Microstructural characterization of semicrystalline copolymers by Raman spectroscopy

J.P. TOMBA; C. MANA; C. J. PÉREZ; M. DESIMONE; G. BARRERA GALLAND

POLYMER TESTING

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2016 vol. 52 p. 71 - 78

0142-9418

We employ Raman spectroscopy to characterize several microstructural aspects of a family of ethylenepropylene copolymers (EPC). Focus is made on the simultaneous analysis of crystallinity and chemical composition. A curve fitting procedure is used to isolate Raman bands ascribed to polypropylene chains in the crystal lattice from contributions of the amorphous phase. Crystal contents of EPC calculated on this basis are in the range 10e34 wt%, in good agreement with independent wide angle x-ray diffraction and differential scanning calorimetry measurements. Besides, Raman spectroscopy captures in some ofthe samples a mixed crystalline structure with both, polyethylene and polypropylene crystals, indicating a distinctive molecular architecture. The chemical composition of EPC is obtained from Raman spectra in the melt state to decouple peaks characteristics of the crystal lattice from fundamental vibrational modes of the polymer chain. EPC present ethylene contents in the range 5e26 mol%, in good agreement with parallel results from 13C nuclear magnetic resonance analysis. Remarkably, a rather complete characterizationof EPC can be achieved on the base of a single experimental technique.