HIGH-TEMPERATURE SEC CALIBRATION FOR POLYPROPYLENE USING A BROAD DISPERSITY STANDARD AND EVALUATION OF ITS MARK-HOUWINK CONSTANTS

Molar mass averages for polypropylene (PP) have been determined by hig h temperature size exclusion chromatography. A procedure based on the adjustment of linear fit, corresponding to that of a broad dispersity PP standard, has been found to give more accurate data as compared to that of universal calibration The method yields accurate results for s amples with a MWD similar to that of the standard. The Mark-Houwink co nstants, derived from the present work, have also been found to give m olar mass averages within close range of the standard values.