Determination of the percentage of homopolymer component in Ziegler/Natta catalyst linear low-density polyethylene resins using high-temperature cell Fourier transform infrared and partial least squares quantitative analysis technique.
A new method for the determination of the percentage of homopolymer component, using high-temperature cell Fourier transform infrared (FT-IR) by partial least squares (PLS) quantitative analysis technique, was developed and applied to Ziegler Natta linear low-density polyethylene (LLDPE). The method is based on the IR spectrum changes between the 730 cm(-1) band and 720 cm(-1) band at the temperature of 110 degrees C, which is near the melting point of the polyethylene. The HD % (the percentage of high-density component, i.e., the percentage of homopolymer component) results obtained by CTREF (CRYSTAF in TREF mode) technique are used as the input data together with the respective FT-IR spectra for PLS analyses to establish a calibration curve. The PLS quality is characterized by a correlation coefficient of 0.997 (cross-validation) using four factors and a root mean square error of calibration (RMSEC) of 0.772. The HD% of the unknown can then be predicted by the PLS software from the unknown FT-IR spectrum. A control resin was tested seven times by CTREF and FT-IR. The HD% of the control resin was 28.59+/-0.88% by CTREF and 29.05+/-2.37% by FT-IR. It was found that the method was applicable for the same comonomer type of LLDPE within a melt index range and density.
Cossar
Marlee
M
NOVA Chemicals Research and Technology Centre, Calgary, Alberta, Canada T2E 7K7. cossarm@novachem.com
Teh
Joo
J
Kivisto
Annikki
A
Mackenzie
Jason
J
D000465:Algorithms; D002384:Catalysis; D006358:Hot Temperature; D016018:Least-Squares Analysis; D008422:Materials Testing / Q000379:methods*; D008956:Models, Chemical; D015233:Models, Statistical; D020959:Polyethylene / Q000032:analysis* / Q000737:chemistry*; D011108:Polymers / Q000032:analysis / Q000737:chemistry; D015203:Reproducibility of Results; D012117:Resins, Synthetic / Q000032:analysis / Q000737:chemistry; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
D011108:Polymers; D012117:Resins, Synthetic; D020959:Polyethylene