title: On-line coupling of high temperature GPC and 1H NMR for the analysis of polymers.
abstract: The on-line coupling of gel permeation chromatography (GPC) and 1H NMR operating at temperatures up to 130 degrees C is presented. A NMR flow probe with a cell volume of 120 microL and a stop-flow valve are developed for on-flow and stop-flow NMR measurements at high temperatures. To maintain high and constant temperatures through the whole probe, the flow probe contains two separate heating circuits. A modified stop-flow valve is developed as a control device for enabling on-flow and stop-flow experiments at high temperature conditions. Heated transfer lines connect the flow probe with the high temperature GPC system. Due to their semicrystalline nature, polyolefins can be studied by liquid chromatography only at temperatures above 100 degrees C. The novel high temperature GPC-NMR system is used for the separation of complex polyolefins regarding their molar mass and for the analysis of different chemical structures. Blends of polyethylene, poly(methyl methacrylate), and ethylene-methyl methacrylate copolymers are separated according to the molar masses of the components. The compositions of the components are directly studied by on-line NMR. Moreover, the chemical composition distribution of an ethylene-methyl methacrylate copolymer sample is analysed. Differences between results of on-flow and stop-flow measurements are discussed.
authors.affiliation: German Institute for Polymers (DKI), Schlossgartenstr. 6, 64289 Darmstadt, Germany. whiller@dki.tu-darmstadt.de
authors.forename: Wolf
authors.initials: W
authors.lastname: Hiller
authors.forename: Harald
authors.initials: H
authors.lastname: Pasch
authors.forename: Tibor
authors.initials: T
authors.lastname: Macko
authors.forename: Martin
authors.initials: M
authors.lastname: Hofmann
authors.forename: Jürgen
authors.initials: J
authors.lastname: Ganz
authors.forename: Manfred
authors.initials: M
authors.lastname: Spraul
authors.forename: Ulrich
authors.initials: U
authors.lastname: Braumann
authors.forename: Roman
authors.initials: R
authors.lastname: Streck
authors.forename: Jeff
authors.initials: J
authors.lastname: Mason
authors.forename: Freddy
authors.initials: F
authors.lastname: Van Damme
mesh_terms: D002850:Chromatography, Gel / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods; D009862:Online Systems; D011108:Polymers / Q000032:analysis*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018511:Systems Integration; D013696:Temperature
chemical_list: D011108:Polymers; D011522:Protons