Consulta: subjectFacets:"Polyurethane"
Registros recuperados: 10
Data/hora: 09/06/2024 12:41:04

Description and modeling of polyurethane hydrolysis used as thermal insulation in oil offshore conditions
Provedor de dados: 5
Autores: 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

Life time prediction of polymer used as thermal insulation in offshore oil production conditions: Ageing on real structure and reliability of prediction
Provedor de dados: 5
Autores: 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

Engineering development of flexible selectivity grids for Nephrops
Provedor de dados: 5
Autores: 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

Accelerated ageing of polyurethanes for marine applications
Provedor de dados: 5
Autores: 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

Biodegradable oil-based polymeric coatings on urea fertilizer: N release kinetic transformations of urea in soil
Provedor de dados: 63
Autores: 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

Electrospun novel nanocomposite comprising polyurethane integrated with ayurveda amla oil for bone tissue engineering
Provedor de dados: 42
Autores: JAGANATHAN,SARAVANA KUMAR; MANI,MOHAN P.
Abstract  Ayurveda oil contains numerous source of biological constituents which plays an important role in reducing the pain relief caused during bone fracture. The aim of the study is to fabricate the polyurethane (PU) scaffold for bone tissue engineering added with ayurveda amla oil using electrospinning technique. Scanning Electron Microscopy (SEM) analysis showed that the fabricated nanocomposites showed reduced fiber diameter (758 ± 185.46 nm) than the pristine PU (890 ± 116.91 nm). Fourier Infrared Analysis (FTIR) revealed the existence of amla oil in the PU matrix by hydrogen bond formation. The contact angle results revealed the decreased wettability (116° ± 1.528) of the prepared nanocomposites compared to the pure PU (100° ± 0.5774). The...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Polyurethane; Ayurveda oil; Electrospun scaffold; Blood compatibility; Bone tissue engineering.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652020000101101

Blood compatibility assessments of electrospun polyurethane nanocomposites blended with megni oil for tissue engineering applications
Provedor de dados: 42
Autores: JAGANATHAN,SARAVANA KUMAR; MANI,MOHAN P.; SUPRIYANTO,EKO.
Abstract: Tissue engineering holds as a prominent technique to repair or replace the damaged human parts to recreate its native function. In this research, a novel scaffold based on polyurethane (PU) comprising megni oil was electrospun for tissue engineering applications. The obtained polyurethane blended with megni oil nanofibers were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), contact angle measurement and atomic force microscopy (AFM). Furthermore, the blood compatibility of the fabricated nanocomposites evaluated through activated prothrombin time (APTT), partial thromboplastin time (PT) and hemolysis assay to determine the anticoagulant nature. The...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Polyurethane; Megni oil; Electrospun scaffold; Blood compatibility; Tissue engineering.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000300708

Early fragmentation of polyester urethane sheet neither causes persistent oxidative stress nor alters the outcome of normal tissue healing in rat skin
Provedor de dados: 42
Autores: 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

Electrospinning synthesis and assessment of physicochemical properties and biocompatibility of cobalt nitrate fibers for wound healing applications
Provedor de dados: 42
Autores: JAGANATHAN,SARAVANA KUMAR; MANI,MOHAN P.
Abstract: The aim of this study was to develop polyurethane (PU) wound dressing incorporated with cobalt nitrate using electrospinning technique. The morphology analysis revealed that the developed composites exhibited reduced fiber and pore diameter than the pristine PU. The electrospun membranes exhibited average porosity in the range of 67% - 71%. Energy-dispersive X-ray spectra (EDS) showed the presence of cobalt in the PU matrix. The interaction of cobalt nitrate with PU matrix was evident in Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The contact angle results indicated the improved wettability of the prepared PU/cobalt nitrate composites (82° ± 2) than the pure PU (100° ± 1). The incorporation of cobalt...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Polyurethane; Cobalt nitrate; Electrospun fibers; Skin tissue engineering; Physico-chemical characteristics; Bio compatibility.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000500901

Surface, thermal and hemocompatible properties of novel single stage electrospun nanocomposites comprising polyurethane blended with bio oilTM
Provedor de dados: 42
Autores: AYYAR,MANIKANDAN; MANI,MOHAN PRASATH; JAGANATHAN,SARAVANA KUMAR; RATHINASAMY,RAJASEKAR; KHUDZARI,AHMAD ZAHRAN; KRISHNASAMY,NAVANEETHA PANDIYARAJ.
ABSTRACT In this work, the physicochemical and blood compatibility properties of prepared PU/Bio oil nanocomposites were investigated. Scanning electron microscope (SEM) studies revealed the reduction of mean fiber diameter (709 ± 211 nm) compared to the pristine PU (969 nm ± 217 nm). Fourier transform infrared spectroscopy (FTIR) analysis exposed the characteristic peaks of pristine PU. Composite peak intensities were decreased insinuating the interaction of the bio oilTM with the PU. Contact angle analysis portrayed the hydrophobic nature of the fabricated patch compared to pristine PU. Thermal gravimetric analysis (TGA) depicted the better thermal stability of the novel nanocomposite patch and its different thermal behavior in contrast with the pristine...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Polyurethane; Bio oilTM; Nanocomposite; Atomic force microscopy; Wound healing.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652017000502411