Polyester resins useful for forming containers having improved resistance to gas permeability comprising the reaction product of
(A) a dicarboxylic acid corresponding to the structure
wherein X is hydrogen or unsubstituted alkyl containing 1-5 carbons and n is an integer in the range of 4 to 10, and
(B) a diol selected from the group consisting of ethylene glycol, 1,4-butanediol and 1,4-cyclohexanedimethanol.