Nanocomposites and nanomaterials

Influence of carbon nanotubes content on the 
thermal-structural properties of high-density polyethylene

S. Khelil1, N. Barama1, T. Dorbani1, Y. Naoui1, M.C. Boulakleb1, 
S.G. Nedilko2, S. Revo2, S. Hamamda1

1 LTTSM, Mentouri Brothers Constantine 1 University, Algeria. 
E-mail: shamamda@yahoo.com
2 Taras Shevchenko National University of Kyiv, Institute of High Technologies, Volodymyrska St. 64/13, Kyiv 01601, Ukraine. 

This note aims at characterizing polyethylene-based nanocomposites containing different amounts of multiwall carbon nanotubes. The elaborated nanocomposites samples contained of 0, 0.1, 0.25, 0.5, 1.0, 2.5 and 5% MWCNTs. The studied materials were prepared using a high energy ball mill with a centrifugal force up to 50g. Several modern techniques such as dilatometry, calorimetry, mass loss, X-ray diffraction, infrared and Raman spectroscopy were used for investigation of the samples.
The calorific values of the studied samples changed with concentrations, thus, the PE+0.25%MWCNTS sample has the highest heating value. On the other hand, PE+0.1%MWCNTs was of the least intense. 
The content of the introduced MWCNTs plays a significant role in the mass loss of the samples. Their thermogravimetric curve changes little. This suggests that the insertion of the MWCNTs in the high-density polyethylene is the cause of the nanocomposites stability.  
The dilatometric measurements were made both in the radial and longitudinal directions. the longitudinal direction, they contain an anomaly around 50 – 55 °C and the curves overlap after 60 °C. In the radial direction, the expansion of PE+2.5%MWCNTs is higher than that of all other samples. It contains an intense anomaly located near 97 °C. The dilatometric curves of the other nanocomposites show very low expansion coefficients of the same order of magnitude. 
The Raman spectra of all samples have almost the same shapes. The D peaks are observable but the G peaks are undetectable. The infrared spectra change shape from one sample to another and the relative intensities of the peaks depend strongly on the concentration.
X-ray diffraction showed that the crystallites size are concentration dependent. On the other hand, there was a refinement of all the structures concerning that of the matrix.