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The effects of additives on the distributions of lamellar morphology and orientation in sheared isotactic polypropylene were investigated using the small beam of synchrotron small-angle x-ray scattering. The Cu-phthalocyanine can template the lamellar orientation even under low shear rates, whereas the ultramarine blue cannot. The surface contact is suggested to play a role in stabilizing the formation of oriented nuclei which subsequently direct the growth of oriented lamellae. The additives have no notable effects on the long spacing in the shear region. However, at high shear rates, they decrease the thickness of crystalline lamellae or increase the thickness of amorphous lamellae. Since the additives increase the degree of volume crystalline in the shear region, the number of crystalline lamellae should be increased. The results are helpful in designing and selecting suitable additives for controlling lamellar morphology and orientation.

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