybrides uréthane/acrylique. Ces latex ont été préparés par polymérisation en miniémulsion pour assurer une incorporation homogène du polyuréthane dans chaque particule. L'étude de la morphologie des particules et des films a montré que le greffage du polyuréthane sur le réseau acrylique est essentiel pour éviter une séparation de phase à l'échelle du film, néfaste pour les propriétés macroscopiques. Les propriétés mécaniques de ces films hybrides sont contrôlés par deux paramètres indépendants : La fraction massique de polyuréthane affecte la viscoélasticité linéaire de ces films adhésifs alors que le taux de greffage du polyuréthane modifie le comportement en grandes déformations en modifiant la maille du réseau réticulé. En modifiant le taux de greffage, il est possible de maintenir un niveau d'adhérence satisfaisant par rapport à un film d'acrylique pur tout en augmentant la cohésion dans le matériau et donc la résistance au cisaillement. Cette méthode de synthèse par miniémulsion peut être transposée vers un processus plus industriel et l'effet des paramètres moléculaires reste globalement le même. L'effet du greffage apparaît toujours comme essentiel sur la déformabilité maximale des films adhésifs mais les conditions de synthèse augmentent fortement la densité de points de réticulation dans le matériau, ce qui diminue leur adhérence mais augmente leur résistance au cisaillement. Nous avons enfin mis au point un test de fluage en traction, permettant d'appréhender la résistance mécanique des adhésifs dans le temps.
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Wu, Yong Kang. "Biostability/biodegradation of poly(ether urethane)s." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1061314415.
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Todd, Jordana Louise. "UV-initiated synthesis of novel urethane polymers." Thesis, University of Central Lancashire, 2007. http://clok.uclan.ac.uk/20200/.
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The Barton reaction involves the photoinitiated rearrangement of nitrite esters and is used primarily in the synthesis of complex steroidal structures. The rearrangement results in the introduction of active hydrogen atoms into the molecule and a novel use of this reaction for the production of polyurethane coatings through a photopolymerisation reaction with isocyanates has been discovered. The nitrite esters were synthesised from nitrous acid produced in situ from sodium nitrite and sulfuric or nitric acid. Yields of 79.5 and 76.4% were obtained in the synthesis of the mononitrite esters butyl- and hexyl-nitrite, however lower yields of 55.1 and 53.4% were obtained in the synthesis of butane-1,4- and hexane-1,6-dinitrite respectively. It was found that the nitrite esters are very rapidly hydrolysed and loss of product through hydrolysis occurs during the synthesis because of the aqueous environment in which it is carried out therefore a position of equilibrium is reached. The kinetics of the hydrolysis reaction was studied by monitoring the change in pH over time for both butyl- and butane-I,4-di-nitrite. The sensitivity of the nitrite esters to hydrolysis not only makes the synthesis of nitrite esters problematic but it also means that storage above the critical pH of 6.8 and at a temperature of 2-8°C is crucial to maximise the storage stability of the samples. The stability of the nitrite esters mixed with isocyanates was determined, the results indicated that the two reagents did not react and therefore the compounds could be stored together prior to irradiation. An extensive study on the reactions occurring after the photolysis of a series of nitrite esters was undertaken. The optimum wavelength range of 3 10-385 nm was confirmed for the occunence of the Barton reaction and results showed that the competing reaction of disproportionation also occurred after irradiation. The structure of the starting nitrite was found to have a significant effect on the reactions occurring after photolysis. A chain length of greater than 4 carbon atoms was found necessary for the Barton reaction to dominate over disproportionation because the intramolecular hydrogen abstraction 111 step involved a secondary hydrogen atom, whereas when a nitrite ester with only a 4 carbon chain was subjected to photolysis the disproportionation reaction was the dominant reaction because a primary hydrogen atom was abstracted. However this trend was not observed during the photolysis of dinitrite esters, the Barton reaction occurred to a greater extent than the disproportionation reaction even when a primary hydrogen atom was abstracted due to the second nitrite group which facilitates its removal. A series of coatings were produced from solutions of nitrite esters and isocyanates. It was found that a catalyst was essential to drive the reaction towards the Barton reaction and prevent the occurrence of the disproportionation reaction in order to ensure the formation of highly cured coatings. An excess of nitrite was required to compensate for the loss of nitrite ester through evaporation that prevented the production of highly cured coatings. The occurrence of a post-curing reaction was observed due to the continuation of the reaction of the isocyanate with residual active hydrogen compounds. The film thickness, nitrite ester, isocyanate and catalyst used were all found to have an effect on the rate of the polymerisation reaction. The photolysis reaction was also affected by the conditions under which the photopolymerisation reaction was undertaken. In a heated system an oxime compound was formed after photolysis whereas when a cooled curing oven was used a dimer was produced. The formation of the dimer also resulted in coatings with inferior properties; this is because the absence of oxime groups and the lower temperature reduces the rate of the polymerisation reaction resulting in increased formation of by-products. The properties of the coatings produced were tested and were found to have good solvent resistance (over 100 MEK double rubs), pencil hardness (7H), resistance to deformation (3mm pass in the bend test), adhesion (cross-cut value of 0) and weathering resistance. The properties of the coatings were also comparable to standard coatings indicating that they may have commercial importance.
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Hunt, Jason Patrick. "Synthesis and dynamic mechanical studies of a urethane-based polyrotaxane." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/8553.
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Alshuiref, Abubaker. "Synthesis and characterization of urethane-acrylate graft copolymers." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/491.
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Christenson, Elizabeth. "Biostability and Biocompatibility of Modified Polyurethane Elastomers." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1118268387.
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Abd, Elrehim Mona Hassan Mohammed. "Synthesis and characterization of hyperbranched poly(urea-urethane)s." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1091096011203-44194.
