Determination of Short-Chain Branching Distribution of Polyethylene via IR5-GPC Youlu Yu* and Paul J. DesLauriers Chevron Phillips Chemical Company LP Bartlesville Research & Technology Center Bartlesville, Oklahoma 74006 February 27 – March 2, 2011 International Polyolefins Conference 2011 Hilton Houston North, Houston, Texas
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Determination of Short-Chain Branching Distribution of Polyethylene via IR5-GPC
Determination of Short-Chain Branching Distribution of Polyethylene via IR5-GPC. Youlu Yu * and Paul J. DesLauriers Chevron Phillips Chemical Company LP Bartlesville Research & Technology Center Bartlesville, Oklahoma 74006 February 27 – March 2, 2011 - PowerPoint PPT Presentation
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Determination of Short-Chain Branching Distribution of Polyethylene via IR5-GPC
Youlu Yu* and Paul J. DesLauriers
Chevron Phillips Chemical Company LP
Bartlesville Research & Technology Center
Bartlesville, Oklahoma 74006
February 27 – March 2, 2011
International Polyolefins Conference 2011
Hilton Houston North, Houston, Texas
Outline
Introduction Instrumentation Methodology
– Data handling/processing– Calibration– Error analysis
Practical Aspects Comparison with Other Techniques Conclusions
Conventional Techniques for PE SCB Distributional Determination
SGF-NMR– Classic method
• SGF Fractionation + NMR
– Off-line technique– Tedious & labor intensive– Limited resolution– Large quantity of solvent/waste
On-line SEC-FTIR– Pioneered by DesLauriers et al. (DesLauriers, Rohlfing, Hsieh,
2002, Polymer, 43, 159)– On-line technique– Fast turn-around– Chemometrics for data analysis– Liquid nitrogen needed– Batch mode
Desired Improvements in Online SCB Determination Technique
With today’s PE business environment where safer, faster, and cheaper operations are required, there are still rooms for improvements with the Online SEC-FTIR SCB determination technique in the following areas:
– Eliminating liquid nitrogen usage• Less human intervention• Less system upsets • Easier operation
– System suitable for continuous operations• Reduced human intervention• Improved productivity
– Easy/straight forward data processing
IR5 Detector
Manufactured by Polymer Characterization, S.A. Spain (J. Montesinos, R. Tarin, A. Ortin, B. Monrabal, 1st Internantional Conference of Polyolefins Characterization, 2006, Houston)
A fixed-band IR spectrometer with five optical filters for detection of adsorbance in five different mid-IR bands
Thermoelectrically-cooled MCT detector Advanced optics to achieve high energy throughput High temperature capability
Specifically designed for polyolefins characterization Minimal mixing in cell (cell volume 11.3 uL) No liquid N2 needed
Suitable for continuous GPC and high-throughput GPC applications
IR5-GPC Instrumentation
IR5Pump ColumnsInjector
Solvent Reservoir
Waste
Computer A Computer B
Data Box
SCB Calibration and Calculation
SCB calculation based on intensity ratios– Two intensity ratios tested: ICH3/ICH2 and
ICH3/Iall C-H
– Chain-end effect correction based on polymer chemistry (# CE/molecule)
Calibration curve (i.e. intensity ratio as a function of SCB content) needed
– Polymers of known SCB contents and with flat SCB distribution employed
– Data points influenced by chain-end effect excluded from the calibration
MW/MWD determined by the relative method using the integral calibration method and broad MWD PE standard
Both the “compensate” and “un-compensate” modes explored All data processing performed using in-house developed software
SCB Calibration and Calculation (E/H Copolymers)
Error Analysis
Uncertainty defined by signal to noise ratio (S/N)
Simulated SCB Error Map
28%
5%
Detection limit @ 0.5 – 1 SCB/1,000 TC if CH2 S/N at 2,000 – 3,000