Transcrystallinity in polypropylene

A study using hot‐stage microscopy and differential scanning calorimetry in assessing the ability of a number of substrates to nucleate transcrystalline growth in polypropylene is reported. Surface energy, chemical composition, crystal morphology, and moisture content of the substrate are discounted as being of importance in determining the ability of a substrate to nucleate polypropylene. It is concluded that surface topography plays a major role and it is argued that a prealignment of polymer chains occur in suitably sized cracks or channels on the surface. The rate of cooling the melt also dramatically influences the nucleating activity of a surface and this is ascribed to interfacial stresses resulting from differential contraction.