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| 2. |
- Akhlaghi, Shahin, et al.
(författare)
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Deterioration of acrylonitrile butadiene rubber in rapeseed biodiesel
- 2015
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Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 111, s. 211-222
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Tidskriftsartikel (refereegranskat)abstract
- The deterioration of acrylonitrile butadiene rubber (NBR) exposed to rapeseed biodiesel at 90 degrees C was studied. The oxidation of biodiesel and NBR during ageing was monitored by H-1 NMR and infrared spectroscopy, HPLC and titration methods. The oxidation of biodiesel was impeded in the presence of NBR, but promoted in biodiesel-exposed rubber. This was explained as being due to the migration of stabilizer from the rubber to biodiesel, the diffusion of dissolved oxygen from biodiesel into NBR and the absorption of oxidation precursors of biodiesel by the rubber. The resemblance between the anomalous sorption kinetics of biodiesel in NBR and the equilibrium benzene uptake by the aged rubbers revealed that biodiesel caused a network defect in NBR, resulting in a gradual increase in the equilibrium swelling. The cleavage of crosslinks was implausible since the Young's modulus of the rubber at low strains, disregarding an initial decrease, increased with increasing exposure time. The appearance of 'naked' carbon black particles in the scanning electron micrographs of the aged rubbers and a drastic decrease in the strain-at-break of NBR after exposure to biodiesel suggests that internal cavitation was caused by the attack of biodiesel on the acrylonitrile units of NBR.
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| 3. |
- Akhlaghi, Shahin, et al.
(författare)
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Deterioration of automotive rubbers in liquid biofuels : A review
- 2015
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 43, s. 1238-1248
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Forskningsöversikt (refereegranskat)abstract
- Concerns over the fast depletion of fossil fuels, environmental issues and stringent legislation associated with petroleum-based fuels have triggered a shift to bio-based fuels, as an alternative to meet the growing energy demand in the transportation sector. However, since conventional automobile fuel systems are adapted to petroleum-based fuels, switching to biofuels causes a severe deterioration in the performance of currently used rubber components. The degradation of the rubber materials in biofuels is complicated by the presence of different additives in biofuels and rubber compounds, by oxidation of biofuels and by the effects of thermomechanical loadings in the engine. This paper presents a comprehensive review of the effects of different types of biofuels, particularly biodiesel and bioethanol, on the physical, mechanical, morphological and thermal properties of elastomers under different exposure conditions. In addition, the literature data available on the variation of rubbers' resistance to biofuels with the changes in their monomer type and composition, cure system and additives content was also studied. The review essentially focuses on the compatibility of biofuels with acrylonitrile butadiene rubber, fluoroelastomers, polychloroprene rubber and silicon rubber, as the most commonly used automotive rubbers coming into contact with fuels during their service. The knowledge summarized in this study can help to develop a guideline on the selection of rubber for automotive parts designed to withstand biofuels.
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| 5. |
- Hedenqvist, Mikael S., et al.
(författare)
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Sorption and desorption of tetrachloroethylene in fluoropolymers : Effects of the chemical structure and crystallinity
- 2003
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 87:9, s. 1474-1483
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Tidskriftsartikel (refereegranskat)abstract
- In 18 fluoropolymers with different repeating-unit structures and crystallinities, the solubility, diffusivity, and permeability at 70degreesC of a polarizable nonpolar solute (tetrachloroethylene) were studied. The transport properties were mostly controlled by the polarity of the polymer and to a lesser degree by the polymer crystallinity. The highest permeability was observed in the dipole-containing ethylene-chlorotrifluoroethylenes because of their high tetra chloroethylene solubility. The lowest permeability was observed in the hydrogen-bonding poly(vinylidene fluoride) polymers because of the combination of low solute solubility and solute diffusivity. The tetrachloroethylene diffusivity was solute-concentration-dependent, and sorption curves were S-shaped, indicating that the solute surface concentration was time-dependent. The rate at which the surface concentration approached the saturation level was proportional to the product of Young's modulus, the square of the thickness of the dry polymer, and the logarithm of the solute diffusivity. Data for the water-hyperbranched polymer and limonene-polyethylene conformed to the same relationship. Therefore, this provides a new tool for predicting the solute-surface-concentration time dependence from data obtained by independent measurements.
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| 6. |
- Hedenqvist, Mikael S., et al.
(författare)
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Structure and properties of poly(ethylene-co-chlorotrifluoroethylene) and polyvinylidene fluoride exposed to water, hydrochloric acid, hydrobromic acid and tetrachloroethylene
- 2004
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Ingår i: Polymer Engineering and Science. - : Wiley. - 0032-3888 .- 1548-2634. ; 44:1, s. 113-122
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Tidskriftsartikel (refereegranskat)abstract
- The transport of water, hydrochloric acid. hydrobromic acid and tetrachloroethylene in poly(ethylene-co-chlorotrifluoroethylene) and polyvinylidene fluoride were studied at 70degreesC by the sorption/desorption technique. The effects on the structure and mechanical properties were studied using size-exclusion chromatography, infrared spectroscopy, differential scanning calorimetry and tensile testing. Solute concentrations in the polymers indicated that both the water and HCl/HBr components diffused into the polymers on exposure to acid solutions. The calculated water contents of the diffusing acids generally differed from the water content in the solution. The ratio of water content in the diffusing acid to that in the surrounding acid solution was generally a function of the relative vapor activity of water and HCl/HBr. It was possible to describe the 35% HCl and 47% HBr desorption data using a two-component model. It was assumed that the water and HCl/HBr diffused separately, each having its own constant diffusion coefficient. The water diffusivity was obtained from the pure water system, and this allowed the HCl/HBr diffusivity to be calculated. It was found that the diffusivity decreased, in a non-simple way, as a function of solute size. The exposure to solute did not lower the molar mass of the polyvinylidene fluoride. Differential scanning calorimetry indicated the development of low-melting point polyvinylidene fluoride crystals during the exposure to all solutes. This seemed to be a consequence of the long-term exposure (175 to 376 days) at 70degreesC. The long-term exposure stiffened several of the polyvinylidene fluoride resins and occasionally made them less ductile. The poly(ethylene-co-chlorotrifluoroethylene) also became stiffer, but it was otherwise unaffected as far as observation by the other available techniques was concerned.
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| 9. |
- Tamborero, D, et al.
(författare)
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The Molecular Tumor Board Portal supports clinical decisions and automated reporting for precision oncology
- 2022
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Ingår i: Nature cancer. - : Springer Science and Business Media LLC. - 2662-1347. ; 3:2, s. 251-
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing need for systems that efficiently support the work of medical teams at the precision-oncology point of care. Here, we present the implementation of the Molecular Tumor Board Portal (MTBP), an academic clinical decision support system developed under the umbrella of Cancer Core Europe that creates a unified legal, scientific and technological platform to share and harness next-generation sequencing data. Automating the interpretation and reporting of sequencing results decrease the need for time-consuming manual procedures that are prone to errors. The adoption of an expert-agreed process to systematically link tumor molecular profiles with clinical actions promotes consistent decision-making and structured data capture across the connected centers. The use of information-rich patient reports with interactive content facilitates collaborative discussion of complex cases during virtual molecular tumor board meetings. Overall, streamlined digital systems like the MTBP are crucial to better address the challenges brought by precision oncology and accelerate the use of emerging biomarkers.
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| 11. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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