Comparative Study of the Effect of Different Nanoparticles on the Mechanical Properties, Permeability, and Thermal Degradation Mechanism of HDPE

In the present study, different series of high-density polyethylene (HDPE) nanocomposites were prepared by melt mixing on a Haake-Buchler Reomixer, containing 2.5 wt % of multiwall carbon nanotubes, pristine and modified montmorillonite, surface-treated and untreated SiO2 nanoparticles. From transmission electron micrographs, it was found that beyond a fine dispersion of nanoparticles into HDPE matrix, there are also some aggregates easily discriminated. As a result, there was a decrease in the tensile and impact strength of most of nanocomposites except Young's modulus, which was increased. Storage modulus as recorded from dynamic mechanical analysis was also increased in all nanocomposites, because HDPE becomes stiffer due to the incorporation of nanoparticles. The nucleation behavior of nanoparticles during crystallization was found to have no obvious effect on melting and crystallization temperature of HDPE. However, a small decrease in the heat of fusion in all nanocomposites was evidenced. Gas permeability of HDPE matrix in O-2, N-2, and CO2 was reduced in all nanocomposites compared with neat polymer. Thermal stability of HDPE was also enhanced due to the incorporation of different nanoparticles. From the kinetic analysis of thermal decomposition of HDPE, it was concluded that to describe the thermal degradation of HDPE and the studied nanocomposites, two consecutive mechanisms of nth-order autocatalysis have to be considered. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 1606-1618, 2009