Study of the non-isothermal crystallization of poly(ethylene oxide)/poly(methyl methacrylate) blends

Crystallization during cooling of a poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA) blend has been studied using differential scanning calorimetry. Five different cooling rates V, have been used (namely 10, 5, 2.5, 1.25 and 0.625°Cmin-1). The presence of PMMA for a given V, reduces the overall PEO crystallization rate. This effect can be ascribed to reduction of the mobility of the crystallizable chains due to the presence of the amorphous component. It was found that in quasi-static conditions at lower V,, when nucleation and growth processes are determined by a thermal mechanism alone, the experimental data for the pure PEO and the PEO/PMMA 90/10 and 80/20 blends agree quite well with the theoretical results obtained using the zero-order approximation of Ziabicki's theory. At higher V,, in the case of the blends, athermal nucleation cannot be neglected, and then the same approximation does not fit the experimental results. The experimental data analysed showed no agreement with Ozawa's theoretical predictions.