Polyester based cobalt concentrates for oxygen scavenging compositions

A polyester polymer concentrate is provided, comprising a transition metal in an amount of at least 1000 ppm to 40,000 ppm, and polyester polymers in an amount of least 40 wt.%, each based on the weight of the concentrate, wherein at least a portion of the polyester polymers comprise highly modified polyester polymers containing hydroxyl modifier residues in an amount ranging from 20 mole% to 60 mole%, based on the all the moles of hydroxyl compound residues present in the polyester polymer and/or polycarboxylic acid modifiers in an amount ranging from 20 mole% to 60 mole%, based on all the moles of polycarboxylic acid residues present in the polyester polymer. Concentrates made with highly modified polyester polymers are easy to compound with transition metals forming less brittle polymer upon melt extrusion. Bottle preforms and oxygen scavenging bottles can be made from these concentrates by combining solid polyester particles, solid polyamide particles, and solid these concentrate particles c into an melt processing zone, forming a melt, and forming an article directly from the melt. The b* color and the L* color and the haze levels of the preforms are improved over the preforms made with liquid carriers instead of solid concentrates.; The particles are also advantageously simultaneously dried in a drying zone under conditions effective to at least partially remove moisture from the blend to thereby further improve the b* color and L* color.