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Harald Pasch SASOL Chair of Analytical Polymer Science

Advanced Fractionation Techniques for Complex Polyolefins. Harald Pasch SASOL Chair of Analytical Polymer Science Department of Chemistry and Polymer Science, University of Stellenbosch, South Africa. Polyolefin Analysis. Complex Structures. New Applications. New Copolymers.

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Harald Pasch SASOL Chair of Analytical Polymer Science

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  1. Advanced Fractionation Techniques for Complex Polyolefins Harald Pasch SASOL Chair of Analytical Polymer Science Department of Chemistry and Polymer Science, University of Stellenbosch, South Africa

  2. Polyolefin Analysis Complex Structures New Applications New Copolymers Fractionation Techniques ? Chemical composition Molecular size TREF CRYSTAF HT-SEC

  3. Polyolefins – The Most Common Polymers polyethylene Where are the problems ? polypropylene

  4. Polyolefins just CH, CH2 and CH3 .... ????? Isotactic polypropylene (high crystallinity) Narrower PDI (Metallocene) Syndiotactic polypropylene Atactic polypropylene (low crystallinity) Broader PDI (Ziegler-Natta)

  5. Polyolefins just CH, CH2 and CH3 .... ?????

  6. Structures Density LDPE 0.935 0.929 -0.945 LLDPE HDPE 0.940 - 0.965 Why does chain structure influence properties? Branch type influences the crystal structure Distribution of the branches ???

  7. Results: SEM Change in Crystal Morphology as a Result of Blending LDPE 60% LDPE + 40% Plastomer poly(ethylene-1-octene)

  8. Molar Mass Analysis

  9. High-Temperature SEC Polymer Labs Model PL GPC 220 Stationary phase: Cross-linked PS Mobile phase: Trichlorobenzene Temperature: 140 oC Calibration: PS, PE Detectors: RI, ELSD, IR, LS, Vis

  10. HT-SEC and FTIR of an Oxidized Polyethylene ?

  11. LC- Transform Universal LC-FTIR Coupling pump + injector RI-detector Separation HPLC / GPC Identification FTIR spectrometer series of spectra

  12. SEC-FTIR of an Ethylene-Methacrylic Acid Copolymer

  13. SEC-FTIR Analysis of a Polyolefin Blend

  14. Separation by Crystallizability: Chemical Heterogeneity • Temperature Rising Elution Fractionation (TREF) • Crystallization Analysis Fractionation (CRYSTAF) CRYSTAF TREF HT-SEC  separation with regard to chemical composition

  15. Based on Flory-Huggins expression for polymer-diluent mixtures diluent: solvent, comonomer melting point depression is a function of non-crystallizable comonomer content chemical composition separation = separation by crystallizability Separation by Crystallizability: Chemical Heterogeneity

  16. Temperature Rising Elution Fractionation

  17. TREF Separation Mechanism The slow cooling rate is the most important factor in achieving good separation The slow cooling rate minimizes the effects of co-crystallization and molar mass influences. Typical cooling rates would be about 2°C/hour It takes about 2-3 days to cool!!

  18. Temperature Rising Elution Fractionation Comparison of typical LLDPE and LDPE

  19. Temperature Rising Elution Fractionation Hypothetical samples with same MMD and crystallinity distribution but different dependency on each distribution

  20. Temperature Rising Elution Fractionation Automatic Cross-Fractionation SystemTREF-SECS. Nakano, Y. Goto, J. Appl. Polym. Sci. 26 (1981) 4217

  21. Temperature Rising Elution Fractionation TREF-SECAnalysis of a Blend of Two PolyethylenesS. Nakano, Y. Goto, J. Appl. Polym. Sci. 26 (1981) 4217

  22. Crystallization Analysis Fractionation IR detector dW/dT W [%] 100 6 80 4 60 dW/dT W [%] 40 2 20 0 0 20 30 40 50 60 70 80 90 Temperature [°C]

  23. Crystallization Analysis Fractionation

  24. Crystallization Analysis Fractionation Typical temperature cycle Typical crystallization curve

  25. Crystallization Analysis Fractionation Crystaf analysis of a PP blend Comparison of TREF and CRYSTAF

  26. CRYSTAF: Analysis of Copolymers and Blends HDPE LLDPE HDPE/LDPE 4:96 HDPE/PP 50 : 50

  27. CRYSTAF: Analysis of Copolymers and Blends Propene--Olefin Copolymers Propene-Octene Propene-Octadecene

  28. CRYSTAF (in particular when coupled to IR sensor) excellent technique but very time consuming Fast and selective techniques are required liquid chromatography is a good candidate Polyolefins are soluble only at high temperatures unconventional stationary and mobile phases ???

