Nucleation and size distribution of nucleus during induction period of polyethylene crystallization.

The crystallization process from supercooled melt results in the formation of nanosize nuclei in the earlier stage (induction period) through subsequent attachment or detachment of repeating unit to nuclei. The size distribution of nucleus f(N(j),t) in the induction period of nucleation process from the melts has not been experimentally confirmed yet by direct observation. The reason is that the number density of nuclei nu is too small to be detected experimentally. In our previous work, we showed the direct evidence of nucleation experimentally by means of small angle x-ray scattering (SAXS) technique. Further we have succeeded to observe the nucleation and f(N(j),t) of polymer crystallization from the melts by SAXS using synchrotron radiation. We increased nu by adding a nucleating agent to a polymer (polyethylene). The time evolution of f(N(j),t) was observed for the first time.