ABSTRACT
The mechanisms involved in the crystallization of polymer molecules, in the form of folded chain crystals [1] called lamellae, are now well understood [24]. The lamellar organization of polymers, crystallized both from solution and from the melt, is generally observed when the polymer chains are flexible and linear enough to fold back and forth in a lamella much thinner than the contour length of the polymer chain. When polymers are crystallized from dilute solutions at low supercoolings (high temperatures), single crystals are usually formed [2]. In optimal conditions, they are monolayered crystals with lateral dimensions in the range of 1-50 Am and a thickness between 5 and 15 nm. These chain-folded lamellar crystals usually have a geometric shape reflecting the symmetry of the polymer unit cell. Lamellae can also develop into fibrils and spherulites [2-4] when the polymer is isothermally crystallized from the melt.
