Substantial enhancement of PP random copolymer's thermal stability due to the addition of MWCNTs and nanodiamonds: Decomposition kinetics and mechanism study

• Polypropylene nanocomposites with MWCNTs and NDs exhibit superior thermal stability.
• MWCNTs enhance the stability of PPR more efficiently than NDs.
• Both fillers drastically modify in the degradation reactions and kinetics of PPR.

Polypropylene-random-copolymer (PPR) nanocomposites with multi-walled carbon nanotubes (MWCNTs) and nanodiamonds (NDs) in various concentrations were prepared in order to study the effects of the nanoparticles on the thermal behavior of PPR. From the thermogravimetric (TG) analysis it was found that MWCNTs lead to a more pronounce thermal stability enhancement compared to NDs. The higher specific surface area offered by the MWCNTs would lead to more nanoconfined polymer regions and hence, a superior thermal stability. A thermal stability enhancement was also caused when both of these fillers are incorporated into PPR in specific concentrations, yet a cumulative effect was not observed. The decomposition kinetics of all the synthesized nanocomposites was studied using two isoconversional methods along with the model-fitting method. The calculated kinetic parameters using both of these techniques are in agreement and they suggest that MWCNTs and NDs cause important differences in the decomposition process of PPR. Pyrolysis–gas chromatography–mass spectroscopy (Py–GC–MS) experiments confirmed the findings of thermogravimetric analysis as the modified decomposition reactions were revealed from differences in the evolving decomposition compounds, their distribution and total amount.