Influence of different beta-nucleating agents on the morphology of isotactic polypropylene and their toughening effectiveness

Abstract

The influence of two 1,3,5-benzenetrisamide beta-nucleating agents in comparison to a commercial bisamide beta-nucleating agent on the morphological and mechanical properties of isotactic polypropylene (iPP) is presented. To complete the study, the neat iPP and iPP containing a 1,3,5-benzenetrisamide alpha-nucleating agent was investigated. To evaluate the effectiveness of the different supramolecular polymer additives with regard to their influence on the toughness of iPP, a difficult-to-toughen high melt flow rate (MFR) iPP grade was selected. Investigations by wide-angle X-ray scattering (WAXS) confirm that the two 1,3,5-benzenetrisamides and commercial beta-nucleating agent induce the beta crystal modification of the polymer, whereas only the alpha modification is observed for the neat polymer and the 1,3,5-benzenetrisamide alpha-nucleating agent. Scanning electron microscopy (SEM) pictures on etched samples clearly reveal a shish-kebab structure in beta-nucleated iPP with 1,3,5-benzenetrisamides. For these two samples, Charpy impact investigations show a pronounced increase in toughness, also compared to the commercial bisamide beta-nucleating agent.