title: Estimation of critical conditions of polymers based on monitoring the polymer recovery.
abstract: Liquid chromatography at critical conditions (LCCC) is a very attractive chromatographic technique on the border between the size exclusion and liquid adsorption mode of the liquid chromatography. The strong interest in LCCC arises from the fact that it is well suited to analyze the block lengths in segmented copolymers or the heterogeneities with regard to end groups present, for example, in functionalized polymers e.g., telechelics. In this paper a new method for identification of the critical conditions of synthetic polymers is proposed, which requires only one polymer sample with higher molar mass. The method is based on monitoring the recovery of the polymer sample from a column. The composition of the mobile phase is modified until the polymer sample is fully recovered from the column. The corresponding composition of the mobile phase is composition corresponding to LCCC. This new method was applied for the determination of critical conditions for polyethylene, syndiotactic polypropylene and isotactic polypropylene. The results of the new method will be compared to those of classical approaches and advantages will be pointed out.
authors.affiliation: Fraunhofer Institute for Structural Durability and System Reliability, Division Plastics, Group Material Analytics, Schlossgartenstrasse 6, 64289 Darmstadt, Germany; Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands.
authors.forename: S S
authors.initials: SS
authors.lastname: Bhati
authors.affiliation: Fraunhofer Institute for Structural Durability and System Reliability, Division Plastics, Group Material Analytics, Schlossgartenstrasse 6, 64289 Darmstadt, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Macko
authors.affiliation: Fraunhofer Institute for Structural Durability and System Reliability, Division Plastics, Group Material Analytics, Schlossgartenstrasse 6, 64289 Darmstadt, Germany. Electronic address: robert.bruell@lbf.fraunhofer.de.
authors.forename: R
authors.initials: R
authors.lastname: Brüll
mesh_terms: D000327:Adsorption; D002853:Chromatography, Liquid / Q000379:methods*; D008970:Molecular Weight; D020959:Polyethylene / Q000737:chemistry* / Q000302:isolation & purification*; D011126:Polypropylenes / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D011126:Polypropylenes; D020959:Polyethylene
keywords: HPLC; LCCC; Polyethylene; Polypropylene; SGIC of polyolefins