2007 Volume 23 Issue 7 Pages 815-821
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.