Study of the degradation of fire-retarded PP/PE copolymers using DTA/TGA coupled with FTIR

A PP/PE copolymer was successively flame retarded using Mg(OH)(2), then usi ng brominated trimethylphenyl indane associated with Sb2O3 (Br/Sb), and fin ally using blends of equal weights of this last combination with Mg(OH)(2) or talc-containing non-hydrated fillers. Decompositions of pure and additiv e-containing copolymer were studied by DTA/TGA coupled with FTIR. A good co rrelation exists between the maxima of Gram-Schmidt curves and the derivati ves of TGA curves. The coupling of techniques shows that the incorporation of the Br/Sb flame retardant limits strong exothermic phenomena due to samp le ignition. In the case of Mg(OH)(2) associated with Br/Sb, the decomposit ion of the hydrated mineral occurs at a lower temperature than the reaction between brominated trimethylphenyl indane and Sb2O3. This delays the actio n of Br/Sb flame retardant towards higher temperatures, improving the therm al stability of the polymer. A good agreement is also found between DTA/TGA -FTIR conclusions and fire resistance tests carried out on standardized sam ples. When magnesium hydroxide is replaced by the fillers, the interest in using a purr talc, which appeared in fire resistance tests, is not strongly confirmed by DTA/TGA-FTIR. This discrepancy may be ascribed to the reduced influence of mass diffusion phenomena due to the small weight of the sampl e used in thermal analysis experiments. (C) 2000 Elsevier Science Ltd. All rights reserved.