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 delta, which includes the linear growth rate of the crystal and diffusion coefficient of the amorphous (more mobile) component.

Crystallization of poly(ethylene oxide) confined in pores of active carbon.

The kinetics of isothermal crystallization of poly(ethylene oxide) confined in pores of active carbon was studied by nuclear magnetic resonance relaxation. At equal temperatures the induction period of crystallization in pores differs from that in the bulk polymer. A model was developed that allows estimation of the effect of porous media on the statistical sum of the macromolecule considering the change of the polymer chain conformation in the melt. This model describes the following observed effects: invariability of the induction period temperature dependence in pores, the weak temperature dependence of the ratio of induction period for e bulk, and pore material. The change in the induction period in cylindrical pores was predicted with satisfactory precision.