Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography
K N Prabhu1, R Brüll1, T Macko1
1Fraunhofer Institute for Structural Durability and System Reliability, Division Plastics, Group Material Analytics, Schlossgartenstrasse 6, 64289 Darmstadt, Germany.
Journal of Chromatography. A
|October 6, 2015
Summary
High-temperature two-dimensional liquid chromatography (HT 2D-LC) successfully separates bimodal high-density polyethylene (BiHDPE) by molar mass and composition. This method overcomes crystallization drawbacks, enabling detailed BiHDPE analysis.
Area of Science:
- Polymer Chemistry
- Analytical Chemistry
Background:
- Bimodal high-density polyethylene (BiHDPE) characterization is crucial for understanding polymer properties.
- Crystallization-based techniques have limitations in analyzing complex polymer distributions.
- High-temperature liquid chromatography (HT-LC) offers an alternative for polymer analysis.
Purpose of the Study:
- To optimize high-temperature two-dimensional liquid chromatography (HT 2D-LC) for analyzing BiHDPE.
- To investigate the impact of chromatographic parameters on molar mass and compositional separation.
- To enable the resolution of BiHDPE into its constituent high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) fractions.
Main Methods:
- Stepwise optimization of one-dimensional (1D) high-temperature high-performance liquid chromatography (HT-HPLC) parameters, including gradient slope and temperature.
- Hyphenation of HT-HPLC with high-temperature size exclusion chromatography (HT-SEC).
- Optimization of sample transfer loop volume for effective hyphenation.
- Application of infrared (IR) detection for enhanced analysis.
Main Results:
- Optimized HT-HPLC conditions minimized molar mass impact on compositional separation.
- Successful resolution of BiHDPE into HDPE and LLDPE constituents was achieved by optimizing the HT-HPLC to HT-SEC transfer.
- Infrared detection was demonstrated to be effective in HT 2D-LC of BiHDPE when chromatographic resolution is optimized.
- Bimodality of BiHDPE was clearly visualized in contour and 3D surface plots, as well as in HPLC and SEC projections.
Conclusions:
- HT 2D-LC is a powerful technique for characterizing the molar mass and chemical composition distribution of BiHDPE.
- The optimized method provides a valuable alternative to crystallization-based techniques.
- Successful application of IR detection in HT 2D-LC enhances the analysis of complex polymer samples like BiHDPE.
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