β-nucleators and β-crystalline form of isotactic polypropylene

Different levels of β‐form crystallinity in isotactic polypropylene (iPP) were produced by blending a series of additives. X‐ray diffraction analyses showed that the Kx values varied from 0 to 0.05. Indigosol Brown IRRD, Indigosol Red Violet IRH, Cibantine Orange HR, Indigosol Pink IR, Cibantine Blue 2B, Indigosol Golden Yellow IGK, and Indigosol Grey IBL were found to be effective β‐nucleators. The respective Kx values of the iPP samples containing the above seven β‐nucleators of 0.05 wt % are 0.54, 0.68, 0.82, 0.82, 0.86, 0.92, and 0.95. All the β‐nucleators possess fused benzene rings or heterocycles in their molecular structures. X‐ray diffraction studies on them revealed a mutual character in that the strongest or the second‐strongest reflections almost locate at the d‐spacing of 2.83 Å. The magnitude is about half of that of the β‐spherulites possess a bright color and that their Maltese Crosses display some concentric banding of a rather spiky, jagged character. Their lamellae exhibit a correlated and dendritic structure seen by a scanning electron microscope. © 1995 John Wiley & Sons, Inc.