liquid crystal polymer (LCP) was blended with polyethylene terephthalate (PET) in different concentrations to improve the barrier properties of PET in injection stretch blow molded bottles. The improvement depends on the microstructure developed at various stages of the process. In this work, the emphasis is on the injection molding stage of the preform. The characteristics and number of morphological layers were directly related to the amount and type of LCP in the blend and the location within the preform. It was found that at 10% LCP, three morphological layers were found across the thickness of the part, while at 30% LCP, five morphological layers could be identified. The USP structure can be classified into four types: droplets, thick rods, thin fibrils and ribbons. Each morphological layer is made up of one or more types of structures. The evolution of one type of structure to another depends on the particular flow regime ongoing at various locations in the mold. This microstructure development, during the flow, was examined in detail.