The essential novelty brought to crystallization by molecular length

There are two key features brought to crystallization by molecular length. First transverse lamellae which, for longer molecules, involves chainfolding and thence spherulitic growth. Second the basal lamellar surfaces; their formation is secondary to the crystallization of stems so that they are only well-defined for slow growth. For faster growth they are increasingly rough, unstable and prone to reorganization towards preferred packing in thicker lamellae. In tightly packed lattices such as polyethylene the associated excess energy drives twisted growth.