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Academic literature on the topic 'Urethane A'

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Published: 4 June 2021
Last updated: 10 February 2022

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Journal articles on the topic "Urethane A"

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Tennebroek, R., J. Geurts, A. Overbeek, and A. Harmsen. "Self crosslinkable urethanes and urethane-acrylics." Surface Coatings International 83, no. 1 (January 2000): 13–19. http://dx.doi.org/10.1007/bf02692682.

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2

Field, K. J., and C. M. Lang. "Hazards of urethane (ethyl carbamate): a review of the literature." Laboratory Animals 22, no. 3 (July 1, 1988): 255–62. http://dx.doi.org/10.1258/002367788780746331.

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Urethane (ethyl carbamate) is used alone or in combination with other drugs to produce anaesthesia in laboratory animals. Although originally studied as a potential phytocide, urethane demonstrated antineoplastic properties when administered to rats with the Walker rat carcinoma 256. Subsequent trials in humans led to its use as a chemotherapeutic agent for various leukaemias. Mice develop pulmonary adenomas earlier in life and at a higher incidence following urethane administration. Urethane's carcinogenic influence is greater in neonatal mice; it also has a transplacental influence in mice. In rats, urethane increases the incidence of pulmonary adenomas, Zymbal Gland tumours, and a variety of other neoplasms. Urethane is absorbed sufficiently from the skin of laboratory animals to produce a transient narcosis. The carcinogenic effect appears to be due to an undefined oncogenic intermediate formed in the blood. Considering the properties urethane demonstrates in animals, the safety of its use by laboratory personnel is in question. However, if appropriate guidelines are followed, urethane should continue to be a useful anaesthetic agent for laboratory animals.
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Jalali, Shakeeba. "APPLICATION OF DYNAMIC MECHANICAL ANALYSIS FOR UV-CURED COATINGS." Chemistry & Material Sciences Research Journal 2, no. 2 (June 23, 2020): 55–59. http://dx.doi.org/10.51594/cmsrj.v2i2.138.

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The present study is about soya epoxy ester which was made by epoxy resin and fatty acid. Oleochemical polyols were prepared after the soya epoxy ester reacted with various hydroxyl and cellulose based derivatives. These oleochemical polyols were changed to urethanes prepolymers by reacting NCO groups of TDI and IPDI. By utilizing the reaction of NCO end group of urethane with HEMA, these urethanes were transformed in to urethane acrylate oligomer. By mixing the oligomers with various reactive diluents, UV curable coating compositions were derived. The methodology was based on dynamic mechanical analysis. The UV cured samples from cellulose based oleochemical polyols exhibit good mechanical and thermal properties. Their mechanical properties are more dependent on double bonds from unsaturated contribute to curing with extra cross-linking by an oxidative mechanism.
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Sotomayor, Rene E., and Thomas F. X. Collins. "Mutagenicity, Metabolism, and DNA Interactions of Urethane." Toxicology and Industrial Health 6, no. 1 (January 1990): 71–108. http://dx.doi.org/10.1177/074823379000600106.

