Pyrolysis study of a phosphorus-containing aliphatic-aromatic polyester and its nanocomposites with layered silicates

This paper deals with the thermal decomposition behaviour of a new fire retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-containing aliphatic-aromatic polyester and its nanocomposites with natural layered silicate (montmorillonite) under inert atmosphere studied by TGA-FTIR, Pyrolysis-GC/MS of volatile products and ATR-FTIR of non-volatile decomposition products. The phosphorus-containing polyester undergoes decomposition in two steps between 340 and 516 °C. The first step is associated with the release of carbon dioxide, acetaldehyde, ethene, acid-containing products (mainly benzoic acid) resulting in the formation of polyarylates followed by their decomposition in the second step with the evolution of carbon dioxide. DOPO-containing products, esters (mainly diethenyl terephthalate), carbon monoxide, acids and water are released through both stages. At the end of decomposition polyaromatic structures, diarylketones and organophosphorus esters built into the chemical structure of the char develop in the solid residue. The modification of the polyester with a layered silicate does not change the composition of the pyrolysis products, only their yield, and tended to diminish the charring of the polymer. A thermal decomposition scheme of the P-polyester is proposed and the mass spectra of some DOPO-containing products are discussed.