Kinetics of crystallization of a flexible-chain polymer in pores

The kinetics of the isothermal crystallization of different fractions of po ly(ethylene oxide) in cylindrical pores of a carbon adsorbent having a pore diameter of 480 Angstrom was investigated by the NMR relaxation method. An alysis of the isotherm shape and of the temperature dependence of the cryst al growth rate showed that, for the polymer introduced into pores, the char acter of the primary nucleation and the crystallization regime are identica l to those for bulk systems at the initial stage of the crystal growth. The change in the isotherm shape was attributed to the one-dimensional geometr y of the growth, which was supported by the data on the character of the tr ansverse magnetization decay in the melt. It was found that the dynamic deg ree of crystallinity attained upon completion of the process, P-c(infinity) , depends on the crystallization temperature T-c: P-c(infinity) decreases w ith an increase in T-c. In the investigation of the subsequent melting of s amples, it was found that a decrease in T-c is attended with an increase of the fraction of the crystalline phase less ordered than lamellar crystalli tes. The transverse magnetization decay in amorphous regions during the cry stallization was represented as a sum of two components; one of them was as signed to the crystalline phase. The population of this component was found to be proportional to the degree of crystallinity, whereas relaxation time s of bath components were independent of this parameter.