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Seven dicarboxylates of calcium were synthesized. The effect of dicarboxylate on the formation of ␤-form polypropylene was investigated by X-ray diffraction. Calcium pimelate, calcium suberate, calcium phthalate, and calcium terephthalate have been found to be an effective ␤-nucleator.The K x values of the isotatic propylene samples with 0.5 wt % of the nucleators above are 0.95, 0.96, 0.93, and 0.62, respectively. Calcium succinate, calcium adipate, and calcium sebacate behave invalidly on the nucleating of the ␤-phase. We conducted an investigation on the affect of particle shape, crystal form, and crystallinity upon the level of the ␤-form. The X-ray diffraction of the effective nucleators reveals a common character that their first reflection locate at the d-spacing between 10 to 13 Å, indicating structural similarity of the nucleators with ␤-polypropylene. The nucleation mechanism is explained by the cooperative effect of the nonpolar and polar part of nucleating agents in the crystallization of polypropylene.

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