HYDRATION IN SEMICRYSTALLINE POLYMERS - SMALL-ANGLE NEUTRON-SCATTERING STUDIES OF THE EFFECT OF DRAWING IN NYLON-6 FIBERS

Water absorbed by nylons appears to be partitioned into interlamellar and interfibrillar spaces. The amount of water in the interfibrillar r egion remains essentially unchanged with increasing draw ratio, wherea s that in the interlamellar regions decreases with draw ratio; the lat ter accounts for the decrease in the water uptake in the drawn fibers. These results suggest that the amount of the amorphous material in th e interfibrillar regions remains unchanged during drawing, and the inc rease in the crystallinity during drawing results from the incorporati on of the amorphous chain segments in the interlamellar regions into t he crystalline lamellae. Further, the interfibrillar water is more tig htly bound than the interlamellar water. The length of the longitudina l channels into which water diffuses is about the same as that of the fibrils, and increases from ca. 1500 to 2000 Angstrom upon drawing. Th e longitudinal channels are highly oriented even in undrawn fibers, an d their misorientation increases from 5 degrees to 15 degrees upon dra wing. These channels can be described as surface fractals of dimension 3.4-3.6. (C) 1994 John Wiley and Sons, Inc.