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Urethane, a known animal carcinogen, has been the subject of intensive research efforts spanning 40 years. Recent concerns have focused on the presence of urethane in a variety of fermented foods and alcoholic beverages, although no epidemiological studies or human case reports have been published. Much information is available about the mutagenesis, metabolism, and DNA interactions of urethane in experimental systems. Urethane is generally not mutagenic in bacteria although in some instances it acts as a weak mutagen. Urethane is not mutagenic in Neurospora but is weakly mutagenic in Saccharomyces. Drosophila appear to be the only organisms that consistently give positive mutagenic results with urethane, but its mutagenicity is weak and in many cases shows no clear dose dependence. Urethane is a good clastogen in mammalian somatic cells in vivo, but it shows variable results with cells in vitro. It efficiently induces sister chromatid exchanges in a variety of cells. Mammalian spermatogenic cells are insensitive to the induction of specific locus and dominant lethal mutations by urethane. Mutational synergism has been reported to occur between ethyl methanesulfonate and urethane when administered two generations apart, and some investigators have suggested possible synergism for cancer-causing mutations in mice exposed to X-rays and urethane one generation apart. These studies are controversial and have not been confirmed. Studies on the induction of cancer-causing dominant mutations by urethane are at variance with results from extensive studies with the specific locus test in mice. Urethane studies with the unscheduled DNA synthesis assay in mouse spermatogenic cells and with the sperm abnormality test have given negative results. Urethane is rapidly and evenly distributed in the body. The rate of elimination of urethane from plasma is a saturable process and varies according to the strain and age of the animal. Recent studies have concentrated on the effect of ethanol on urethane metabolism. At concentrations similar to those in wine, ethanol inhibits the tissue distribution of urethane in mice. These results are important because they suggest a lower carcinogenic/mutagenic risk than expected from exposure to urethane in alcoholic beverages. Although research on the metabolic activation of urethane has been extensive, no conclusive results have been obtained about its active metabolite, at one time thought to be N-hydroxyurethane. More recently, it has been postulated that urethane is actived to vinyl carbamate and that this metabolite is capable of reacting with DNA. Vinyl carbamate is more carcinogenic and more mutagenic than the parental compound, but despite intensive efforts it has not been identified as a metabolite in animals treated with urethane. Urethane binding to DNA appears to correlate well with tissue susceptibility to cancer. Various studies have attempted to elucidate the molecular nature of the bound molecule and the binding site. Some results have indicated the formation of a single DNA adduct, 7-(2-oxoethyl)guanine. This adduct may isomerize to O6,7-(1'-hydroxyethano)guanine, which might be more mutagenic than the 2-oxoethyl adduct; however, this possibility seems unlikely. Despite extensive research, urethane's metabolism and molecular mechanisms of mutation are still not clearly understood.
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More, Ganesh Sunil, and Rajendra Srivastava. "Synthesis of amino alcohols, cyclic urea, urethanes, and cyclic carbonates and tandem one-pot conversion of an epoxide to urethanes using a Zn–Zr bimetallic oxide catalyst." Sustainable Energy & Fuels 5, no. 5 (2021): 1498–510. http://dx.doi.org/10.1039/d0se01912g.

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The one-pot tandem synthesis of urethanes directly from an epoxide, with urea in solvent-free condition using Zn2ZrOx is demonstrated. The catalyst exhibits excellent activity in cyclic urea, urethane, and cyclic carbonate production in neat conditions.
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&NA;. "Urethane." Reactions Weekly &NA;, no. 465 (August 1993): 12. http://dx.doi.org/10.2165/00128415-199304650-00056.

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Yen, Fu-Sen, Lieh-Li Lin, and Jin-Long Hong. "Hydrogen-Bond Interactions between Urethane−Urethane and Urethane−Ester Linkages in a Liquid Crystalline Poly(ester−urethane)." Macromolecules 32, no. 9 (May 1999): 3068–79. http://dx.doi.org/10.1021/ma9804186.

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8

Strel’nikov, Vladimir N., Valeriy Yu Senichev, Alexey I. Slobodinyuk, Anna V. Savchuk, and Elena R. Volkova. "Frost-Resistant Epoxy-Urethane Binders Containing Diglycidyl Urethane." International Journal of Polymer Science 2019 (April 21, 2019): 1–7. http://dx.doi.org/10.1155/2019/5670439.

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A novel method for developing frost-resistant epoxy-urethane binders is proposed that is based on mixtures of epoxy-urethane oligomers and diglycidyl urethane formed during synthesis. The microheterogeneous elastic materials obtained by curing these mixtures by the cycloaliphatic amines have a low glass transition temperature and high mechanical properties.
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Stakisaitis, Donatas, Raminta Mozuraite, Nomeda Juodziukyniene, Janina Didziapetriene, Saule Uleckiene, Paulius Matusevicius, and Angelija Valanciute. "Sodium Valproate Enhances the Urethane-Induced Lung Adenomas and Suppresses Malignization of Adenomas in Ovariectomized Female Mice." International Journal of Endocrinology 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/218219.

