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Stress-induced straightening of tie chains in oriented PE films as revealed by Raman (LAM) study
Authors:Katherine Kober  I. A. Gorshkova  A. V. Savitsky  A. E. Tshmel
Abstract:
The Raman longitude acoustical mode (LAM) study of axially stressed polyethylene-made microfilms gave evidence of the formation of the straight tie molecules localized in two neighboring crystals and in an amorphous layer situated between them. The samples were bicomponent blends composed of polyethylenes with different MW (7 × 104 and 2 × 106). Each MW fraction exhibits an individual LAM band responding to crystals with the size specific to a given fraction. Under tensile stress, the bands shift insignificantly towards an exciting laser line. In addition, the LAM localized on all-trans sequencies with the length exceeding the mean crystallite size appear in the spectrum of a stressed sample. The reversibility of these spectral changes depends on the draw ratio of samples. We conclude the effect is due to stress-induced gauch-to-trans transformations taking place in the amorphous layers. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2829–2833, 1998
Keywords:Raman  LAM  stress  polyethylene
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