Polyamide grafting onto ethylene-vinyl alcohol copolymer

Ethylene-vinyl alcohol copolymers (EVOH), with appropriate barriers and processability, can be chemically modified through vinyl alcohol units. Amides and polyamides based on condensation reactions of adipoyl chloride and hexamethylenediamine were grafted onto EVOH. Grafting was characterized by contact angle measurement, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), nuclear magnetic resonance spectroscopy (NMR) and scanning electron microscopy (SEM). Amide peaks at 3302 cm(-1) corresponding to -NH bond stretching and the absorption of HN-CH2 at 7.8 ppm, were observed from ATR-FTIR and NMR, respectively, as a result of grafting. SEM showed the formation of amide structures as bundles, agglomerates and needle-like particles. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) showed considerable changes in onset of melt temperature, crystallinity and various transitions in grafted EVOH, showing an effective alteration in the physical properties compared with the virgin resin. Nylon grafted EVOH can be considered as a potential compatibilizer in polyethylene (PE)/polyamide blends via increasing interactions at the interface.