Kinetic analysis of the thermal degradation of polystyrene-montmorillonite nanocomposite

Nanocomposites exhibit a combination of unique properties, such as increased heat distortion temperature, reduced permeability, reduced flammability and improved mechanical properties. In this work, a polystyrene (PS) clay nanocomposite was prepared via bulk polymerization using a novel organically modified montmorillonite (MMT). The organic-modifier is the N,N-dimethyl-n-hexadecyl-(4-vinylbenzyl) ammonium chloride (VB16). The thermal stability of PS-VB16 compared to pure PS is examined in pyrolytic and thermo-oxidative conditions. It is then studied using a kinetic analysis. It is shown that the stability of PS is significantly increased in the presence of clay. The thermal behavior of PS and PS nanocomposite is modeled and simulated. A very good agreement between experimental and simulated curves both in dynamic and isothermal conditions is observed. Using kinetic analysis associated to the reaction to fire of PS nanocomposite simulated in a cone calorimeter, the peak of heat release rate is half that of virgin PS, it is suggested that the clay acts as a char promoter slowing down the degradation and providing a protective barrier to the nanocomposite. The combination of these two effects is an important factor lowering the HRR. (C) 2004 Elsevier Ltd. All rights reserved.