Polymer nanocomposites based on needle-like sepiolite clays: Effect of functionalized polymers an the dispersion of nanofiller, crystallinity, and mechanical properties

Polypropylene (PP)/sepiolite (Sep) nanocomposites are prepared by melt compounding in a mini-extruder apparatus. The often used maleic anhydride-modified polypropylene (PP-g-MA) is compared with two custom-made functionalized polymers, PP-acid and the di-block copolymer PP-PEO, with respect to the filler dispersion and filler reinforcement efficiency. For that purpose, morphological and mechanical studies are carried out by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and mechanical tensile tests. In addition, the nanocomposites are characterized by wide-angle X-ray scattering (WAxS) and differential scanning calorimetric (DSC) techniques, to assess the effect of the nanofiller on the crystalline structure of the PP matrix nano-filler. The use of PP-PEO and PP-acid resulted in a better nanofitler dispersion compared with traditional PP-g-MA-modified systems. Sepiolite acts as nucleating agent for the crystallization of PP and seems to lead to an orientation of the a-phase crystals. (C) 2007 Wiley Periodicals, Inc.