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| Registros recuperados: 10 | |
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| Davies, Peter; Evrard, Guy. |
| Polyurethanes are frequently used in underwater applications. They are required to resist the marine environment over long periods of immersion but the multiplicity of resin formulations makes material selection difficult. Accelerated tests are essential to guarantee long term integrity. This paper presents results from an experimental study in which polyurethane samples of two hardnesses, 40 and 90 Shore A, have been subjected to immersion in artificial sea water for periods up to two years at temperatures from 50 to 100 degrees C. In parallel samples have been immersed at sea in the Brest Estuary for up to five years. Mechanical properties have been measured on tensile specimens after ageing. The accelerated test results and FTIR analysis indicate that... |
| Tipo: Text |
Palavras-chave: Accelerated test; Sea water; Ageing; Marine; Polyurethane. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2822.pdf |
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| Bortoletto-Santos,Ricardo; Guimarães,Gelton Geraldo Fernandes; Roncato Junior,Vanderlei; Cruz,Diego Fernandes da; Polito,Wagner Luiz; Ribeiro,Caue. |
| ABSTRACT: Polymer coatings are used to control the rate of release of plant available nutrients from fertilizers as well as to reduce nutrient losses such as ammonia (NH3) volatilization. Although the literature presents several examples of materials used to coat urea, little is known about nitrogen (N) release properties such as the mechanism involved and phenomena (e.g., pore opening) in the polymer coating. Thus, this study investigated urea release from polyurethane (PU) derived from two renewable raw materials (castor oil and soybean oil), to explain how the oil structure and coating microstructure influence release and urea-N dynamics in soil. The results demonstrated that the profile of urea release and the urea-N mineralization in the soil could be... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Polyurethane; Controlled release; Plant nutrition; Soil fertility; Nitrogen. |
| Ano: 2020 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162020000101402 |
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| Le Gac, Pierre-yves; Choqueuse, Dominique; Melot, D.. |
| Polymers are widely used for passive thermal insulation coatings on steel pipe in offshore oil and gas production. In this industry, structures used in deep sea have to be reliable, as they are in service for more than 20 years in a very severe environment: sea water, hydrostatic pressure and temperature gradient. One of the main questions is how to test and predict the lifetime of such structures in the laboratory? This study presents one approach that has been developed to characterize and predict the degradation of polymers used as thermal insulation materials. This paper is dedicated to polyurethane (polyether based) degradation in sea water at high temperature. Ageing has been performed in natural sea water under hydrostatic pressure at temperatures... |
| Tipo: Text |
Palavras-chave: Polyurethane; Hydrolysis; Accelerated ageing; Sea water; Coating; Offshore. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00160/27132/25330.pdf |
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| SGROTT,SANDRO M.; NEVES,RODRIGO D.; D’ACAMPORA,ARMANDO J.; BERNARDES,GERALDO J.S.; BELMONTE,LUIZ; MARTINS,THIAGO C.; BOBINSKI,FRANCIANE; CARGNIN-FERREIRA,EDUARDO; HOEPERS,ANDREZA; COMIM,CLARISSA M.; MARTINS,DANIEL F.; PIOVEZAN,ANNA P.. |
| Abstract Silicone breast implant is associated with complications inherent to the surgical procedure. Prosthesis coating with polyurethane, however, commonly reduces the incidence of such complications. In this paper, the authors evaluated the inflammatory histomorphometric profile and oxidative damage associated to the implant of polyester urethane sheets. Forty-eight Wistar rats were divided into Sham or polyester urethane groups (n = 8/group) and underwent a polyester urethane implant in the dorsal skinfold. Tissue samples were collected on days seven, 30, and 90 after surgery and subjected to histomorphometric analysis and biochemical tests. Results were analyzed by one-way ANOVA (p ≤ 0.05). Peri-implant tissue samples exhibited characteristic... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Polyurethane; Inflammation; Cytokines; Oxidative stress; Wistar rats. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652018000502211 |
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| Loaec, Henri; Morandeau, Fabien; Meillat, Marc; Davies, Peter. |
| There are different approaches to selectivity, including increasing cod-end mesh size, square mesh panels and rigid grids. Selectivity grids have traditionally been produced to be as rigid as possible to maintain spacing but this can result in heavy, expensive grids, handling problems and brittleness. This paper presents an alternative approach using flexible polyurethane polymers to produce lightweight inexpensive grids with much improved damage tolerance and ease of handling, which also possess interesting selectivity characteristics. The material selection, design and development tests are described first, then preliminary sea trial results are presented. A flexible grid with a 20 mm spacing between bars performed successfully and enabled a reduction in... |
| Tipo: Text |
Palavras-chave: Damage resistance; Polyurethane; Nephrops; Grid; Size selection; By catch; Selectivity. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1690.pdf |
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| Le Gac, Pierre-yves; Choqueuse, Dominique; Melot, D.; Melve, B.; Meniconi, L.. |
| Polymers are widely used for passive thermal insulation coatings on steel pipe in offshore oil and gas production. In this industry, structures used in deep sea have to be reliable as they are in service for more than 20 years in a very severe environment: sea water, hydrostatic pressure, temperature. One of the main questions is how to test and predict the lifetime of such structures in the laboratory. This study presents one approach that has been developed to characterize and predict the degradation of polyurethanes used as thermal insulation materials. Based on results obtained during accelerated ageing of the PU in sea water, a prediction of degradation through the thickness has been set up taking into account the temperature profile in the coating,... |
| Tipo: Text |
Palavras-chave: Polyurethane; Life time prediction; Hydrolysis; Offshore; Thermal insulation; Durability. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00174/28572/26957.pdf |
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| Registros recuperados: 10 | |
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