Polyester cold drawn

In figure 7 we see on an insensitive range a sample of partially oriented polyester which has been shock-cooled and cold-drawn in spinning. At the glass transition the molecules sieze the opportunity to reorient causing a massive extension at the recrystallization point which continues right up to the melt. 

The crude polyester can be melted, extruded, and then cold drawn to form the textile fiber Dacron polyester, the outstanding features of which are its stiffness (about four times that of nylon 66), very high strength, and remarkable resistance to creasing and wrinkling. Because the early Dacron polyester fibers were harsh to the touch, due to... 

Because the polyesters they were working with at that time had melting points too low for use in textile products, a deficiency that has since been removed, the researchers returned to the polyamides (nylons) that had earlier been put aside. They soon found that these polymers, too, could be "cold-drawn to increase... 

Similar to other polyesters, PLA displays crystal polymorphism and four different crystal modifications have been identified so far, named a-, P-, y-, and e-forms. The a-form of PLA grows upon melt- or cold-crystallization, as well as from solution [18-25]. Hot-drawn, melt-spun, or solution-spun PLA fibers of a high-draw ratio show the P-form [21-23]. The y-form is obtained via epitaxial crystallization on hexamethylbenzene substrate [24] and the s-modification is a crystalline complex formed below room temperature in the presence of specific organic solvents such as tetrahydrofuran and Af,Af-dimethylformamide [25]. Besides these four main crystal polymorphs, two disordered modifications of the a-form, named a and a , were recently proposed for PLA. The a -crystals grow via melt- or cold-crystallization below 110 °C [21, 26-29], whereas the a"-form develops upon crystallization under special processing conditions, below the glass transition temperature and in the presence of carbon dioxide [30]. 

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