CRYSTALLINITY DEGREE OF POLYETHYLENE TUBULAR BLOWN FILMS EVALUATED BY X-RAY-DIFFRACTION AND DENSITY METHODS - AN EVALUATION OF THE INTERFACIAL CONTRIBUTION

An experimental study is reported of the relationship between the degree of crystallinity of polyethylene tubular blown films obtained from x-ray diffraction and from density. The comparison shows that there are significant differences between the two techniques, and the values for percentage of crystallinity as determined by the density method are higher than those determined by the x-ray diffraction method. The main reason for these differences is the inclusion of the interfacial contribution to the measured density. The possible application of the analysis of the equation obtained for density crystallinity versus x-ray crystallinity in the evaluation of amorphous and crystalline domains in the interfacial region is discussed.