ESTIMATION OF CRYSTALLINITY IN POLYETHYLENE BY RAMAN-SPECTROSCOPY

The quantitative determination of crystallinities of polyethylene samp les from the analysis of vibrational bands due to delta(CH2) twisting and nu(CC) stretching in the Raman spectra between 950 and 1500 cm-1 w as assessed. Several methods based on manual resolution of band envelo pes and on computer-derived information using Gaussian and Lorentzian profiles were compared. The major source of error was found to be the estimation of the amorphous and crystalline interphase content, alpha( b). A new method for the determination of sample crystallinity is prop osed based on the time-dependent Fourier transform deconvolution of th e spectral region between 950 and 1500 cm-1, which takes into account the baseline corrections and the influence of vibrational band shoulde rs in this region to obtain consistent values of alpha(a), alpha(b) an d alpha(c).