Polypropylene crystallization at an alumina interface using single walled carbon nanotubes.

Interfaces play an important and often limiting role in the mechanical, thermal, and electrical performance of composite materials. Here we suggest a novel method to improve the interfacial interaction in polypropylene-alumina composites using single-walled carbon nanotubes (SWNTs) to nucleate lamellar crystals at the interface. Macroscopic alumina substrates are used to determine the ideal crystallization parameters and investigate the kinetics of crystal growth. SWNTs are uniformly adsorbed to the interface via Van der Waals interactions and lamellar crystals are grown on the surface using isothermal solution processing techniques. Avrami analysis of crystal surface coverage was used to confirm one-dimensional transcrystalline growth commonly seen with SWNT nucleated crystals. Scanning electron microscopy was used to confirm shish-kebab structures present at the SWNT-polypropylene interface. The determined crystallization parameters were used on colloidal solutions of alumina platelets to successfully create uniformly coated particles with an improved interface. This method shows promise for improving the interphase of semicrystalline polymer-ceramic composites to achieve excellent material properties.