The Role of Decomposition Temperature for Flame Redartancy Mode of Action in the Condensed Phase
- Condensed-phase mechanisms play a major role in fire-retardant polymers. Generations of development have followed the concept of charring to improve fire properties. Whereas the principal reactions are believed to be known, the specific description for multicomponent systems is lacking, as is the picture across different systems. One important aspect in achieving, adjusting and optimising flame retardancy in the condensed phase is exploiting chemical reactions between the pyrolysing polymer and flame retardant at the right place, time and temperature. It is the aim of this contribution to address the role of the decomposition temperature of both flame retardant and polymer by the means of two examples: First, aryl phosphates in Polycarbonate/ Acrylonitrile-Butadiene-Styrene (PC/ABS) blends, where the reaction with the early stage decomposition products of PC is controlling the flame retardancy mechanism in the condensed phase. Second, a comprehensive set of phosphorus flame retardantsCondensed-phase mechanisms play a major role in fire-retardant polymers. Generations of development have followed the concept of charring to improve fire properties. Whereas the principal reactions are believed to be known, the specific description for multicomponent systems is lacking, as is the picture across different systems. One important aspect in achieving, adjusting and optimising flame retardancy in the condensed phase is exploiting chemical reactions between the pyrolysing polymer and flame retardant at the right place, time and temperature. It is the aim of this contribution to address the role of the decomposition temperature of both flame retardant and polymer by the means of two examples: First, aryl phosphates in Polycarbonate/ Acrylonitrile-Butadiene-Styrene (PC/ABS) blends, where the reaction with the early stage decomposition products of PC is controlling the flame retardancy mechanism in the condensed phase. Second, a comprehensive set of phosphorus flame retardants in thermosets and their corresponding carbon fibre reinforced composites based on two different epoxy systems. Both examples show that key reactions between intermediate decomposition products only occur when the decomposition temperature ranges correspond to each other. The systems can be shifted towards condensed phase activity such as charring or inorganic glass formation as well as towards phosphorus release and thus flame inhibition in the gas phase. Changing the role of flame retardancy mechanisms also influence the efficiency in the achieved flame retardancy.…