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The thesis aims to synthesize hyperbranched poly(urea-urethane) polymers (HPU) in one-pot method using commercially available monomers which are 2,4-toluylene diisocyanate (TDI) as aromatic diisocyanate and isophorone diisocyanate (IPDI) and 2(3-isocyanatopropyl) cyclohexylisocyanate (IPCI) as aliphatic diisocyanates. Those proposed diisocyanates were reacted with diethanolamine (DEA) or diisopropanolamine (DIPA). Conditions of polymerisation reactions were optimised. Complete structural analysis using 1H and 13C NMR for the obtained aromatic polymers was carried out. Degree of branching up to 70% was calculated. Aliphatic polymers have spectra with overlapped signals therefore, no full structural analysis was possible. Molar masses were determined using SEC/RI detector which shows that the prepared polymers have Mw values between 1600 g/mol and 106000 g/mol. Thermal analysis for different polymer systems showed that aliphatic HPU are more thermally stable and have values of glass transition temperature higher than aromatic ones. Modification of the end groups in the prepared hyperbranched polymers was carried out using three different modifiers and degree of modification up to 100%. Linear polymers based on the same diisocyanate monomers were prepared to compare the properties of hyperbranched systems with their linear analogs. Measurements of solution viscosity showed that HPU have lower solution viscosity values than their linear analogs of comparable molar masses. Rheological measurement of some polymer samples of different systems were carried out and showed that our hyperbranched systems exhibit a more elastic behavior than the linear polymers. Surface studies for thin films prepared from different polymer systems (hyperbranched, linear and modified) were carried out and the obtained thin films were characterized using light microscope, microglider, GC-MS, and AFM. Contact angle measurements showed that HPU have a relatively hydrophilic character. The modified polymers have higher contact angle values than the unmodified ones due to the lack of OH end groups. Networks based on aliphatic and aromatic HPU were prepared through the reaction of HPU with trimer of 1,6-diisocyanatohexane and characterised by DSC, GC-MS, DMA and AFM. The domain size in aromatic networks was found to be larger than in aliphatic networks. Tensile test was carried out and it was found that aliphatic network is more elastic than aromatic one.
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Kiziltay, Aysel. "Biodegradable Poly(ester-urethane) Scaffolds For Bone Tissue Engineering." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613811/index.pdf.
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During last decade, polyurethanes (PUs) which are able to degrade into harmless molecules upon implantation have received a significant level of attention as a biomaterial in tissue engineering applications. Many studies are focused especially on development of PUs based on amino acid derivativeshowever, there are only few applications of amino acid based PUs in tissue engineering. In this study, a biocompatible and biodegradable thermoplastic poly(ester-urethane) (PEU) based on L-lysine diisocyanate (LDI) and polycaprolactone diol (PCL) was synthesized and used for the preparation of two dimensional (2D) films and three dimensional (3D) scaffolds. The resulting polymer was casted as 2D films for full characterization purpose and it was found that it is highly elastic with modulus of elasticity ~12 MPa. Surfaces of 2Ds were modified via micropatterning and fibrinogen coating to check the material-cell interaction. The 3D scaffolds were obtained by salt leaching and rapid prototyping (bioplotting) techniques. The 3D scaffolds had various pore size and porosity with different mechanical strength. The bioplotted scaffolds had uniform pore size of ~450 µ
m and exhibited higher compressive modulus (~4.7 MPa) compared to those obtained by salt leaching (~147 kPa). Salt leached 3D scaffolds had inhomogenous pore size distribution in the range of 5 µ
m - 350 µ
m and demonstrated greatest degradation profile compared to 2D films and 3D bioplotted samples under enzymatic condition. Rat bone marrow stem cells (BMSCs) were used to investigate the biocompatibility of the polymer and suitability of fabricated scaffolds for osteogenesis. Presence of micropatterns on 2D matrices did not show any influence on osteoblastic function, but presence of fibrinogen enhanced cell attachment and proliferation. All of the fabricated 3D PEU matrices supported proliferation, osteoblastic differentiation and extracellular matrix (ECM) deposition with highest osteoblastic activity on bioplotted scaffolds which confirmed by von Kossa staining and EDX analysis. The results indicated that the synthesized PEU based scaffolds were able to induce osteoblastic differentiation and mineralization of BMSC and therefore these scaffolds can be good candidates to be used in bone tissue engineering
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Preston, Christopher M. L. "Poly(dimethylsiloxane) : blends with poly(urethane) & radiation chemistry /." [St. Lucia, Qld.], 2000. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16169.pdf.
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Hsu, Tze-Chien Jeffrey. "Urethane-based IPNs and polyureas in reactive polymer processing /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487331541711679.
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Lau, Soo-Khim. "The structure-property relationships of urethane-acrylic thermosetting systems." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/27415.
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Urethane-acrylic copolymers have found increasing use as a radiation curable materials in the recent years. These copolymers are highly crosslinked through the use of acrylic monomers having more than one double bond. Stirling Lloyd had discovered such materials to be a successful alternative to the urethane or acrylics coatings as waterproof membrane coatings. In this project, structure-property relationships of UA copolymer systems were studied. These were peroxide cured at room temperature.
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Wintersgill, S. "Reactions of group IV metal compounds with isocyanates, and their catalytic applications." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311171.
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Gibb, Jack Nicholas. "The competing reactions of polyurethane foam formation : a computational and experimental study." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648568.
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Fallon, Jake Jeffrey. "Structure-Process-Property Relationships of Cellulose Nanocrystal Thermoplastic Urethane Composites." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/103053.
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Nanomaterials are becoming increasingly prevalent in final use products as we continue to improve our understanding of their structure and properties and optimize their processing. The useful applications for these materials extend from new drug delivery systems to improved materials for various transport industries and many more. Nanoscale materials which are commonly used include but are not limited to carbon nanotubes, graphene, silica, nanoclays, and cellulose nanocrystals. The literature presented herein aims to investigate structure-process-property relationships of cellulose nanocrystal (CNC) polymer composites. These CNC nanocomposites are unique in that they provide a dynamic mechanical response when exposed to H2O. Currently, these nanocomposite systems are most commonly solvent cast into their final geometry. In order to enable the use of these materials in more commercial processing methods such as extrusion, we must understand their inherent structure-process-property relationships. To do this, we first characterize the influence of temperature and shear orientation on the unique mechanical adaptive response. Next, the melt processability of the nanocomposite was characterized using material extrusion (MatEx) additive manufacturing (AM). Additionally, the diffusion behavior of water within the film, which controls the dynamic mechanical response, was probed to better predict the concentration dependent behavior. Finally, a literature review is presented which outlines the state of the art for melt extrusion AM of fiber filled polymer composite materials and provides insight into how we can further improve mechanical properties through further addition of composite filler materials.
The initial focus of the dissertation is on the influence of melt processing CNC thermoplastic urethane (TPU) composites and the resulting impact on the mechanical adaptive response. Dynamic mechanical analysis (DMA) fitted with a submersion clamp was used to measure the mechanical softening of the composite while submerged in water. Small angle x-ray scattering (SAXS) and polarized raman spectroscopy were used to qualify the orientation of the various CNC/TPU composite samples. The results of the orientation measurements show that solvent casting the films orient CNCs into a mostly random state and melt extrusion induces some degree of uniaxial orientation. The DMA results indicate that at the processing conditions tested, the uniaxial orientation and thermal exposure from the melt processing do not significantly impact the mechanical responsiveness of the material.