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In the present study, the possible effect of sodium valproate (NaVP) on urethane-induced lung tumors in female mice has been evaluated. BALB/c mice (n=60; 4–6 weeks old, females) were used in the following groups: (1) urethane-treated; (2) urethane-NaVP-treated; (3) only NaVP-treated; (4) control. In the same groups, ovariectomized female mice (n=60) were investigated. Urethane was given intraperitoneally, with a total dose of 50 mg/mouse. In NaVP-treated mice groups, 0.4% aqueous solution of NaVP was offered to micead libitum. The duration of the experiment was 6 months. The number of tumors per mouse in ovariectomized mice and in those treated with urethane and NaVP was significantly higher than in mice treated with urethane only (8.29±0.58versus6.0±0.63,p<0.02). No significant difference in the number of tumors per mouse was revealed while comparing the nonovariectomized urethane- and urethane-NaVP-treated groups (p=0.13). A significant decrease of adenocarcinoma number in ovariectomized mice treated with a urethane-NaVP as compared with ovariectomized mice treated with urethane only was found (p=0.031). NaVP together with low estrogen may have a protective effect on the malignization of adenomas in ovariectomized mice.
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Benson, R. Wayne, and Frederick A. Beland. "Modulation of Urethane (Ethyl Carbamate) Carcinogenicity by Ethyl Alcohol: A Review." International Journal of Toxicology 16, no. 6 (November 1997): 521–44. http://dx.doi.org/10.1080/109158197226865.

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Urethane (ethyl carbamate) is a carcinogen that has been detected as a contaminant in certain foods and alcoholic beverages. The carcinogenicity of urethane appears to be mediated through a metabolic pathway involving sequential cytochrome P-450-catalyzed oxidation to vinyl carbamate and vinyl carbamate epoxide, the latter of which reacts with DNA to yield etheno-type DNA adducts. The interactions of ethanol on urethane metabolism and carcinogenicity are varied and complex. Urethane is oxidized by cytochrome P-450 IIE1, an isoform induced by ethanol, which suggests that chronic ethanol consumption could increase the oxidation of urethane to its epoxide derivative. On the other hand, ethanol coadministration is known to inhibit the elimination and hydrolysis of urethane. Ethanol has decreased the tumorigenicity of urethane in two bioassays, but did not have an effect in a third. While the results to date suggest that ethanol will decrease the metabolic activation of urethane, with a resultant decrease in tumorigenicity, additional studies are clearly necessary to elucidate the mechanisms by which ethanol influences the carcinogenicity of urethane.
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Dissertations / Theses on the topic "Urethane A"

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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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Books on the topic "Urethane A"

1

Naylor, Steven. Microphase separation in segmented poly(ether-urethane)s. Manchester: UMIST, 1995.

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Timko, Robert J. Laboratory evaluation of spray-applied rigid urethane foams. Pgh. [i.e. Pittsburgh] Pa: U.S. Dept. of the Interior, Bureau of Mines, 1985.

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F, Jacobson Michael, ed. Tainted booze: The consumerʼs guide to urethane in alcoholic beverages. Washington, D.C: Center for Science in the Public Interest, 1987.

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Battye, William. Best management practices for pollution prevention in the slabstock and molded flexible polyurethane foam industry: Manual. Cincinnati, Ohio: U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 1997.

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Battye, William. Best management practices for pollution prevention in the slabstock and molded flexible polyurethane foam industry: Manual. Cincinnati, Ohio: U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 1997.

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Battye, William. Best management practices for pollution prevention in the slabstock and molded flexible polyurethane foam industry: Manual. Cincinnati, Ohio: U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 1997.

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Organization, World Health, and International Agency for Research on Cancer, eds. Alcohol consumption and ethyl carbamate. Lyon, France: International Agency for Research on Cancer, 2010.

