Structures and properties of injection moldings of crystallization nucleator-added polypropylenes. II. Distribution of higher-order structures

Flexural test specimens were injection-molded from polypropylenes added with 0.5 wt % calcium carbonate, talc, p-tert-dibutyl-benzoic acid monohydroxy aluminum, or p-dimethyl-benzylidene sorbitol under cylinder temperatures of 200–320°C. Distributions in the flow direction of higher-order structures such as a^*-axis-oriented component fraction [A^*] and crystalline orientation functions and distributions in the thickness direction of higher-order structures such as crystallinity, β-crystal content, the degree of b-axis orientation to the thickness direction, [A^*], and crystalline orientation functions were studied. These higher-order structures are inhomogeneous in the flow and thickness directions, which strongly influences the product properties such as mechanical and thermal properties.