Stellenbosch University - Scopus Publications
Permanent URI for this collection
Metadata of articles were exported on 14 May 2011 from Scopus. Full text to be attached and moved to relevant Research Articles Collections per Department - Inquiries: SUNScholar or Tel.: 021 808 9139/9046.
Browse
Browsing Stellenbosch University - Scopus Publications by Subject "1-decanol"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- ItemSeparation of linear polyethylene from isotactic, atactic, and syndiotactic polypropylene by high-temperature adsorption liquid chromatography(2009) Macko T.; Pasch H.For the first time polyolefms are separated according to tacticity by liquid chromatography. High-temperature gradient HPLC is shown to be suitable for the separation of polyethylene and polypropylene. As the stationary phase a porous carbon-based material is used; the mobile phase is composed of 1-decanol and 1,2,4-trichlorobenzene. It is shown that at an operating temperature of 160 °C linear polyethylene as well as syndiotactic and atactic polypropylenes are fully adsorbed on the stationary phase from 1-decanol. In contrast, isotactic polypropylene is fully eluted. This behavior provides a novel way for liquid chromatographic separation of polyolefins. After the isocratic elution of isotactic polypropylene with 1-decanol, all retained components are desorbed from the column packing in a gradient of 1-decanol/1,2,4-trichlorobenzene. Nearly baseline-separated peaks are obtained for all components even in the case where the components do not differ in their molar masses. © 2009 American Chemical Society.
- ItemSeparation of propene/1-alkene and ethylene/1-alkene copolymers by high-temperature adsorption liquid chromatography(2009) Macko T.; Brull R.; Alamo R.G.; Thomann Y.; Grumel V.A high performance liquid chromatography column (HPLC) Hypercarb® packed with porous graphite has proven to discriminate polyolefin molecules due to differences in their adsorption and desorption behaviour. While linear polyethylene (PE) and syndiotactic polypropylene (sPP) are adsorbed on the graphite packing, isotactic polypropylene (iPP) is not adsorbed. The column operates at 160 °C with 1-decanol as sample solvent and mobile phase. We have now tested this HPLC system for separations of random propene/1-alkene and ethylene/1-hexene copolymers: While copolymers of propene with 1-butene, 1-hexene and 1-octene copolymers eluted in size exclusion mode without adsorption, propene/1-octadecene and ethylene/1-hexene copolymers are strongly retained and eluted only after application of a linear gradient starting from 1-decanol and ending with pure 1,2,4-trichlorobenzene. The retention of propene/1-alkene (>11 carbons in the side chain) copolymers increases with the concentration of comonomer, making this HPLC system suitable to separate these copolymers according to their chemical composition. In contrast, the retention of ethylene/1-hexene samples decreases with increasing 1-hexene content. Branching in this case shortens the length of continuous methylene sequences of the polymer backbone, which are expected to adsorb in a planar conformation to the graphite layers. This is the first report on the separation of short chain branched polyolefins by high-temperature adsorption liquid chromatography. © 2009 Elsevier Ltd. All rights reserved.