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Zhang, Chen-xi. Synthesis and energy absorbing properties of polyurethane elastomers and soft foams based on immiscible soft segments. Aachen: Verlag Shaker, 1995.

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Bomberg, Mark. Spray polyurethane foam in external envelopes of buildings. Lancaster, Pa: Technomic Pub., Co., 1998.

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Chong, Shuang-Ling. Laboratory and test-site testing of moisture-cured urethanes on steel in salt-rich environment. McLean, VA: U.S. Department of Transportation, Federal Highway Administration, Research, Development, and Technology, Turner-Fairbank Highway Research Center, 2000.

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Book chapters on the topic "Urethane A"

1

Gooch, Jan W. "Urethane." In Encyclopedic Dictionary of Polymers, 784. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_12394.

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FRISCH, KURT C., and PANOS KORDOMENOS. "Urethane Coatings." In ACS Symposium Series, 985–1029. Washington, D.C.: American Chemical Society, 1985. http://dx.doi.org/10.1021/bk-1985-0285.ch041.

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Gooch, Jan W. "Urethane Coating." In Encyclopedic Dictionary of Polymers, 785. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_12395.

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Gooch, Jan W. "Urethane Foams." In Encyclopedic Dictionary of Polymers, 785. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_12396.

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Gooch, Jan W. "Urethane Plastic." In Encyclopedic Dictionary of Polymers, 785. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_12398.

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Gooch, Jan W. "Urethane Polymers." In Encyclopedic Dictionary of Polymers, 785. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_12399.

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Gooch, Jan W. "Urethane Resins." In Encyclopedic Dictionary of Polymers, 785. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_12400.

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Gooch, Jan W. "Thermoplastic Urethane." In Encyclopedic Dictionary of Polymers, 746. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_11803.

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Chance, R. R., H. Eckhardt, M. Swerdloff, R. R. Federici, J. S. Szobota, E. A. Turi, D. S. Boudreaux, and M. Schott. "Urethane-Substituted Polydiacetylenes." In ACS Symposium Series, 140–51. Washington, DC: American Chemical Society, 1987. http://dx.doi.org/10.1021/bk-1987-0337.ch011.

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Reiff, H., and D. Dieterich. "Urethane-based dispersions." In Ionomers, 444–76. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-1461-2_11.

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Conference papers on the topic "Urethane A"

1

Coseri, Sergiu, and Adrian Caraculacu. "Synergetic effect of urethane formation." In The 4th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2000. http://dx.doi.org/10.3390/ecsoc-4-01833.

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Lilis, Ioannis, Malamati Vreka, Magda Spella, Ioanna Giopanou, Antonia Marazioti, and Georgios Stathopoulos. "Macrophages promote urethane-induced lung adenocarcinoma." In Annual Congress 2015. European Respiratory Society, 2015. http://dx.doi.org/10.1183/13993003.congress-2015.pa4258.

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Nakamura, Yuji, and Shinichiro Ota. "Vibration Model of Cushion Having Foaming Urethane Within Air Cell." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70497.

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To control the vibration of the occupant by road-surface condition, we suggest a new seat cushion material (UA cell) which enclosed foaming urethane in an air cell in this study. We clarify the vibration characteristics of the UA cells by the excitation experiments and derive the theoretical model of the vibration characteristics of the UA cell. From the results, we understood that the relationship the thickness of the UA cell and that of foaming urethane had an influence on the vibration characteristics of the UA cell. When the thickness of the UA cell is smaller than the thickness of foaming urethane, the UA cells exhibit the vibration characteristics of the parallel spring which is built in foaming urethane and the air cell. When the thickness of the UA cell is larger than the thickness of foaming urethane, the UA cells exhibit the vibration characteristics of the air cell.
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Martel, Bryan. "Reclamation of Urethane Foam from Automotive Seats." In International Congress & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1998. http://dx.doi.org/10.4271/980095.

