MORPHOLOGY AND INFRARED-SPECTROSCOPY OF STRONGLY INTERACTING POLYMER BLENDS - EVOH COPOLYAMIDE-6/6.9/

The presence of aliphatic hydroxyl groups in poly(ethylene-co-vinylalc ohol) (EVOH) suggests that these copolymers have the potential of form ing miscible blends, within certain composition ranges, with a variety of polymers containing complementary functional groups. Hydrogen bond ing in EVOH involves a wide variety of inter- and intramolecular speci es and plays an important role in the phase behavior of EVOH blends. P olymer blends of two random copolymers, EVOH with different ethylene c ontents and copolyamide-6/6.9 (COPA) at an approximately 1:1 comonomer ratio, were investigated using Fourier transform infrared (FTIR), nea r-IR, transmission electron microscopy (TEM), and scanning electron mi croscopy (SEM) methods. The blends were found to be partially miscible due to intermolecular hydrogen bonding between the OH group of the EV OH and the amide group of the copolyamide. The EVOH-rich blends exhibi t much lower;miscibility compared with the copolyamide-rich blends.