Nylon 6 was grafted with a zinc-neutralized ethylene/acrylic acid copolymer (CP) to produce four different modified polyamides (MPA) with varying CP content. These were mixed with four polyethylenes with different viscosities and the blends were blow-molded into bottles. The clearest MPA lamina was developed for blends with an optimum ratio of the viscosities of MPA and PE (VRoptimum), and bottles with the clearest lamina exhibited the best xylene permeation resistance, impact strength and the highest melting temperature (Tm). The value of VRoptimum increased with increasing CP content. A maximum improvement in barrier properties of MPA was found as the CP content reached about 15 wt%. The CP content of the MPA, however, only slightly affected the impact strength and xylene permeation resistance of the bottles.