Enhancing Fire Retardance of Styrenic Polymers Through a Ter-Polymerization Route

Polystyrene was chemically modified with selected organic phosphonates and N-containing unsaturated compounds (Figure 1) via ter-polymerization. The successful incorporation of P and N monomeric units was confirmed by 1H and 31P NMR spectroscopy. Thermal decomposition and combustion of the prepared ter-polymers were studied using Thermo-Gravimetric Analysis (TGA), Pyrolysis Combustion Flow Calorimetry (PCFC) and Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). The thermal stability and combustion characteristics of the modified styrenic polymers were significantly altered when nominal amounts of P- and N- containing groups were integrated into the polymeric chains. In certain cases, synergism of these groups was evident. For instance, as revealed by TGA, an extent of char formation, particularly under the oxidative atmosphere, was enhanced by more than 40% as compared to the unmodified polystyrene. For some ter-polymers, heat release rates and heat release capacities of the ter-polymers, measured through PCFC, were almost halved compared to similar parameters of the unmodified counterpart.


Figure 1. Chemical structures of P- and N-containing monomers used for ter-polymerization.