Crystallisation of crystallizable and amorphous polymer mixtures and peculiarities of their structure: an NMR study

After isothermal crystallization of the crystallizable poly(ethylene oxide)/amorphous poly(propylene oxide) mixture, partially crystalline structures were formed. They present a specific heterogeneous medium with a hard frame composed of the crystal phase. The isothermal crystallization of the mixture and molecular self-diffusion processes in the amorphous phase of the crystallized mixture was studied by nuclear magnetic resonance relaxation and nuclear magnetic resonance (NMR) with pulsed field gradient. The temporal dependencies of the apparent self-diffusion coefficient were analyzed and the heterogeneity sizes were estimated. The dependence of the heterogeneity size on the crystallization temperature can be qualitatively described by parameter δ, which includes the linear growth rate of the crystal and diffusion coefficient of the amorphous (more mobile) component.