Thermal degradation of MWCNT/polypropylene nanocomposites: A comparison of TGA and laser pulse heating

Abstract

The kinetics of thermal degradation of isotactic polypropylene (PP) and PP with Multi-Walled Carbon Nanotubes (MWCNT) was studied using thermogravimetric analysis (TGA). Nanocomposites with 0.5, 1.0, and 2.0 wt % MWCNT showed enhanced thermal stability compared to the pure polymer. Higher heating rates showed a higher temperature for the 5% decomposition point and throughout the decomposition of the samples. This trend was seen at all heating rates ranging from 30 to 180 °C/min. The activation energy, calculated using the Flynn-Wall method, increased with the addition of the MWCNT, demonstrating that MWCNT contribute to the improved thermal stability of the polymer. In addition to TGA, the materials were examined at heating rates approximately 5 orders of magnitude higher than TGA with laser pulse heating. A TGA-analogue curve was constructed for the laser pulse heating case and the results were compared to traditional TGA. Laser irradiance and TGA heating rates exhibited similar effects, where higher heating rates showed lower mass loss than lower heating rates, in both regimes. MWCNTs were demonstrated to improve thermal stability in both the TGA and laser pulse heating experiments. In this work, we have established that there are similarities in nanocomposite thermal degradation behavior between the two regimes.