Preparation of Novel Pyrazole Cyclic Polymer/Montmorillonite Nanocomposites and Their Thermal Decomposition Kinetics

Abstract

In present work, a series of novel pyrazole cyclic polymer poly(1,3-diphenyl-1H-pyrazol-5-yl methacrylate)/montmorillonite based nanocomposites, [poly(DPMA/OMMT : 2-7wt%) were prepared by in situ polymerization technique. Organic-modifier was vinylbenzyldimethylhexadecyl ammonium chloride. The X-ray diffraction analysis (XRD) showed that the clay dispersion in the polymer matrix was exfoliated type for all nanocomposites. A positive change was observed between the reinforced clay ratio and the thermal stability of the nanocomposites from thermogravimetry (TGA). It was determined that the nanocomposite with 7 wt % clay content was approximately 34.9°C more thermally stable than the undoped polymer. Thermal kinetic analysis of the decomposition process of nanocomposites in a conversion range of 7–19% was evaluated from dynamic experiments by means of various kinetic models such Flynn–Wall–Ozawa, Kissinger, Coats–Redfern, Tang and Madhusudanan methods. Doping the organoclay into the pyrazole polymer increased the activation energy from 79.5 to 109.5 kJ/mol compared to pure polymer. The results obtained from kinetic methods showed that all nanocomposites proceed via the thermal decomposition mechanism, D₁, one-dimensional diffusion type deceleration mechanism.