The effect of clay type and of clay-masterbatch product in the preparation of polypropylene/clay nanocomposites

摘要

Clay containing polypropylene (PP) nanocomposites were prepared by direct melt mixing in a twin screw extruder using different types of organo-modified montmorillonite (Cloisite 15 and Cloisite 20) and two masterbatch products, one based on pre-exfoliated clays (Nanofil SE 3000) and another one based on clay-polyolefin resin (Nanomax-PP). Maleic anhydride-grafted polypropylene (PP-g-MA) was used as a coupling agent to improve the dispersability of organo-modified clays. The effect of clay type and clay-masterbatch product on the clay exfoliation and nanocomposite properties was investigated. The effect of PP-g-MA concentration was also considered. Composite morphologies were characterized by X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM), and transmission electron microscopy (TEM). The degree of dispersion of organo-modified clay increased with the PP-g-MA content. The thermal and mechanical properties were not affected by organo-modified clay type, although the masterbatch products did have a significant influence on thermal and mechanical properties of nanocomposites. Intercalation/exfoliation was not achieved in the Nanofil SE 3000 composite. This masterbatch product has intercalants, whose initial decomposition temperature is lower than the processing temperature (T ～ 180°C), indicating that their stability decreased during the process. The Nanomax-PP composite showed higher thermal and flexural properties than pure PP.