Grafting of Phosphonate Monomer onto Natural Rubber Latexes via Emulsion Polymerization

The synthesis of phosphorus-containing monomer, methacryloyloxyethyl phenyl benzenephosphonate (MPBP), was carried out. The monomer was successfully prepared as evidenced by H-1 NMR, C-13 NMR, FT-IR and MS analyses. Subsequently, MPBP was grafted onto natural rubber particles via emulsion polymerization. It was found that as the reaction temperature increased from 40 to 70 degrees C, percent grafting efficiency increased from 72% to 85%. Transmission electron microscopy (TEM) of the grafted NR showed a semi core-shell morphology. Thermogravimetric analysis (TGA) of grafted NR indicated a two step degradation. Moreover, the grafted polyMPBP promoted the char residue of up to 3.5%. Flame tests revealed that the grafted NR exhibited an increased LOI value (20.5 %) over that of pure NR (17.0 %).