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Herbert Stutz - One of the best experts on this subject based on the ideXlab platform.
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surface tension interfacial tension and morphology in blends of thermoplastic polyurethanes and polyolefins part i surface tension of melts of tpu model substances and polyolefins
Polymer, 2002Co-Authors: Petra Potschke, Jurgen Pionteck, Herbert StutzAbstract:Abstract The pendant drop analysis was used to determine surface tensions γ of polymer melts. For thermoplastic polyurethane (TPU) elastomers, which are block copolymers of crystallisable hard segments (HS) and amorphous soft segments (SS), the surface tensions of the different segments in the melt were measured for the first time. As model compounds for the SS polyetherDiols (PEt-Diols) and a polyesterdiol (PEs-diol) were used. To suppress the influence of the hydroxyl end groups on the surface properties the Diols were either acetylated or chain extended with a diisocyanate. The influence of the molecular weight and the endcapping method was investigated. All TPU segments exhibit higher surface tensions than that measured for polyolefins due to their polar character except the acetylated PEt-Diols with γ -values between those of polypropylene and polyethylene. With 48–45 mN/m at 120–165 °C, the highest surface tension was determined for an amorphous HS model. The surface tensions of both PEs-Diols are higher than that of the PEt-diol model compounds. While the surface tensions of the acetylated and MDI extended PEs-Diols exhibit the same temperature dependence, differences were found between the surface tension of the acetylated and MDI extended PEt-Diols, which diminish with increasing molecular weight of the model substances.
Petra Potschke - One of the best experts on this subject based on the ideXlab platform.
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surface tension interfacial tension and morphology in blends of thermoplastic polyurethanes and polyolefins part i surface tension of melts of tpu model substances and polyolefins
Polymer, 2002Co-Authors: Petra Potschke, Jurgen Pionteck, Herbert StutzAbstract:Abstract The pendant drop analysis was used to determine surface tensions γ of polymer melts. For thermoplastic polyurethane (TPU) elastomers, which are block copolymers of crystallisable hard segments (HS) and amorphous soft segments (SS), the surface tensions of the different segments in the melt were measured for the first time. As model compounds for the SS polyetherDiols (PEt-Diols) and a polyesterdiol (PEs-diol) were used. To suppress the influence of the hydroxyl end groups on the surface properties the Diols were either acetylated or chain extended with a diisocyanate. The influence of the molecular weight and the endcapping method was investigated. All TPU segments exhibit higher surface tensions than that measured for polyolefins due to their polar character except the acetylated PEt-Diols with γ -values between those of polypropylene and polyethylene. With 48–45 mN/m at 120–165 °C, the highest surface tension was determined for an amorphous HS model. The surface tensions of both PEs-Diols are higher than that of the PEt-diol model compounds. While the surface tensions of the acetylated and MDI extended PEs-Diols exhibit the same temperature dependence, differences were found between the surface tension of the acetylated and MDI extended PEt-Diols, which diminish with increasing molecular weight of the model substances.
Jurgen Pionteck - One of the best experts on this subject based on the ideXlab platform.
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surface tension interfacial tension and morphology in blends of thermoplastic polyurethanes and polyolefins part i surface tension of melts of tpu model substances and polyolefins
Polymer, 2002Co-Authors: Petra Potschke, Jurgen Pionteck, Herbert StutzAbstract:Abstract The pendant drop analysis was used to determine surface tensions γ of polymer melts. For thermoplastic polyurethane (TPU) elastomers, which are block copolymers of crystallisable hard segments (HS) and amorphous soft segments (SS), the surface tensions of the different segments in the melt were measured for the first time. As model compounds for the SS polyetherDiols (PEt-Diols) and a polyesterdiol (PEs-diol) were used. To suppress the influence of the hydroxyl end groups on the surface properties the Diols were either acetylated or chain extended with a diisocyanate. The influence of the molecular weight and the endcapping method was investigated. All TPU segments exhibit higher surface tensions than that measured for polyolefins due to their polar character except the acetylated PEt-Diols with γ -values between those of polypropylene and polyethylene. With 48–45 mN/m at 120–165 °C, the highest surface tension was determined for an amorphous HS model. The surface tensions of both PEs-Diols are higher than that of the PEt-diol model compounds. While the surface tensions of the acetylated and MDI extended PEs-Diols exhibit the same temperature dependence, differences were found between the surface tension of the acetylated and MDI extended PEt-Diols, which diminish with increasing molecular weight of the model substances.
Magne O. Sydnes - One of the best experts on this subject based on the ideXlab platform.
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synthesis of trans dihydronaphthalene Diols and evaluation of their use as standards for pah metabolite analysis in fish bile by gc ms
Chemosphere, 2020Co-Authors: Caroline I Vaaland, Daniela M Pampanin, Magne O. SydnesAbstract:Abstract Phenols and trans-1,2-dihydro-1,2-Diols are metabolites commonly formed in vivo in fish upon exposure to polycyclic aromatic hydrocarbons (PAHs). These metabolites are excreted via the bile and gas chromatography-mass spectrometry (GC-MS) analysis of bile is becoming more frequently used for evaluating PAH exposure levels in fish. Current protocols focus on the detection and quantification of phenols formed during in vivo oxidation of PAHs, leaving out analyses and quantification of other oxidation products such as trans-1,2-dihydro-1,2-Diols, potentially underestimating exposure levels. Herein, four trans-1,2-dihydro-1,2-Diols, namely trans-1,2-dihydronaphthalene-1,2-diol, trans-6-methyl-1,2-dihydronaphthalene-1,2-diol, trans-5,7-dimethyl-1,2-dihydronaphthalene-1,2-diol, and trans-4,6,7-trimethyl-1,2-dihydronaphthalene-1,2-diol, were successfully prepared and used as standards in the GC-MS analysis, aiming to further develop this qualitative and quantitative analytical method for the determination of PAH exposures. This study shows that the currently used GC-MS analysis, including sample workup, is not suitable for determining the quantity of the corresponding Diols derived from naphthalene and methylated naphthalenes. Alternative approaches are needed to provide a correct estimate of PAH exposure levels.
Jacques Maddaluno - One of the best experts on this subject based on the ideXlab platform.
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synthesis of α β unsaturated dioxanes dioxolanes and dioxepanes by trans acetalisation of dimethylacetals with meso or c2 symmetrical 1 2 1 3 and 1 4 Diols
Tetrahedron, 2004Co-Authors: Loic Lemiegre, Fleur Lesetre, Jeanclaude Combret, Jacques MaddalunoAbstract:Abstract Several o -dibenzylic Diols were prepared reacting organometallics with o -phthalaldehyde at room temperature in ether. The identity of the meso and C 2 -symmetrical ( d , l ) isomers as well as their ratio were determined by chiral gas chromatography. The meso and C 2 (racemic) stereoisomeric Diols were easily separated by flash chromatography on silica gel. A set of 18 α,β-unsaturated acetals were then prepared reacting those, as well as commercially available 1,2, 1,3 and 1,4 Diols, with the corresponding methylacetals in acidic medium. A trans -acetalisation procedure adapted to the cases of fragile allylic alcohols or unfavorable 1,6 Diols-derived dioxonanes based on a Dean–Stark trapping of methanol was also employed.
