Disclosed is a process for injection stretch blow molding a thermoplastic composition comprising, consisting essentially of, or prepared from (a) about 30 to about 99 weight % based on the combination of (a) and (b) of a poly(ethylene terephthalate) homopolymer or copolymer; and (b) about 1 to about 70 weight % based on the combination of (a) and (b) of a poly(trimethylene terephthalate) homopolymer or copolymer, wherein the composition does not contain a crystallization accelerator.