Characterization of ethylene in EP and in iPP/EP systems by deconvolution of IR spectra

✍ Scribed by D. Daoust; S. Bebelman; N. Chaupart; R. Legras; J. Devaux; J. Costa

• Book ID: 101253493
• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 186 KB
• Volume: 75
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(20000103)75:1<96::aid-app11>3.0.co;2-m

✦ Synopsis

The purpose of this study is to propose a correlation between IR spectra and molecular structure of ethylene-propylene (EP) copolymers possibly blended with isotactic polypropylene (iPP). The method is based on the deconvolution of the spectrum in the CH 2 -rocking range, i.e., 800 -680 cm Ϫ1 , where the bands of interest overlap. The six bands present in this region were signal averaged in position and width. The spectra were then deconvoluted (curve fitted) assuming a Lorentzian shape for the bands. The band at 1167 cm Ϫ1 (with a shoulder at 1156 cm Ϫ1 ) corresponding to a CH 3 vibration is considered as an internal standard. The method was checked by varying some fitting parameters. In order to realize some quantitative measurements, calibration curves were established with some EP samples, characterized by 13 C NMR, which were used as standards. The amounts of total O(CH 2 OCH 2 )O units (ethylene units), isolated ethylene and structural defaults in PP were determined for different iPP/EP blends. Ethylene crystallinity has also been determined. A good correlation was evidenced between infrared and 13 C NMR measurements.