The next objective of this work was to expand upon the aforementioned learnings and determine the CNC composite material processability using MatEx. The ability to process mechanically dynamic CNC/TPU composites with a selective deposition process capable of generating complex geometries may enable new functionality and design freedom. To realize this potential, a two factor (extrusion temperature and extrusion speed) three level (240, 250 and 260 ℃/ 600, 1100 and 1600 mm/min) design of experiments (DOE) was utilized. The resulting printed parts were characterized by DMA to determine their respective mechanical adaptivity. Processing conditions did prove to have a significant impact on the mechanical adaptivity of the printed part. A correlation between applied energy and mechanical adaptivity demonstrates how increasing residence time and temperature can reduce mechanical performance. The shape fixity of the printed parts was calculated to be 80.4% and shape recovery was 44.2%. A 3D prototype part was also produced to demonstrate the unique properties of this material.
Although the understanding of the melt processing behavior of these CNC composites had been improved, a stronger understanding of the moisture diffusion behavior within the composite is required to fully realize and control their potential. Therefore, a study was undertaken to capture the diffusion behavior and correlate it to the mechanical responsive mechanism. To do this, a thermogravimetric sorption analysis (TGA-SA) instrument was used to monitor the mass uptake as a function of time exposed to a humid environment. These data were then compared to DMA data collected for the same samples exposed to a similar degree of humidity. All studies were conducted as a function of concentration in order to better elucidate the influence that percolating network structures may have on the resultant properties. Interestingly, the results show how increasing addition of CNCs results in a decrease in the rate of diffusivity, which is counter to what has been commonly hypothesized. It is hypothesized that increasing CNC content restricts the mobility of surrounding amorphous matrix material, thus increasing the resistance for diffusion of a water molecule. However, the rate of mechanical adaptation was found to increase with increasing CNC content, which is believed to be a result of the increased connectivity, enabling further transport of water molecules.Doctor of Philosophy
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Bakhshi, R. "Coating stent materials with polyhedral oligomeric silsesquioxane-poly(carbonateurea)urethane nanocomposites." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/18987/.
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The long-term efficacy of coronary or peripheral stenting is limited by in-stent restenosis (ISR), which occurs in 15 to 30% of patients and is attributed primarily to neointimal hyperplasia. By adding a drug-eluting coating, this rate has been reduced to about 5% or less. However, recently longer-term follow-up data has highlighted problems with drug-coated stents, including late stage thrombosis. A bio-stable poly(carbonate-urea)urethane has been used for stent coating and the surface properties of the polymer have been optimised by incorporating the polyhedral oligomeric silsesquioxane molecule. These POSS polymers improve the adhesion and the growth of endothelial cells. The work described in this thesis, presents an innovative approach in self-expanding/balloon expandable coronary stent design that incorporates a NiTi/stainless steel alloy scaffold with a polyhedral oligomeric silsesquioxane- poly (carbonate-urea) urethane nanocomposite polymer (POSS-PCU) coating. Electrohydrodynamic spraying and ultrasonic atomization spraying of the non-biodegradable nanocomposite polyhedral oligomeric silsesquioxane (POSS) polymer have been investigated in detail for coating metallic stent materials and compared with dip coating. Because of the tight geometry of coronary stents, these new coating techniques have been shown to offer advantages over traditional coating techniques. These advantages include, reduced polymer consumption, precise coating thickness as low as 10 μm and a highly controllable spray which leads to consistent reproducible results. However, poor adhesion, or bond deterioration over the lifespan/ deployment of the device could reduces the efficiency and could impart even more complexity to the implant including formation of debris which can induce thrombus formation. Changing the surface physical property/chemical composition through the proposed protocol has been shown to increase the bonding strength by up to three times. This study has identified a new process and conditions which can be used in stent coating research.
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Hullard, Stephen Mark. "Studies towards siloxane-urethane elastomers for upper extremity prosthesis cosmetic gloves." Thesis, Cardiff University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316357.
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Anderson, Gabriel Donn. "Long-term Durability Characterization and Prediction of a Urethane-based Adhesive." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/98825.
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Polymeric adhesives play an increasingly critical role in today's engineering designs. When used, adhesively bonded components reduce or eliminate the need for bolted or welded connections. In many cases, this can reduce stress concentrations and weight. With energy dissipating adhesives, noise and vibration reduction are possible, as is the use of unique or complicated designs that could not otherwise be constructed. Adhesive properties however, can vary greatly with time, temperature, and environmental exposure conditions such as moisture. It is therefore critical, to understand the behavior of adhesives over the range of conditions that a bonded component might experience. In this work, the behavior of a urethane-based adhesive was characterized and long-term durability predictions were developed as a result of the data collected.
The popular T-peel sample geometry has been used extensively in this study to explore the mechanics of a bonded system and the resulting impact on adhesive durability. The T-peel specimens used, consist of two aluminum sheets or adherends bonded together, with tabs bent back in the shape of a "T" for gripping in a universal load frame. Unlike some other test geometries, T-peel samples are often made with relatively thin adherends that may experience significant plastic deformation during testing. This extraneous energy dissipation greatly complicates the analysis to extract meaningful fracture properties of the adhesive. During testing, the load required to propagate a crack in the adhesive layer is measured at fixed displacement rates. The total system energy can then be partitioned into the energy dissipated within the adhesive (fracture energy), and the energy dissipated through plastic work in bending of the adherends. By performing these tests at different temperatures and rates, the calculated fracture energies span a wide range of possible material behavior. Using the principles of Time Temperature Superposition (TTS), the collected data can be shifted to different times or temperatures. This behavior is well understood in polymer physics, and is made possible with material specific "shift factors". By using the principles of TTS, data collected in in a relatively short experimental window, can be used to accurately predict the behavior of the adhesive in years or even decades.
In this work, nearly 200 T-peel samples were tested in four different studies. A preliminary set of unaged specimens was used to develop testing and data analysis methodologies. A second set of unaged samples was tested over a wide range of temperatures and rates, in addition to a third group, subjected to constant moisture and cyclically varying temperature. The final set of specimens, was exposed to 20 separate isothermal aging conditions. The experimental data showed that the 400+ cycles, were insufficient to statistically distinguish these samples from their unaged counterparts. Additionally, samples aged for up to 2000 hours in a dry environment, or 500 hours in a wet environment, showed no reduction in fracture energies in comparison with unaged samples. Specimens aged for more than 500 hours however, were observed to have a significant decrease in fracture energy values.