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Smith, A., L. D. Nield, M. Tennis, and R. L. Keith. "Inhaled Prostacyclin Prevents Urethane Induced Lung Adenocarcinoma." In American Thoracic Society 2021 International Conference, May 14-19, 2021 - San Diego, CA. American Thoracic Society, 2021. http://dx.doi.org/10.1164/ajrccm-conference.2021.203.1_meetingabstracts.a4830.

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Goda, Kengo, Osamu Furuya, Kohei Imamura, and Kenta Ishihana. "Laminated Type Isolation Device for Light Weight Structure Using Urethane Elastomer." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-66167.

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At the present, base isolation system has been recognized by general earthquake resistant technique since the Great Hanshin Earthquake 1995. The seismic isolation will be aggressively applied to not only architectural and civil structures but also various structures, because the effectiveness on seismic safety had been demonstrated again in the Great East Japan Earthquake. In generally, although the base isolation system is divided into laminated rubber bearing type and friction sliding bearing type. In the case of former type, shape factor, maximum or minimum outer shapes and so on are restricted by the material characteristics in visco-elastic material. In general, the isolation structure is used in high damping rubber. However, we pay attention to base isolation using urethane elastomer. Urethane elastomer has excellent elasticity, mechanical strength, abrasion resistance, weather resistance, oil resistance, impact resistance the absorbent, anti-vibration and excellent low-temperature properties. Furthermore, it is possible to impart various characteristics by a combination of isocyanate and polyol and chain extender, requires no large-scale apparatus, it has the advantage molecular design is easy. In previous study, the research and development of laminated type base isolation device using urethane elastomer was carried out to upgrade a seismic safety for various structures. The fundamental characteristics was investigated from several loading test by using various experimental devices, and the design formula for the stiffness and equivalent damping coefficient is formulated as an approximate expression of mechanical characteristics until now. It was confirmed that urethane elastomer is not hardening up to 500% shear strain. Moreover, the experimental examination for aged deterioration in the urethane material has been continuously carried out. As the results, it was confirmed that the laminated type seismic isolation device using urethane elastomer is possible to develop as a practicable device from the stable mechanical properties as considering in design step. In this study, the small-scale laminated type base isolation device using urethane elastomer is advanced to the direction of further technical upgrading and of scale down for light-weight structure as a sever rack. The first stage, basic properties of the urethane elastomer has been investigated by loading test. Furthermore, the design equation is created by loading test using urethane elastomer. The validity of the design equation has been confirmed. The second stage, the compression creep test with laminated type base isolation device has been investigated to confirm an effect on light-weight mechanical devices.
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Dempsey, Michael P., and Michael F. Hurley. "Advances in Urethane Foam Composites for Interior Trim." In International Congress & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1991. http://dx.doi.org/10.4271/910520.

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Suzuki, Masato, Yuki Ikejiri, Tsuyoshi Fukutani, and Seiji Aoyagi. "Tactile sensor using gelled poly-urethane ultrathin film." In 2009 IEEE Sensors. IEEE, 2009. http://dx.doi.org/10.1109/icsens.2009.5398395.

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Psallidas, Ioannis, Keparesia Karabela, Davina Simoes, Sophia Magkouta, Charis Roussos, Ioannis Kalomenidis, and Georgios T. Stathopoulos. "Secreted Phosphoprotein-1 Enhances Urethane-induced Lung Carcinogenesis." In American Thoracic Society 2010 International Conference, May 14-19, 2010 • New Orleans. American Thoracic Society, 2010. http://dx.doi.org/10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a2521.

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Ishihana, Kenta, Osamu Furuya, Kengo Goda, and Shohei Omata. "Study on Small-Scale Laminated Type Base Isolation Device Using Urethane Elastomer for Practical Application." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63992.

