Pyro-GC/MS and thermal degradation studies in polystyrene-poly(vinyl chloride) blends

The blends of polystyrene (PS) using various proportions of poly(vinyl chloride) (PVC) were prepared and the thermal decomposition temperatures of these blends were measured from the dynamic thermogravimetric analysis (TGA) carried out under inert atmosphere from ambient to 800 degrees C at different heating rates. Kinetic parameters of the degradation process in pure PS and its blends with various proportions of PVC were calculated. Activation energy of the degradation process in the blends was found to increase with the inclusion of small amount of PVC in PS. The stabilization effect on PS varies with the heating rates and the composition of the blends. The pyrolysis gas-chromatographic mass spectrometry (Py-GC/MS) studies were also carried out over a range of temperature (330-370 degrees C) and the intensity of major ions produced during pyrolysis were separated and measured though GC/MS. Using a small amount of PVC in the matrix showed a marked reduction in the major pyrolysis products of PS. The stabilization of PS in the blends has been explained by a mechanism involving interaction between the degrading products from the polymer components leading to a stable polymer network. The extent of interaction is affected by the changing morphology of the blends with composition. (C) 2009 Elsevier B.V. All rights reserved.