Nucleation effect of montmorillonite with β-nucleating surface on polymorphous of melt-crystallized isotactic polypropylene nanocomposites

Neat montmorillonite (MMT) causes strong heterogeneous nucleation of alpha-phase crystallites in isotactic polypropylene (iPP). By surface modification of MMT with pimelic acid (PA) MMT with tailored beta-nucleation capacity (beta-MMT) has been prepared and nanocomposites with beta-iPP have been made. The polymorphism of the iPP in the nanocomposites, the effect of beta-MMT on the morphology and its crystallization and melting behavior of iPP has been investigated by POM, DSC and XRD. beta-MMT raises the crystallization temperature to a higher value than neat MMT. The beta-nucleation ability of beta-MMT depends both on the MMT/PA ratio and on the beta-MMT content in the composite. The fraction of beta-crystals with respect to the total amount of crystals increases with increasing beta-MMT content and decreasing MMT/PA ratio. It can be adjusted between 0% and 98%. The accomplished surface modification of the MMT provides a simple and efficient way to prepare beta-ipp nanocomposites. (C) 2013 Elsevier Ltd. All rights reserved.