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At the present, base isolation system has been recognized by general earthquake resistant technique since the Great Hanshin Earthquake 1995. The seismic isolation will be aggressively applied to not only architectural and civil structures but also various structures, because the effectiveness on seismic safety had been demonstrated again in the Great East Japan Earthquake. In generally, although the base isolation system is divided into laminated rubber bearing type and friction sliding bearing type. In the case of former type, shape factor, maximum or minimum outer shapes and so on are restricted by the material characteristics in visco-elastic material. In previous study, the research and development of laminated type base isolation device using urethane elastomer was carried out to upgrade a seismic safety for various structures. The fundamental characteristics was investigated from several loading test by using various experimental devices, and the design formula for the stiffness and equivalent damping coefficient is formulated as an approximate expression of mechanical characteristics until now. The mechanical characteristics based on the loading test up to 500% shear strain using experimental specimen with 100 × 100 mm cross-sectional shape. It was confirmed that urethane elastomer is not hardening up to 500% shear strain. Moreover, the experimental examination for aged deterioration in the urethane material has been continuously carried out. As the results, it was confirmed that the laminated type seismic isolation device using urethane elastomer is possible to develop as a practicable device from the stable mechanical properties as considering in design step. In this study, the small-scale laminated type base isolation device using urethane elastomer is advanced to the direction of further technical upgrading and of scale down for light-weight structure as a sever rack. The first stage, basic properties of the urethane elastomer has been investigated by loading test. The second stage, the compression creep test with laminated type base isolation device has been investigated to confirm an effect on light-weight mechanical devices.
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Reports on the topic "Urethane A"

1

Watson, D. R. Urethane foam process improvements. Final report. Office of Scientific and Technical Information (OSTI), March 1995. http://dx.doi.org/10.2172/41306.

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Beitelman, Alfred D. Laboratory Evaluation of Moisture Cure Urethane Coatings. Fort Belvoir, VA: Defense Technical Information Center, September 2003. http://dx.doi.org/10.21236/ada418758.

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Edgar, Alexander S. Degradation Mechanisms of Poly(ester urethane) Elastomer. Office of Scientific and Technical Information (OSTI), November 2017. http://dx.doi.org/10.2172/1411335.

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Lafreniere, Robert A., and Roger Tryon. Dynamic Measurements of Three Urethane Hose Materials. Fort Belvoir, VA: Defense Technical Information Center, May 1995. http://dx.doi.org/10.21236/ada640492.

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Feuer, Henry O., Touchet Jr., and Paul. Failure Mechanism of Urethane Elastomer Coated Fabric Collapsible Fuel Tanks. Fort Belvoir, VA: Defense Technical Information Center, March 1990. http://dx.doi.org/10.21236/ada221033.

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DelCul, Guillermo D., C. M. Simmons, Alan S. Icenhour, and D. Singh. Radiolytic Degradation of Urethane Foam Used for Encapsulation of Contaminated Componets. Office of Scientific and Technical Information (OSTI), March 2006. http://dx.doi.org/10.2172/1096986.

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Casem, Daniel T., and Alex J. Hsieh. Plate-Impact Measurements of a Select Model Poly(urethane urea) Elastomer. Fort Belvoir, VA: Defense Technical Information Center, June 2013. http://dx.doi.org/10.21236/ada585929.

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L. Domeier, P. Keifer, and M. Hunter. Urethane Elastomers: Development of TDI-Free Replacement Materials for EN-7. Office of Scientific and Technical Information (OSTI), September 2000. http://dx.doi.org/10.2172/766630.

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WROBLESKI, DEBRA A., DAVID A. LANGLOIS, E. BRUCE ORLER, ANDREA LABOURIAU, MARIANA M. URIBE, ROBERT J. HOULTON, JOEL D. KRESS, and BRIAN K. KENDRICK. ACCELERATED AGING AND CHARACTERIZATION OF A PLASTICIZED POLY(ESTER URETHANE) BINDER. Office of Scientific and Technical Information (OSTI), September 2007. http://dx.doi.org/10.2172/1074589.

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Beitelman, Alfred D., and Jeffrey P. Ryan. Evaluation of Moisture-Cure Urethane Coatings for Compliance with Industry Specifications. Fort Belvoir, VA: Defense Technical Information Center, December 2011. http://dx.doi.org/10.21236/ada554426.

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