Orientation behavior of stereoregular poly(vinyl alcohols)

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Abstract
The orientation behavior of stereoregular poly(vinyl alcohols) was investigated during stretching and after releasing the stress on the bulk polymers at relatively high humidity (80% R. H.) A structural model, differing from polyethylene, was proposed in which the crystallites were embedded in a considerably swollen amorphous matrix without any definite physical interaction so as to form an aggregation of crystallites, a superstructure. The crystal orientation followed, in principle, “the first borderline case” of Kratky, but with some difference from theory in orientation, while the noncrystalline orientation was represented by the freely jointed equivalent chain model of Kuhn and Grün with a value of N/γ as small as around 5. The difference between crystal orientation found and the theorietical orientation is discussed and some factors which prevented the crystal orientation are considered.