Structure formation of isotactic polypropylene from the glass

The structure formation process of isotactic polypropylene (itPP) from the glass into the "smectic" mesophase has been studied by small-angle x-ray scattering, wide-angle x-ray scattering and differential scanning calorimetry. The structure of the smectic phase was unaltered during the transition process, which indicates no spinodal decomposition process is present in the formation of the smectic phase from the supercooled melt in itPP. The long period of the nodular structure was 5 nm to 6 nm independent of annealing temperature lower than -15 degrees C. The glass transition temperature increased by the formation of the smectic phase from -30 degrees C to +1 degrees C. The mechanism of structure formation is discussed and a possible model is proposed.