Comments on the morphology of polymers crystallized from oriented melts
Molecular orientation due to melt flow has a profound effect on the nature of subsequent crystallization from the melt. This resulting crystalline morphology was examined with a polarizing microscope to understand the cases intermediate between quiescent melts on the one hand and highly oriented melts on the other. It seems unlikely that fibrillar nucleation along extended molecules occurs in general. Rather a more satisfactory picture is one in which the dominant orientation-dependent factor is a restriction of the lamellar growth to certain directions. This mechanism is emphasized as opposed to the concept of a direction-dependent growth rate or the earlier concept of fibrillar nucleation. A picture developed along these lines allows one to explain the entire spectrum of structure, ranging from spherulites on the one hand to “stacked lamellar” structure on the other.
KeywordsMolecular Orientation Stretch Ratio Crystalline Morphology Vibration Direction Primary Nucleus
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