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Mihail Ionescu S. Sinharoy Zoran S. Petrović 《Journal of Polymers and the Environment》2009,17(2):123-130
The synthesis of telechelic polyacetals with terminal hydroxyl groups (polyacetal polyols), by the reaction of triethylene
glycol divinyl ether with dipropylene glycol in the presence of trimethylolpropane or other triols or diols as starters, in
acidic catalysis, has been studied. The synthesized liquid polyacetal triols and polyacetal diols were characterized by hydroxyl
number, viscosity, acidity, number average molecular weight (Mn), weight average molecular weight (Mw), molecular weight distribution (Mw/Mn), FT-IR spectra. The obtained polyacetals were transformed in cast elastomers by the reaction with the isocyanate Mondur
CD (modified diphenyl methane diisocyanate) with properties very close to the elastic polyurethanes obtained by using conventional
polyether triols, copolymers propylene oxide–ethylene oxide. The polyacetal polyols are suitable for the synthesis of elastic
polyurethanes (polyurethane elastomers, flexible polyurethane foams). Polyacetals are well known biodegradable polymers. Therefore,
the polyurethanes based on polyacetal polyols are expected to be biodegradable. 相似文献
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Aliphatic–aromatic polyols were synthesized by thiol–ene reactions (photochemical or thermal) using mercaptanized starting materials from bio-based compounds: limonene dimercaptan, thioglycerol, mercaptanized castor oil and isosorbide (3-mercaptopropyl) ether. Aromatic starting materials were phenols containing double bonds; ortho-allyl phenol (OAP, petrochemical-based) and eugenol (EUG, bio-based). The phenolic hydroxyl groups were blocked by alkoxylation with propylene oxide (PO) or glycidol (GLY) prior to use in thiol–ene reaction. The aromatic rings were attached to the mercaptans by reacting thiol groups with the double bonds of alkoxylated OAP (OAP–PO and OAP–GLY) and alkoxylated EUG (EUG–PO and EUG–GLY). These synthesized aliphatic–aromatic polyols were utilized for preparation of rigid polyurethane foams whose physical–mechanical properties were superior to those made only from bio-based aliphatic polyols. These rigid PU foams can be used in a wide range of applications; such as thermal insulation of freezers, buildings, pipes and storage tanks for food and chemical industries, as wood substitute, packaging materials and flotation materials. 相似文献
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Quantifying sediment-associated metal dispersal using Pb isotopes: Application of binary and multivariate mixing models at the catchment-scale 总被引:1,自引:0,他引:1
Graham Bird Paul A. Brewer Mariyana Nikolova Mihail Mollov 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):2158-2169
In this study Pb isotope signatures were used to identify the provenance of contaminant metals and establish patterns of downstream sediment dispersal within the River Maritsa catchment, which is impacted by the mining of polymetallic ores. A two-fold modelling approach was undertaken to quantify sediment-associated metal delivery to the Maritsa catchment; employing binary mixing models in tributary systems and a composite fingerprinting and mixing model approach in the wider Maritsa catchment. Composite fingerprints were determined using Pb isotopic and multi-element geochemical data to characterize sediments delivered from tributary catchments. Application of a mixing model allowed a quantification of the percentage contribution of tributary catchments to the sediment load of the River Maritsa. Sediment delivery from tributaries directly affected by mining activity contributes 42-63% to the sediment load of the River Maritsa, with best-fit regression relationships indicating that sediments originating from mining-affected tributaries are being dispersed over 200 km downstream. 相似文献
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