A series of chemically modified starch synthesized in the present study was blended with EVOH (having 27 mol % of ethylene component). The miscibility between the modified starch and EVOH was characterized by phase diagrams. The blends of a modified starch and EVOH was characterized by DSC. The DSC thermograms have shown a single glass transition temperature, suggesting a good miscibility between the modified starch and EVOH. We ascribed the miscibility in the blends to the formation of the hydrogen bonds between the hydroxyl groups in EVOH and a modified starch. Additionally, the DSC thermograms have shown a melting point depression and a decreasing melting enthalpy with the increase of the composition of the modified starch in the blends, suggesting that the crystallization of EVOH was interrupted by the modified starch. We also ascribed this interruption to the formation of the hydrogen bonds between a modified starch and EVOH. The FTIR spectra of the blends have shown a broad absorbance band of the hydrogen-bonded hydroxyl groups, which was located at a lower wavenumber than the absorbance band of hydrogen-bonded hydroxyl groups in neat EVOH, suggesting that the hydrogen bonds formed between a modified starch and EVOH in the binary blends are favored over the hydrogen bonds due to selfassociation in neat EVOH.
Furthermore, the crystalline structure of EVOH in the blends of a modified starch and EVOH was characterized by WAXD. In neat EVOH, the crystalline structure of EVOH takes orthorhombic lattice in the quenched specimen and evolves into monoclinic lattice as the crystallization temperature is increased. The WAXD patterns have shown that the crystalline structure of EVOH in the blends of a modified starch and EVOH did not change from that of neat EVOH. The tensile properties of blends of a modified starch and EVOH are found to have a positive deviation from linearity over the entire blend composition, indicating that the blends are miscible.