  29. Elution Behaviour of Polyolefins in High Temperature Chromatography (HT-HPLC) Using Interactive Stationary Phasespolyolefin must dissolve in the mobile phasescreening of solubilitypolyolefin must interact with the phase systemscreening of mobile and stationary phases

  30. Solvents and Columns Decaline Trichlorobenzene Cyclohexanone Dimethylformamide normal phase systems: SiO2 (ZrO2, TiO2, Al2O3) reversed phase systems: Diol… CN… Phenyl… C8… C18 polarity polarity

  31. Screening of Stationary Phases for HT-HPLC Stationary phase: dimethylsiloxane-modified silica gel Benzylalcohol x Cyclohexylacetate DMF Cyclohexanone

  32. Screening of Stationary Phases for HT-HPLC Stationary phase: dimethylsiloxane-modified silica gel, solvent: TCB SEC conditions with regard to PP () Limiting conditions with regard to PE () mobile phase: EGMBE

  33. Screening of Stationary Phases for HT-HPLC Stationary phase: dimethylsiloxane-modified silica gel, solvent: TCB PP: SEC PE: Limiting conditions PP 36k + PE 34k PP 57k + PE 66k PP 438k + PE 500k mobile phase: EGMBE

  34. Analysis of PE-PMMA Block Copolymers: SEC and FTIR PMMA PE ? Multimodal distribution blend or copolymer ? MMA and ethylene units can be identified, but is it a copolymer or a polymer blend ? Chemical composition as a function of molar mass ?

  35. Analysis of PE-PMMA Block Copolymers: Coupled SEC-FTIR PE PMMA Chemical composition as a function of molar mass is visualized ! Homopolymers and copolymers can be identified ! PE-b-PMMA PE

  36. Analysis of PE-PMMA Block Copolymers What about interaction chromatography ? SEC molar mass separation LC-CC chemical composition separation

  37. Analysis of PE-PMMA Block Copolymers: Gradient HPLC Column: Nucleosil 300 C18 Temperature: 140C Mobile phase: gradient from100 % DMF to 100 % TCB PMMA PE PE-b-PMMA

  38. Analysis of PE-PMMA Block Copolymers: Gradient HPLC-FTIR ---- PMMA 1730 cm-1 ----- PE 720 cm-1 PE High-Temperature Gradient HPLC as a New Tool for the Analysis of Olefin Copolymers PMMA PE-b-PMMA

  39. Polymer Labs‘ High-Temperature Gradient HPLC System

  40. Separation System for PE-PP Blends PP PE M % TCB signal Time [min]

  41. Separation System for PE-PP Blends PE PP propylene-rich ethylene-rich PP column: Nucleosil 500 mobile phase: EGMBE-TCB T: 140oC detector: ELSD sample solvent: TCB EP copolymer with 48% ethylene L.-C. Heinz, H. Pasch, High-Temperature Gradient HPLC for the Separation of Polyethylene-Polypropylene Blends.Polymer 46 (2005) 12040

  42. Separation System for EVA Copolymers stationary phase: silica gel mobile phase: gradient of decaline-cyclohexanone PVAc PE A. Albrecht, R. Brüll, T. Macko, H. Pasch: Separation of Ethylene-Vinyl Acetate Copolymers by High-Temperature Gradient Liquid Chromatography.Macromolecules 40 (2007) 5545

  43. Separation of Polyolefins by Tacticity stationary phase: carbon-based mobile phase: gradient of 1-decanol-TCB

  44. Schematic Protocol for 2D Separations

  45. DataProcessing Two-Dimensional Chromatography (HPLC vs. SEC) 1. Dimension: HPLC/LCCC Degasser Pump Injector HPLCColumn 2. Dimension: GPC Degasser Pump Detector SEC Column Waste

  46. High-Temperature 2D-HPLC in Stellenbosch

  47. High-Temperature 2D-HPLC Chromatographic conditions: Stationary phase: Hypercarb Mobile phase: gradient of decanol-TCB Operating temperature: 160 oC Ginsburg, A., Macko, T., Dolle, V., Bruell, R., Europ. Polym. J. 47 (2011) 319-329

  48. High-Temperature LC-NMR

  49. High-Temperature LC-NMR ELSD Transfer line HT Stop-flow valve HT-SEC Transfer line

  50. polyethylene polymethyl methacrylate copolymer EtMMA

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