ON THE ANALYSIS OF THE RAMAN INTERNAL-MODES OF CRYSTALLINE POLYETHYLENE

The Raman internal modes of a set of polyethylenes have been analyzed in order to quantitatively evaluate their phase structures. Samples were prepared that covered as wide a range in crystallinity level as possible. Four different methods were used to analyze the spectra. One involved the manual decomposition of the spectra, another a computer programmed decomposition. Two methods were used to approximate the Raman band shapes. In one, a combination of 60% Gaussian and 40% Lorenztian functions were used. In the other, an arbitrary combination of these two functions was chosen so as to give the best fit. It was found that all four methods gave essentially the same results. Thus, the criticism of the manual method was unwarranted. We have also confirmed previous results that the density determined level of crystallinity is equal to the sum of the core crystallinity and interfacial levels.