A DETAILED ANALYSIS OF THE PYROLYSIS PRODUCTS FROM DIOCTYLTIN MALEATEAND ITS MIXTURE WITH PVC

The thermal decomposition of dioctyltin maleate (DOTM) and a blend of PVC and DOTM has been studied in air, nitrogen and under vacuum. TG wa s used to examine the effect of different amounts of DOTM on stability . The PVC/DOTM mixture shows delayed dehydrochlorination in both the a ir and inert environment compared with PVC. The blend shows more therm al stability in an inert atmosphere than in air. The decomposition pro ducts from a blend containing a high loading of DOTM were investigated using Thermal Volatilisation Analysis (TVA) and Subambient Thermal Vo latilisation Analysis (SATVA). Gas, liquid and tar fractions were sepa rated and analysed by IR spectroscopy, on-line mass spectrometry or GC -MS. High molecular weight polycyclic aromatic hydrocarbons (PAH) foun d in the pyrolysis of pure PVC were not found from the blend. The pyro lysis in the presence of air rather than inert atmosphere does not cha nge the nature of the products, although the relative amounts may be d ifferent. Traces of oxygen-containing volatile products are formed fro m the blend, while most of the oxygen-containing groups formed in the polymer pass into the tar as large fragments split from the crosslinke d network. Dioctytin dichloride is the most important product apart fr om HCl from the pyrolysis of the PVC/DOTM mixture. (C) 1998 Elsevier S cience Limited. All rights reserved.