Strong correlations between the thickness of the adhesive layer and estimated fracture energy values were found in this study. As adhesive thickness varied substantially due to manufacturing differences in the specimens tested, new analysis techniques were developed to deal with the variations in adhesive thickness. A MATLAB code based on the ICPeel program, was written to provide a spatial variation of parameters such as adhesive thickness, peel load, and fracture energy. This provided additional insights into the behavior of these T-peel coupons, and prompted the investigation of the Universal Peel Diagram concept. While this diagram was not found to be applicable to the adhesive tested in this study, the analysis indicated that T-peel coupons could be multivalued. That is, a single measured load value does not always describe an adhesive's fracture energy (as is widely believed). Depending on the sample's geometry and material properties, several measured loads could cause debonding. This has potentially far reaching implications on the selection of appropriate T-peel test geometries, as a single measured load is often assumed to correlate to an adhesive's true fracture energy.
In this work, both aged and unaged T-peel specimens were tested and the basis of the Universal Peel Diagram investigated. Given sufficient exposure times to moisture, elevated temperatures were found to significantly reduce the amount of energy dissipated in the urethane-based adhesive. Additionally, the Universal Peel Diagram indicated that for some systems, the load required for debond is in fact, multivalued. Therefore, care should be taken when designing a T-peel test configuration to avoid the multivalued regions.Master of Science
Polymeric adhesives play an increasingly critical role in today's engineering designs. When used, adhesively bonded components reduce or eliminate the need for bolted or welded connections, reducing their weight in the process. With adhesives, noise and vibration reduction are possible, as is the use of unique or complicated designs that could not otherwise be constructed. Adhesive properties, however, can vary greatly with time, temperature, and other environmental exposure conditions such as moisture. It is therefore critical to understand the behavior of adhesives over the range of conditions that a bonded component might experience. In this work, the behavior of a urethane-based adhesive was characterized in order to develop long-term durability predictions. Numerous test methods have been developed to characterize the behavior of adhesively bonded joints. In this work, T-peel specimens were used consisting of two aluminum sheets (the adherends), bonded together with tabs bent back in the shape of a "T" for gripping in a universal load frame. During testing, the load required to propagate a crack in the adhesive layer is measured. An outcome of this measurement and subsequent data analysis is the fracture energy—a measure of the effectiveness of the adhesive in transferring loads. If we perform these tests at different temperatures and loading rates, we can determine fracture energy values which span a wide range of possible material behavior. Using principles from basic polymer physics, the collected data can be shifted to different times or temperatures enabling us to accurately predict the behavior of the adhesive over years or even decades. In this work, nearly 200 T-peel samples were tested in four different studies. A preliminary set of unaged specimens was used to develop testing and data analysis methodologies. Unaged and cyclically (temperature) aged samples were tested over a wide range of temperatures and rates. The fourth set of specimens was subjected to 20 separate isothermal aging conditions and also tested at different temperatures and rates. The experimental data showed that the 400+ temperature cycles were insufficient to damage these samples significantly. Additionally, samples aged for up to 2000 hours in a dry environment, or 500 hours in a wet environment showed no reduction in performance in comparison with unaged samples. Specimens aged for more than 500 hours in a wet environment however, demonstrated a significant decreases in fracture energy values. Strong correlations between the thickness of the adhesive layer and estimated fracture energy values were found in this study, and new analysis techniques were developed to analyze the effect of these thickness variations on the joint performance.
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Klepáč, Patrik. "Výroba mělkého výtažku pryží." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228146.
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An object of this master thesis is the proposal of variants solving a manufacturing of required part and the selection right technology for single part production of required part from stainless steel 17240 (DIN 1.4301). At the first part of this thesis is briefly reviewed conventional forming and at rest of this thesis is closely reviewed the technology using the elastic tools (rubber, urethane), hydroforming technology and design of proper tool for required part. At the end of this work will be release economics estimation of fine technology and designed tool.
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Bass, Roger Wesley. "Synthesis and Characterization of Self-Healing Poly (Carbonate Urethane) Carbon-Nanotube Composites." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/2999.
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Synthesis of high molar mass polycarbonate polyurethanes using a novel polyol is described. The resulting elastomers demonstrate excellent mechanical properties as well as the capability to re-heal after rupture without the addition of additives or imbedded healing agents. The self-healing functionality is shown to greatly improve with the addition of up to 1% single and multi-walled carbon nanotubes. The interface of the carbon nanotubes and self-healing polymer are probed using Raman techniques and provide an insight into how the self-healing actions are improved with the addition of carbon nanotubes.
Synthesis of polycarbonate polyurethanes and carbon nanotube composites using a novel casting method is described and compared to the more traditional solution casting method. The dispersion of the carbon nanotubes is evaluated as well as the effect of effective dispersion on the composites through tensile testing, rheometry and hardness testing. Although complete agglomeration avoidance could not be achieved, significant size decrease was observed. Over 200% improvement in tensile strength is shown with conventional solution casting method which is further improved by the described novel solution casting method.
Contact angle measurements on our novel self-healing poly (carbonate urethane) and CNTs composites show that surface energies are drastically changed when CNTs are used. The most revealing finding is that f×svp increases in CNT composite materials from ~30% of the surface energy on average for the samples tested, to ~80%. We have shown that surface free energies increase most likely as a result of exposing hydrogen bonding sites typically found within the bulk in polyurethanes. Our polyurethane differs from traditional polyurethanes in that it has both novel soft segments made from a novel polycarbonate polyol discussed in chapter 2 and relatively soft ¡§hard¡¦ segments resulting from the use of H12MDI, all leading to increased ability to hydrogen bond within the material. The availability of the hydrogen bonding sites is demonstrated by FTIR absorbance bands for associated and unassociated hydrogen bonding sites, which do not seem to be accessible to a large until the PCPU¡¦s surface is disrupted. Once disrupted, the exposed hydrogen bonding sites are able to bond with other bonding sites of adjacent ruptured surfaces. This would explain why our material is non-blocking, e.g. won¡¦t stick to itself, until the surface is ruptured. It would also explain why any two ruptured surfaces of our material will reheal, even if they were not attached previously.
