Compartmentalized chips of at least two chemically similar crystallizable thermoplastic polymers each having a different intrinsic viscosity placed in separate zones are disclosed. These compartmentalized chips exhibit thermal characteristics that are different from the traditional technique of homogeneously combining the two materials into the chip. These compartmentalized chips in their amorphous, crystalline and solid phase polymerized forms exhibit a longer crystallization half time than the homogeneous mixture, thus permitting faster injection cycle times.