Characteristic features of isothermal growth, thickening, and melting behavior of melt grown single crystals of low molecular weight poly (ethylene oxide) fractions are presented and discussed in terms of their relevance to basic concepts of polymer crystal growth. Measurements of growth (G) and thickening rates of once folded chain crystals were extended (up to the melting point) into a temperature range where usually only extended chain crystals grow. Monolayer extended and folded chain crystals melt by lateral shrinkage, the rate of which (G − ) depends not only on temperature, but also on thermal history. G − increases exponentially with the degree of superheating, and the value of the temperature coefficient d log G − /dT is proportional to the lamellar thickness. In the narrow temperature interval where transition from once folded to extended chain growth occurs, the crystal morphology displays some spectacular features. These may be accounted for in terms of the crystal habit and the rate of completion, g. of a molecular layer in the particular (hk0) prism face considered. Morphological analysis shows that g is of the same order of magnitude as G(hkO), leading to the conclusion that the growth of these PEO crystals is controlled by multiple surface nucleation rather than by deposition of a single surface nucleus.
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Kovacs et al. (1975) studied this question.