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Tipton, Allison Breanne. "An investigation into the imaging properties of semi-rigid urethane casting resin." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/1271.
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Imagemaking is a universal impulse experienced by all human cultures. In the continual pursuit to create compelling and engaging forms, efforts to permit images to interact in dynamic ways in extended space have been the subject of considerable exploration. The often sought-after goal is to break the surface of the paper without sacrificing the essence of the image. My current research is the investigation of Smooth-On 300 series Semi-Rigid Urethane Casting Resin and its interaction with various laser jet inks on diverse paper or paper analogous mediums. Purely on accident, it was discovered that one could easily transfer printed images onto the casting resin if it was poured directly on the print. This has allowed for a method of image manipulation in a manner that has yet to be thoroughly explored. Several experimental pours and projects have been completed to test the limits and potentiality of this new media. The results seem promising and warrant farther exploration of this exciting new development.
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Meng, Lei. "Investigation of non-isocyanate urethane functional latexes and carbon nanofiller/epoxy coatings." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1445733724.
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QUINI, JOSUE G. "Adesivos estruturais uretânicos aplicados a combinações de compósitos plásticos e metais." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9995.
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Made available in DSpace on 2014-10-09T12:33:38Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:04:04Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Barnes, Dunstan Henry. "Calcium phosphate coatings on polycarbonate urethane substrates for artificial spinal disc replacement devices." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608917.
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O'Sickey, Matthew J. "Characterization of Structure-Property Relationships of Poly(urethane-urea)s for Fiber Applications." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/26792.
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Poly(urethane)s and poly(urethane-urea)s (PUU) are nearly ubiquitous, having been in existence since before the Second World War. Spandex, a poly(urethane-urea) elastomeric fiber, is found in nearly all articles of apparel as well as in an increasing array of other consumer items. The technology and chemistry of spandex is largely unchanged since its inception in the late 1950s, with the majority of spandex employing poly(tetramethylene ether glycol) as soft segments. Recent developments in catalyst technology have resulted in the production of ultra-low monol content poly(propylene glycol) (PPG), which is nearly difunctional (f=1.95+). This enhancement in difunctionality has potentially enabled the use of PPG as a spandex soft segment with potential spandex processing, performance, and economic benefits.
PPG-based spandex elastomers were evaluated in both film and fiber form for the purpose of investigating morphological, orientational, mechanical, and thermal properties with the goal of understanding relationships between chemistry, morphology and properties. Key variables of interest were soft segment molecular weight (MW), molecular weight distribution (MWD), and composition, and hard segment content and composition. Of those, the influence of the molecular weight distribution of the polyol used for soft segments was of foremost interest and had previously been largely neglected during the course of poly(urethane) and poly(urethane-urea) research.
It was found that over the range of PUU compositions suitable for production of spandex, that hard segment content and composition had little effect upon the morphology and thermal and mechanical properties. Appreciable trends as functions of soft segment molecular weight were observed. The soft segment MWD was adjusted through the addition of a low molecular weight homolog of PPG, tri(propylene glycol) (TPG), decreasing the number average soft segment MW. The results of these experiments were contrary to those for variation of soft segment molecular weight. It was determined that the low MW portion of the polyol MWD contributes to the building of hard segments in addition to or in lieu of soft segments.
Incorporation of TPG in the PUUs resulted in larger, presumably less cohesive, hard domains and increased hard segment content. The TPG containing materials had enhanced tensile properties, less permanent set, and less residual orientation after deformation. These materials proved quite comparable to those using PTMEG soft segments.
Comparison of film and fiber PUUs revealed only minor differences, implying that the trends and conclusions drawn from the study of films with spandex-like compositions would also hold for fibers. The key difference between films and fibers is that fibers maintain some residual ordering and orientation due to drawing of the fibers during processing. Of the processing variables investigated, none impacted the morphology as determined from small angle x-ray scattering.
It was concluded, that of the various compositional variables germane to spandex, the polyol MW and MWD played key roles in development of morphology, and hence properties. The role of polyol MWD had been woefully neglected during the development of spandex previously, and was observed to be a critical variable.Ph. D.
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Asplund, Basse. "Biodegradable Thermoplastic Elastomers." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7434.
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Nebipasagil, Ali. "Chemically and Photochemically Crosslinked Networks and Acid-Functionalized Mwcnt Composites." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/42703.
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PTMO-urethane and urea diacrylates (UtDA, UrDA) were synthesized from a two-step reactions of bis (4-isocyanatocyclohexyl) methane (HMDI) with either α,Ï -hydroxy-terminated poly (tetramethylene oxide) (PTMO Mn 250, 1000, 2000 and 2900 g/mol) or α,Ï -aminopropyl-terminated PTMO and 2-hydroxyethyl acrylate (HEA). PTMO-based ester precursors (EtDA) were also synthesized from α,Ï -hydroxy-terminated PTMO (Mn 1000 and 2000 g/mol). Two bis acetoacetates were synthesized from acetoacetylation of 1,4-butanediol and 250 g/mol hydroxy-terminated PTMO with tert-butyl acetoacetate. 1H NMR spectroscopy confirmed the structure and average molecular weights (Mn)of diacrylates. Mn of these precursors were in the range of 950 to 3670 g/mol by 1H NMR. The rheological properties of diacrylates were studied and activation energies for flow were calculated. Activation energies increased with increasing Mn and hydrogen-bond segment content. Michael carbon addition was employed to covalently crosslink the precursors resulting in networks with gel fractions better than 90%. DSC and DMA experiments revealed that networks had a broad distribution of glass transition temperatures depending on Mn and degree of hydrogen bonding present in the diacrylates. Their Tgâ s varied from -61 ºC to 63 ºC depending on the crosslinking density and hydrogen-bonding segment content. TGA revealed that UtDA and UrDA networks had an improved thermal stability compared to their EtDA counterparts. Tensile properties showed a variation depending on the structure and Mn of diacrylate and BisAcAc precursors. The storage moduli of networks precursor change from 25.3 MPa to 2.0 MPa with increasing Mn of the urethane diacrylate Elongation at break increased from 255% to 755 % for the same networks. The Youngâ s moduli increased from 3.27 MPa for EtDA 2000 to 311.1 MPa for UrDA 2000 which was attributed to increasing degree of hydrogen-bonding.
