Polyamides and polyesters with improved mechanical properties

An attempt is made to establish the most proper initial structure for the obtaining of highly drawn (at room temperature) nylons and polyesters. It is found that neither the completely crystalline structure nor the fully amorphous one but a low-crystallinity, very imperfect structure (with a large number of small crystallites) is the most suitable one. Through ultraquenching of nylon 6 and PBT melts, and storage at ambient conditions, draw ratios of 7 and 8, respectively, are achieved. Subsequent annealing results in the obtaining of doubly higher values of the elasticity modulus and tensile stress. By means of WAXS, SAXS, IR spectroscopy, and DSC measurements the obtained structure is characterized. The highly drawn and annealed samples show a strongly reduced concentration of chain folds and a lack of long spacing.