Non-isothermal crystallization of a vinyl alcohol-ethylene copolymer studied by DSC and real time WAXS/SAXS scattering

Time resolved SAXS/WAXS experiments, employing synchrotron radiation, together with DSC studies have been carried out on a vinyl alcohol-ethylene copolymer in order to clarify the morphological changes occurring during the non-isothermal crystallization of that copolymer from the melt. It was found that the SAXS long spacing and the WAXS diffraction peaks appear at the same temperature, revealing that the predominant growth mechanism of this process is nucleation and crystal growth but not density fluctuations. Moreover, the temperature variation of different structural parameters (peaks intensity, degree of crystallinity, long period, lamellar thickness) was comprehensively analyzed. Three temperature intervals are observed in this analysis, which have been interpreted as 'high-temperature crystallization', 'low temperature crystallization' and sub-glass region in order of decreasing temperatures.