Thermal and mechanical properties of single-walled carbon nanotubes-polypropylene composites prepared by melt processing.

In this work well uniform dispersion of single-walled carbon nanotubes (SWNTs) in isotactic polypropylene (iPP) was achieved by shear mixing. The results obtained from the differential scanning calorimetry curves indicate that the addition of low SWNT amounts (less than 1 wt%) led to an increase in the rate of polymer crystallization with no substantial changes in the crystalline structure, as confirmed by X-ray diffraction. The tensile mechanical properties showed that Young_s modulus and tensile strength considerably increase in the presence of nanotubes, with a maximum for 0.75 wt%. The reinforcing effect of SWNTs was also confirmed by dynamic mechanical analysis where, by adding nanotubes, a noticeable increase in the storage modulus was detected. The beneficial effects of SWNT incorporation was underlined comparing the results obtained with those of carbon black used as a filler. 2005 Elsevier Ltd. All rights reserved.