Acid functionalization of C70 P Baytubes multiwalled carbon nanotubes (MWCNT) generated acid-functionalized nanotubes (MWCNT-COOH). Suspension of MWCNT-COOH in organic solvents (chloroform, toluene, THF, DMF and 2-propanol) were prepared. DLS indicated average particle diameters of MWCNT-COOH in DMF and in 2-propanol were 139 nm and 162 nm respectively. FESEM of suspensions revealed aggregate free dispersion of MWCNT-COOH in DMF and 2-propanol. MWCNT-COOH containing composite networks were prepared. FESEM images of fracture surfaces of UtDA showed MWCNT-COOH were well-dispersed in the composites. DMA showed an increase in the rubbery plateau modulus which correlated with the MWCNT-COOH content in the networks. Tensile testing also revealed a relationship between MWCNT-COOH content and youngâ s moduli and strain at break of networks. Storage moduli of networks increased from 25 MPa to 211 MPa with increasing MWCNT-COOH content whereas elongation at break decreased from 255 % to 146 %.
UtDAs and pentaerythritol tetraacrylate (PETA) were crosslinked under UV radiation (6 passes, 1.42 ± 0.05 W.cm2 for each pass) in the presence of 2,2-dimethoxy-2-phenylacetophenone (DMPA) (1 wt. % of the mixture) UV initiator. DMA demonstrated the presence of broad glass transition regions with a range of Tgâ s which varied from -60 °C to -30°C. Tensile testing also revealed the relationship between Youngâ s moduli, strain at break and the molecular weight of the diacrylates. The increasing molecular weight of urethane diacrylate precursors caused a drop in the storage moduli of networks from 15.8 MPa to 1.4 MPa and an increase in elongation at break from 76 % to 132 %.Master of Science
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Cornish, Martyn Christopher. "Role of chemical architecture on the physical properties of model poly(urethane-urea) elastomers." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705546.
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BOHN, VERONIQUE. "Contribution a l'etude du carbamate d'ethyle (urethane) dans les eaux de vie de fruits." Strasbourg 1, 1987. http://www.theses.fr/1987STR10771.
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Nishioka, Marcia G. "Identification of Carcinogenic Di-amines in the Indoor Environment from Common Urethane Polymer Products." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu148344608670484.
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Borth, David J. "Non-Destructive Evaluation of Urethane-Ester Coating Systems Using the Scanning Kelvin Probe Technique." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1524749968517527.
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Sasubilli, Ramakrishna Gutheil William G. "Solid-phase synthesis of peptides and peptide mimetics using urethane and backbone amide linker strategies." Diss., UMK access, 2006.
Find full textAbstract:
Thesis (M.S.)--School of Pharmacy. University of Missouri--Kansas City, 2006."A thesis in pharmaceutical sciences." Typescript. Advisor: William G. Gutheil. Vita. Title from "catalog record" of the print edition Description based on contents viewed Nov. 9, 2007. Includes bibliographical references (leaves 63-73). Online version of the print edition.
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Carpenter, Phillip P. "Examination of the surface and interfacial properties of an epoxide-urethane resin for surface coatings." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/32637.
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Electrodepositable paints are used in the auto industry to provide the majority of the protection against corrosion to mild steel car body shells. They are generally epoxy/blocked isocyanate resins systems which are applied by action of an electropotential between the car and an anode. Upon heating to 175°C the blocked isocyanate deblocks, and crosslinking occurs predominantly via the formation of urethane and urea linkages. The aim of the project was to gain a better understanding of the factors which may affect the adhesion of the electrocoat resin polymer to a steel surface, to investigate possible replacements for the tin catalyst currently used, and to develop a quantitative mechanical test for paint adhesion. This was achieved by employing various analytical techniques including Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and mechanical testing.
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Iurzhenko, Maksym. "Electrical, thermomechanical and sorption properties of hybrid organic-inorganic systems based on urethane oligomers and silicates." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00689865.
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L'objectif de cette recherche est d'établir des mécanismes de formation de la structure des systèmes hybrides organique-inorganique à base des oligomères uréthane et silicates en fonction de la réactivité de la composant organique, d'identifier l'impact de l'organisation structurelle du OIS obtenue sur leurs propriétés électriques et thermomécaniques, de sorption et de l'activité du capteur. La signification pratique des résultats est la détermination de l'impact de la réactivité composant organique sur la structure des systèmes hybrides polymère organique-inorganique avec la possibilité d'obtenir des matériaux avec des propriétés spéciales prévisibles. Les résultats peuvent être utilisés comme base scientifique pour comprendre l'interconnexion de la structure, les propriétés et les moyens de leur régulation en direction de systèmes hybrides polymère organique-inorganique. La sensibilité très élevée pour les différents types de solvants, qui, combiné avec une haute sélectivité, a été révélé pour les systèmes de synthèse, la possibilité de leur utilisation pratique en tant que matières capteur existe.
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Li, Mei. "Preparation of urethane-acrylic hybrid miniemulsion nanoparticles /." Diss., 2002. 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:3048964.
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Lin, Yo-Shao, and 林育劭. "Phase Transitions and Morphology Siloxane-Ether Urethane Copolymer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/19563698741778077006.
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碩士萬能科技大學
工程科技研究所
93
Siloxane-ether urethane (PDMS/PTMG-PUBD) and siloxane-ether-imide urethane (PDMS/PTMG-PUIM) copolymers prepared from a one step method in the N,N-Dimethyformamide(DMF)/tetrahydrofuran(THF) mixed solvent. The soft-segment of PDMS/PTMG-PU copolymers consist of polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) and hard-segment is urethane segment reacting from 1,4-butane diol(1,4-BD) and 4,4-diphenylmethane diisocyanate(MDI). The soft segment of PDMS/PTMG-PUIM was similar to PDMS/PTMG-PUBD but hard-segment is a imide segment consisting of 3,3', 4,4'-Diphenylsulfone-tetracarboxylic Dianhydride(DSDA) and MDI. The phase-separation degree of copolymers was lower than that the non-polar PDMS polyurethane because the copolymers incorporated PTMG in the soft-segment to increased the miscibility between soft segment and hard segment. The PDMS/PTMG-PUBD and PDMS/PTMG-PUIM in the differential scanning calorimeter (DSC) exhibited soft- and hard-segmented phase-transition. The soft-segmented phase-transition PDMS/PTMG-PUBD and PDMS/PTMG-PUIM including the PDMS and PTMG amorphous phase-transition but the crystal phase-transition only presented on the melting-quenched PDMS/PTMG-PUIM copolymers. There were two endothermal regions, which were respectively the short-range ordering and the long-range ordering of hard segment domains(Region I and II), displaying at around 100℃ and 160℃. The endothermic behavior was demonstrated by annealing measurement displaying was a enthalpy relaxation resulting from prolonged physical aging. Furthermore, the hard-segmented crystal (Region III) appeared on the high hard-segment content of PDMS/PTMG-PUBD sample annealing for a period.
