Infrared Spectroscopic Investigation of Hydrogen Bonding in EVOH Containing PVA Fibers

Fibers of poly(vinyl alcohol) (PVA) containing ethylene-vinyl alcohol copolymer (EVOH) are made by gel spinning. By using IR spectroscopy, the hydrogen bonds of the PVA/EVOH fibers with different EVOH content and different draw ratio are discussed. The peaks in the neighborhood of 3 400 cm–1 and the peaks near 3 600 cm–1 are used to analyze the hydroxyl absorption engaged in hydrogen bonds and the free hydroxyl absorption, respectively. As for PVA/EVOH films, with increasing EVOH content the H-bond is gradually weakened. As for fibers, however, with increasing EVOH content the strength of the H-bond increases, while the number of H-bonds is decreased. Similarly, with increasing draw ratio of the PVA/EVOH fibers, the strength of H-bond increases, while the number of H-bonds seems decreased. Higher EVOH content in the PVA/EVOH fibers causes a higher maximum draw ratio because of weakening of the H-bond. However, higher draw ratio does not always cause better mechanical properties of PVA/EVOH fibers.