The normal viscoelasticity of the amorphous component yields
a rapid exponential decrease of the amplitude of the longitudinal
accordion type oscillations in the defect areas of the macromolecule
in the crystalline core and in the amorphous layers on the folds containing surfaces of the lamellae. The macrornolecule in the amorphous layer and in crystal defects changes direction and, hence, cannot conserve the longitudinal oscillation. The jumping of this oscillation to neighboring molecules accelerates so much its decrease that the straight sections between the two surface layers are longitudinally completely, while those between any two defects, or between one defect and the surface layer nearly completely decoupled from the rest of the sample. The effect is enhanced by the fact that the basic wave length of the observed Raman scattering is a little smaller than twice the length of the oscillating straight section. Maximum of the vibration energy occurs inside these sections and not in the amorphous regions. Since the lateral decoupling is guaranteed by the smallness of lateral forces, each straight section oscillates as if it were completely independent of the short and long range crystalline
and amorphous environment. Only in such a case a simple conclusion on the distribution of straight chain sections can be deduced from the experiment
