Analytical Sciences

Simultaneous Prediction of Ethylene Content and Melt Temperature in Melt-state Polypropylene by Near-Infrared Spectroscopy and Chemometrics

Masahiro WATARI

Visiting Researcher, Department of Chemistry and Research Center for Near-Infrared Spectroscopy, School of Science and Technology, Kwansei-Gakuin University, Sanda 669-1337, Japan

This paper reports on a simultaneous prediction method for ethylene (C₂) content and the melt temperature in melt state random polypropylene (RPP) and block polypropylene (BPP) by near-infrared (NIR) spectroscopy and chemometrics. The NIR spectra of RPP and BPP in melt states were measured by a FT-NIR on-line monitoring system. The predicted values of the C₂ content from the RPP or BPP spectra measured at 190 and 250°C were investigated using a calibration model for the C₂ content developed by using each RPP or BPP spectra set measured at 230°C. The errors in the predicted values of the C₂ content depended on the pretreatment methods for each calibration model. It was found that a multiplicative signal correction (MSC) is very effective to compensate for the influence of the change of the RPP or BPP sample temperature on the predicted C₂ content. By using modified MSC, it was demonstrated that simultaneous predictions of the C₂ contents and the relative temperature of the melt RPP and BPP from the NIR spectra could be realized.

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