RAMAN-SPECTROSCOPY EMPLOYED FOR THE DETERMINATION OF THE INTERMEDIATEPHASE IN POLYETHYLENE

The original work of Strobl and Hagedorn suggesting the presence of a third intermediate phase in semicrystalline polyethylene was revisited . The current study, involving the collection of Raman spectroscopic d ata on a set of 16 polyethylene samples recorded on two different type s of instruments in two different laboratories and employing two diffe rent methods of curve fitting to both sets of experimental data, has r evealed that the claims in the original paper cannot be asserted. The most important reason leading to this conclusion is a problem incorrec tly describing the complicated overlapping spectral structure in the 1 000-1200 and 1400-1500 cm(-1) spectral ranges. It is noted that the co ntribution of the melt in the 1000-1150 cm(-1) range cannot be describ ed by a single line centered around 1080 cm(-1). The present results i ndicate that the quantification of a third, intermediate, phase in pol yethylene is not possible when based on standard Raman spectra.