Synthesis and thermal behavior of a novel UV-curable transparent flame retardant film and phosphorus-nitrogen synergism of flame retardancy

A novel phosphorus monomer (PDHA) has been synthesized through phenyl dichlorophosphate (PDPC) reacting with 2-hydroxyethyl acrylate (HEA). The structure of PDHA was characterized by Fourier transform infrared spectroscopy (FTIR) and H-1 nuclear magnetic resonance spectroscopy (H-1 NMR). A series of UV curable resins were manufactured by blending PDHA with triglycidyl isocyanurate acrylate (TGICA) at different weight ratios. The fire performance was examined by micro-scale combustion calorimeter (MCC) and limiting oxygen index (LOI). The results obtained from MCC indicated that the addition of PDHA to TGICA reduced the HRR and HRC. In addition, the LOI values varied from 28 to 34. The char residues of the composites were observed by scanning electron microscopy (SEM). Their thermal degradation behavior was investigated by thermogravimetric analysis and real time FTIR analysis (RT-FTIR). The test results indicated that when the weight ratio of PDHA/TGIC - 1:1, the onset temperature of the composite was highest and the most char residue at 700 degrees C was observed. RT-FTIR showed that the phosphate group of PDHA first degraded to form poly(phosphoric acid)s at around 300 degrees C, which had the major contribution to form the compact char to protect the sample from further degradation. Copyright (C) 2010 John Wiley & Sons, Ltd.