Chemical Modification of Some Acrylic Polymers with Phosphorus-Containing Groups: Effects on Their Flame Retardance

Polymethyl methacrylate (PMMA) can undergo chain-stripping reactions to form a near quantitative yield of its monomer. On the other hand, polyacrylonitrile (PAN) upon decomposition can also form char residues, owing to the condensation of the pendant nitrile units, which in turn depends on the rate of heating. However, in both cases, low molecular weight volatiles once formed can subsequently undergo combustion reactions, and hence PMMA and PAN are considered to be relatively flammable. With a view to improving the flame retardance of these polymers, we have chemically modified them with phosphorus-, or optionally, phosphorus/nitrogen-containing groups. The recovered polymers, after necessary purification, were subjected to a host of characterization techniques that included spectroscopic, thermal and calorimetric tests. We have also endeavored to formulate the modes of action of the flame retardant groups, in the condensed and gaseous phases, occurring during the decomposition and combustion of these modified systems