Some new habit features in crystals of long chain compounds part III. Direct observations on unflattened monolayer polyethylene crystals

By special light optical observation techniques monolayer polyethylene single crystals could be examined in their uncollapsed configuration while still in suspension and related to their fully or partially collapsed forms seen electron-microscopically. The existence of the previously deduced non-flat based hollow pyramid was directly confirmed, but only as one, the most regular, of a range of other configurations which are corrugated forms with varying amounts of corrugations. The obliquities of the basal planes underlying all these forms are attributed to the fact that nearest-neighbour folds are not on the same level, this fold staggering arising from a double, left—right and back—front, asymmetry of the fold.