A different approach to morphological diversity and surface nucleation in linear polyethylene

The classical Kossel–Stranski crystal model is adapted to a critical re-examination of surface nucleation in polyethylene. Several aspects of the diverse morphologies displayed by this polymer are well accounted for. The suggestion is made that curved {200} faces in lenticular crystals arise as a consequence of normal growth rather than nucleated growth on these faces. Processes generally involved in surface nucleation and subsequent layer spreading are discussed with emphasis upon entropic considerations. This leads to the view that, although nucleation kinetics are followed, molecular conformations can become more tightly clumped than is commonly thought to follow inevitably from layer spreading.