Compatibility and rheological properties of EVOH(poly(ethylene-co-vinyl alcohol)/Nylon6 blend was investigated. Solution blends of EVOH/ Nylon6 with various compositions were made by using hexafluoroisopropanol as solvent and used for FT-IR measurement. Hydrogen bonding mainly between hydrogen of hydroxyl group of EVOH and carbonyl group of Nylon6 was observed by spectral subtraction between FT-IR spectra. This interaction decreased with decreasing contents of Nylon6.
Melt blends of EVOH/Nylon6 with two different viscosities of Nylon6 were made by single-screw extruder. From a viewpoint of melting point depression and single glass transition, Melt blends of EVOH/ Nylon6 showed good compatibility or, at least, very fine dispersion, regardless of composition, resulting from specific interaction. In logG' vs. log G" plots for dynamic shear behaviors, good miscibility in Nylon6-rich compositions was confirmed and the formation of fine domain was observed in EVOH-rich compositions. These observation was consistent with FT-IR measurement. Complex viscosity in low frequencies of EVOH/Nylon6 blend showed the positive deviation from the simple-additive rule. These deviation resulted from the increase of the interchain friction by specific interaction in Nylon6-rich compositions and the interfacial contribution by formation of fine domains in EVOH-rich compositions.
Due to the viscosity ratio effect, blends with high viscosity of Nylon6 showed smaller domain and larger positive deviation in complex viscosity than blends with low viscosity of Nylon6, in EVOH-rich com- positions, especially at 20 weight percent of Nylon6. The considerable reduction of undesirable reactions of EVOH in solution blend, which took place at high temperature, was observed in Nylon6-rich compositions, resulting from the specific interaction between EVOH and Nylon6.
