High-temperature gradient HPLC and LC-NMR for the analysis of complex polyolefins

2008 ◽  
Vol 80 (8) ◽  
pp. 1747-1762 ◽  
Author(s):  
Harald Pasch ◽  
Lars-Christian Heinz ◽  
Tibor Macko ◽  
Wolf Hiller
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Temperature Gradient ◽  
Molar Mass ◽  
Size Exclusion ◽  
Copolymer Composition ◽  
Composition Distribution ◽  
High Temperature Gradient ◽  
Chemical Composition Distribution ◽  
On Line

The synthesis and characterization of polyolefins continues to be one of the most important areas for academic and industrial polymer research. One consequence of the development of new "tailor-made" polyolefins is the need for new and improved analytical techniques for the analysis of polyolefins with respect to molar mass and chemical composition distribution. The present article briefly reviews different new and relevant techniques for polyolefin analysis. Crystallization analysis fractionation is a powerful new technique for the analysis of short-chain branching in linear low-density polyethylene (LLDPE) and the analysis of polyolefin blends and copolymers regarding chemical composition. For the fast analysis of the chemical composition distribution, a new high-temperature gradient high-performance liquid chromatography (HPLC) system has been developed. The efficiency of this system for the separation of various olefin copolymers is demonstrated. The correlation between molar mass and chemical composition can be accessed by on-line coupling of high-temperature size exclusion chromatography (HT-SEC) and 1H NMR spectroscopy. It is shown that the on-line NMR analysis of chromatographic fractions yields information on microstructure and tacticity in addition to molar mass and copolymer composition.

Degradation of unstabilised polypropylene and a propene- 1-pentene copolymer

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Stefan de Goede ◽  
Robert Brüll ◽  
Harald Pasch ◽  
Niall Marshall
Keyword(s):  
Chemical Composition ◽  
Mass Distribution ◽  
Molar Mass ◽  
Degradation Process ◽  
Size Exclusion ◽  
Molar Mass Distribution ◽  
Low Molecular Weight ◽  
Composition Distribution ◽  
Chemical Composition Distribution ◽  
Exclusion Chromatography

Abstract The degradation of polypropylene (PP) and a propene-1-pentene copolymer (P2) have been monitored with regard to chemical composition, molar mass distribution and chemical composition distribution. The increase in the carbonyl index can be monitored by IR and a decrease in molar mass can be observed from size-exclusion chromatography (SEC). CRYSTAF shows that the chemical heterogeneity of the samples broadens with continuing degradation. SEC-FTIR reveals that the degraded species are mainly found in the low-molecular-weight end of the molar mass distribution. Spatial heterogeneity of the degradation process has been proven by the analysis of abrased layers. It was found that the P2 copolymer degrades at a higher rate compared to PP.

High-throughput screening of the chemical composition distribution of random styrene-butyl acrylate copolymers

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Iván García Romero ◽  
Harald Pasch
Keyword(s):  
Chemical Composition ◽  
High Throughput ◽  
Butyl Acrylate ◽  
High Throughput Screening ◽  
Size Exclusion ◽  
Chemical Compositions ◽  
Composition Distribution ◽  
Chemical Composition Distribution ◽  
Exclusion Chromatography ◽  
Liquid Chromatographic

AbstractThe development of high-throughput liquid chromatographic techniques for the analysis of styrene-butyl acrylate (SBA) copolymers is discussed. The analysis time in size-exclusion chromatography (SEC) can be reduced to about 3 min per sample when high-throughput SEC columns and high flow rates are used. In gradient HPLC, small columns with improved separation efficiencies can be applied. The time requirements can be decreased to less than 2 min per sample. Using the high-throughput HPLC technique, the chemical composition distribution of high-conversion SBA copolymers can be analyzed in a fast and efficient way. The calibration of HPLC separation is conducted by coupling the HPLC system with FTIR through the LC-transform interface. A comparison of the chemical compositions of the copolymers obtained by 1H NMR, off-line FTIR and coupled HPLCFTIR verifies the accuracy of the high-throughput copolymer analysis approach.

Sign in / Sign up

Export Citation Format

Share Document