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Chiu, Hsien-Chang, and 邱憲章. "Thermal Degradation Characteristics of Siloxane-Ether Urethane Copolymer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/36760374872465685986.
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碩士萬能科技大學
工程科技研究所
94
Siloxane-ether urethane (PDMS/PTMG-PU) and siloxane-ether-imide urethane (PDMS/PTMG-PUIM) copolymers were synthesized in this study. The hard segments consisted of 4,4-diphenylmethane diisocyanate (MDI) and 1,4-butane diol (1,4-BD) or MDI and 3,3’,4,4’-diphenylsulfone tetracarboxylic dianhydride (DSDA). The soft segments were mixture of poly(tetramethylene glycol) (PTMG) and polydimethylsiloxane diol (PDMS). TGA measurement indicated that the degradations of copolymers were obviously distinguished into two stages. The degradation in the first stage was the decomposition of urethane hard segments. The urethane segments were composed of urethane-B (MDI and 1,4-BD ), urethane-S (MDI and PDMS) and urethane-G (MDI and PTMG) due to the various structures. The TG and DTG curves showed individual degradation region of these urethane segments. They also presented various activation energies calculated by Ozawa method. The degradation in the second stage was breakdown of PDMS and PTMG soft segments. The degradation of two soft segments was unable to discriminate absolutely due to the mixing ratios of PDMS and PTMG. The degradation of PDMS produced cyclics by interaction of siloxane bonds. The interactions among cylics formed macrocyclics. The degradation of copolymers with high PDMS content in the range of high temperature emerged the degradation behavior of macrocyclics. TG-IR analysis exhibited that the degradation of PDMS/PTMG-PU copolymer were along the sequences of urethane-B and urethane-G, PTMG and PDMS, macrocyclics. These for PDMS/PTMG-PUIM copolymer were urethane-G, imide, PTMG and PDMS, macrocyclics.
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Cheng, Wei-Yuan, and 鄭磑元. "Study of Aliphatic Urethane Acrylate UV-curing Coatings." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/b38ybp.
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碩士國立臺北科技大學
有機高分子研究所
105
This purpose is discussed the physical properties of the radical light-cured coating performance on ABS materials. Use with different acrylic monomers and acrylic resin light curable coatings reach on the physical properties of ABS materials adhesion, hardness, abrasion more improved. Radical curing system having acrylic group 1,6-Hexanediol Diacrylate(HDDA)、Dipentaerythritol Hexaacrylate(DPHA), added photoinitiator (1-hydroxycyclohexyl phenyl ketone) and leveling agent(Polyether modified silicone), and is to 600mj/cm2 of UV light energy. Cross hatch test paint adhesion on ABS materials, In pencil hardness meter test paint on ABS materials, In RCA abrasion meter test paint on ABS materials, In Fourier transform infrared spectrometer (FTIR) to test for different coating composition, In Dynamic Mechanical Analysis (DMA) to test Glass Transfer Temperature (Tg), In Thermogravimeteric Analysis (TGA) to test Degraded Temperature (Td), With a variety of match to reach the photo curable coating properties can be improved. As test results, DPHA were improved properties of hardness and abrasion obviously.
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Jang, Shin-Cheng, and 張欣程. "Synthesis and Physical Properties of Siloxane-Urethane Copolymer." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/22519219672495032590.
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博士逢甲大學
紡織工程所
96
Siloxane-urethane copolymers and siloxane-urethane-imide copolymers were synthesized by one-step process. Siloxane-urethane copolymers prepared from polydimethylsiloxane diol (PDMS) with a molecular weight 1000 or 1800 which was used as a soft segment, 4,4''-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (1,4-BD). Siloxane-urethane-imide copolymers prepared from PDMS with a molecular weight 1000 or 1800, MDI and pyromellitic dianhydride (PMDA). The hard segment of conventional polyurethane displayed one stage of degradation. Siloxane-urethane copolymers exhibited two types of urethane hard segments (urethane 1 and urethane 2). Urethane 1 consisted of MDI and 1,4-BD. Urethane 2 consisted of MDI and PDMS. The characteristics of degradation in the urethane hard segments demonstrated by TGA analysis and Ozawa method presented two types of temperature. Therefore, urethane hard segments of siloxane-urethane-imide copolymers were urethane 2. Their characteristics temperature of degradation in the first stage increased with the imide group contents. The degradation temperature of PDMS soft segment was higher than hard segment and the maximum temperature occurred at 480 °C. Furthermore, a cyclosiloxane of decomposition produce resulted from thermal decomposition of PDMS at the temperature, and subsequently produced macrocyclics beyond 480 °C. The siloxane-urethane-imide copolymers exhibited the degradation in the third stage. This degradation was the decomposition of imide group. The initial temperatures of degradation in the third stage were constant at various imide group contents. However, these maximum temperatures of degradation increased with the increasing in the imide group contents. Differential scanning of calorimetry (DSC) demonstrated that the position (Tgs) and breadth (ΔB) of soft-segment glass transition of siloxane-urethane copolymers remained constant as the hard-segment contents increased. Heat capacities at soft segment glass transition of copolymer (ΔCp) changed with the various hard and soft segment contents, leading to the various ΔCp/ΔCp0 ratios. The various heat capacities were attributed to the polar ether end-group of PDMS prepolymer. The result confirmed that the ether end-group of the soft segment led to interfacial mixing between soft and hard segments. The tanδ of the soft segment determined by dynamic mechanical testing (DMA) also identified the mixing of soft and hard segment. The Tgs and ΔB of soft-segment glass transition of siloxane-urethane-imide copolymers raised as the hard-segment contents increased. The ΔCp/ΔCp0 ratios were consistent with the Tg and �婿 shown. These results demonstrated the copolymers with higher imide group contents displayed less phase separation. The thermal behavior of amorphous hard segment for the copolymer with 62.3 % hard-segment content was studied by differential scanning calorimetry (DSC). Upon annealing at 100 °C, both the T1 temperature and magnitude of the T1 endotherm increased linearly with the increase in logarithmic annealing time. This phenomenon was typical of enthalpy relaxation resulting from the physical aging of amorphous hard segment. Upon annealing above 100 °C, the T1 endotherm shifted to high temperature until its merger with the T2 endothermic temperature. The T2 multiple endotherm appeared between 180 °C and 240 °C at 170 °C annealing temperature and its magnitude increased with the annealing time, indicating that the increase of range order.
