05 Mar Synthesis of new flame-retardants by radical chain transfer copolymerization of glycidyl methacrylate and dimethoxy-phosphorylmethyl methacrylate Back to Sci. Publications
R. Ménard, C. Negrell-Guirao, L. Ferry, R. Sonnier, G. David
European Polymer Journal, 57, 109-120
We present a new and original approach to prepare flame retardants (FR) compounds. The strategy adopted consists first in synthesizing new reactive phosphorus-containing oligomers and then to chemically graft them to an epoxy network. These reactive FR compounds are synthesized by radical chain transfer copolymerization of dimethoxy-phosphorylmethyl methacrylate (MAPC1) with glycidyl methacrylate (MAGLY). Reactivity ratios were determined rMAPC1 = 0.78 and rMAGLY = 1.28 at 80 °C. The molecular weight of all the (co)oligomers was calculated by steric exclusion chromatography between 1000 and 3000 g mol−1. The synthesized FR were incorporated into an epoxy matrix as reactive binders. Then these formulations were cured at high temperature and the cross-linking densities were determined by DSC. The thermal properties and burning behaviors of cured epoxy resins were investigated. Thermogravimetric analysis showed a small decrease in thermal stability accompanied by a 50% increase in char yield. Pyrolysis combustion flow calorimetry (PCFC) was also used to evaluate the flammability of the modified epoxy resin. A significant decrease in peak of heat release rate (pHRR) and total heat release (THR) was observed. Indeed, with 3%wP, the THR was reduced by 25% and the maximal heat release rate by 60% compared to the reference. These results demonstrate the good flame retardant properties of reactive oligomers in epoxy matrix.