Polymer blends suitable for packaging are disclosed that include a transition metal; one or more polyamide homopolymers or copolymers; and one or more polyethylene terephthalate homopolymers or copolymers obtained by a melt phase polymerization using a catalyst system comprising aluminum atoms in an amount, for example, from about 3 ppm to about 60 ppm and one or more alkaline earth metal atoms, alkali metal atoms, or alkali compound residues in an amount, for example, from about 1 ppm to about 25 ppm, in each case based on the weight of the one or more polyethylene terephthalate homopolymers or copolymers The polymer blends disclosed exhibit improved oxygen-scavenging activity compared with blends made using polymers prepared with conventional catalyst systems.