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Tzeng, Shr-Gung, and 曾士恭. "Studies on UV-curable Poly(urethane acrylate) Resin." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/93735945589867174545.
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碩士國立臺灣大學
化學工程學研究所
92
UV curable polyurethane acrylate resins based on polyoxypropylene glycol(PPG) soft segment with different molecular weights were synthesized in this study. The kinetics of UV curing under different UV exposure doses, at various photoinitiator concentration was investigated and the kinetic equation was derived. In addition, UV curable urethane-acrylate resins were considered as reactive acrylate monomers as reactive diluents: Tripropylene Glycol Diacrylate(TPGDA) and Acrylic acid(AA). Further more, physical properties of this type of UV curable material, the effects on properties by varying the molecular weight of PPG and the effect of using various reactive diluents were discussed. The internal reference peak of acrylate group（=C-H Out-of-plane bending,990cm-1） was methyl group （CH3 bending~1375cm-1）. The peak changes were tracked with FTIR. The results reveal that the kinetic rate equation for the concentration of acrylate group which UV exposure is first order, and for UV exposure dose is one-half order, and the UV exposure relationships is proportional to (1-exp(-2.303ε[PI]d))0.5. The tensile strength and elongation at break of UV curable films increased with increase of AA concentration .The thermal decomposition temperature of UV curable films decreased with increase of AA concentration .The glass transition temperature(Tg) of UV curable films shifted to a higher temperature as the content of AA increased .This was interpreted in terms of possible compatibility of urethane hard segments and carboxylic acid group of AA due to their similar polarity and hydrogen bonding. In the adhesion test, it reveals that resin with increase of AA concentration show higher adhesion to the PET film.
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Lin, Shih Jyun, and 林士君. "Synthesis and Characterizations of New Poly(urethane-amine)Dendrimer." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/60691526534778373735.
Full textAbstract:
碩士嘉南藥理科技大學
生物科技系
101
The aim of this study is preparation of polyurethane dendrimers (PUAD-EIA, PUAD-OH,PUAD-NH2) by divergent method.The chemical structure of the dendrimer was indentified by fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR).To evaluate their physical and chemical properties, we executed a series of experiments. The particles size was characterized by transmission electron microscopy (TEM). Zeta-potential analyzer was also performed to understand surface properties of polymer. Acid-base titration studies was performed to determine the buffering capacities.The MTT assay was used to assess the cytotoxicity of polymers, in addition, observed the hydrolysis ability and analysis of drug solubility. We found that the synthesized dendritic polymer is biodegradable, nano-sized,and can increase the solubility of poorly water-soluble drugs. From above data, polyurethane dendrimers can be used as an ideal gene and drug delivery system.
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Chen, Yen-Jung, and 陳妍蓉. "Novel Urethane-acrylate Root Canal Sealer:Cytotoxicity and Antibacterial Effect." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/20050485394139068873.
Full textAbstract:
碩士國立臺灣大學
臨床牙醫學研究所
99
For sealing off of the root canal system after completely cleaning and shaping, the standard root canal filling is a combination of sealers with gutta-percha cone. The ideal root canal sealer needs good biocompatibility and antibacterial effect. Our research team has developed dual-cured urethane-acrylate (UA) sealer. Theses materials have good handling characteristics and bonding strength. For further research about the safety of urethane-acrylate sealer. The purposes of this study were to investigate the cytotoxicity and antibacterial effect of UA sealer. The results showed the PC-based UA sealer and Apexit have lower cytotoxicity than PBA-based UA sealer and commercial products such as Endorez, AHplus and Tubliseal. In antibacterial effect test, AHplus has higher antibacterial effect and UA sealers have lower antibacterial effect than other commercial products. We conclude that the cytotoxicity and antibacterial effect have correlations, and the higher bactericide effect may also kill the normal cell. PC-based UA sealer with higher conversion rate and good biocompatibility has high potential for clinical use.
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WANG, HSING-LUNG, and 王興龍. "Study on Polyether Poly(urethane-urea) as Polymer Electrolyte." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/95147117805778380880.
Full textAbstract:
碩士國立成功大學
化學工程學系
88
The behaviors of lithium ions in a polyether poly(urethane urea) (PEUU) were investigated by Differential Scanning Calorimetry (DSC), Fourier Transform Infra-Red (FTIR) spectroscopy, AC Impedance and magic angle spinning (MAS) solid state NMR measurements. The PEUU, used in this study, is composed of polyethylene glycol (PEG, mol. wt. 1000) as the soft segment and 4,4’-methylene bis(cyclohexyl isocyanate) extened with ethylene diamine (EDA) as hard segment. DSC experiments indicate the formation of transient cross links between Li+ ions and the ether oxygens on complexation with LiClO4, resulting in an increase in soft segment Tg. From the FTIR study, an appreciable change in the free as well as both of the hydrogen bonded —NH stretching bands has been observed, which suggests possible interactions of Li+ ions with both hard and soft segments of PEUU. The Arrhenius-like behavior of AC conductivity with reciprocal temperature suggests an activated hopping mechanism for transport of the charge carriers where the charge-carriers are decoupled from the segmental motion of the polymer chains. Significant line broadening, slight upfield chemical shift and short TCH, observed in the 13C NMR spectra for the carbons attached to the ether oxygens as the dopant was added into the polymer, indicates that a coordination between the Li cation and the ether oxygens in the soft segments. A systematic modeling analysis for composite electrolytes prepared by impregnating the ternary composites consisting polyethylene glycol based poly(urethane-urea) (denoted as PEUU(PEG)), polytetramethylene glycol based poly(urethane-urea) (PEUU(PTMG)), and polyethylene oxide (PEO) with LiClO4-PC. The results of swollen weight and conductivity at ambient temperature for composite electrolytes were fitted as empirical regression equations by using mixture design. These empirical equations were plotted as contour diagrams. The results indicates the composite electrolytes showed appropriate conductivities (liquid-like)only when swollen weight were over than 25 %.
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Lin, Mai-Jane, and 林美珍. "Mechanistic Studies of Rhenium Complexes Catalyzed Urethane Formation Reaction." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/00601543321349084470.
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