A novel montmorillonite with β-nucleating surface for enhancing β-crystallization of isotactic polypropylene

Montmorillonite (MMT) generally has α-nucleating ability for isotactic polypropylene (iPP). A novel MMT with β-nucleating surface (β-MMT) supported by chemically calcium pimelate (CaA) was prepared through the chemical reaction between pimelic acid (HA) and calcium ion on the surface of MMT in the first time. Infrared spectrometry and thermogravimetric analysis confirmed the formation of CaA on the surface of MMT. The differential scanning calorimeter and X-ray diffraction illustrated that the iPP nanocomposites filled by MMT and β-MMT exhibit different heterogeneous nucleation. The heterogeneous nucleation of the prepared MMT surface has changed from α-nucleation into β-nucleation and a novel MMT with β-nucleating surface is obtained. Even, the heterogeneous β-nucleating ability of β-MMT is much stronger than that of CaA. Addition of MMT with β-nucleating surface into iPP matrix significantly increased the spherulite nuclei density and decreased the spherulite size, and can easily prepare the β-iPP nanocomposites with high relative β-phase content.