New developments and trends in phosphorus flame retardants

摘要

@@This paper reviews trends in the development of new commercial phosphorus-based flame retardants(FRs) for polymeric materials. Historically phosphorus-based flame retardants were mostly used in highly charrable polymers originally with natural cellulosic materials. In such polymers inorganic phosphates or phosphate esters can esterify or transesterify the polymer at high temperature and then the phosphorylated polymer produces char at the expense of fuel. This is a main basis of the condensed phase mechanism of flame retardant action of phosphorus flame retardants. However, it was also noted for many years that phosphorus-based moieties are very efficient free radical scavengers in the flame. In contrast to halogens which easily volatilize to the flame as hydrogen halides, phosphorus based FRs tend to decompose to phosphoric acid moieties and stay in the condensed phase. The gas phase efficiency of phosphorus flame retardants was usually underutilized.