Citation

Green J. J. Fire Sci. 1994; 12(6): 551-581.

Copyright

(Copyright © 1994, SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Bromine and phosphorus were shown to be synergistic in flame retarding a polycarbonate/PET blend as measured by oxygen index. This synergy is enhanced when both elements are present in the same molecule. Cone calorimeter data confirm these observations. Chars were formed by pyrolysis in the TGA apparatus, by burning at high oxygen concentration in the oxygen index apparatus and by forced combustion in the cone calorimeter. Chars formed from the polymer blend containing the brominated phosphate gave 40-50% more char by weight than when bromine, phosphorus or blends of the two were used. Analyses of the chars showed no bromine and considerable phosphorus. TGA and DSC studies suggest that the polycarbonate and the PET undergo transesterification during pyrolysis above 400-degrees-C and the brominated phosphate acts as a transesterification inhibitor or stabilizer. SEM of the chars showed a considerable difference. When the brominated phosphate was used the char had a fine porous structure and thick solid skin. The other chars showed poorer structure and less to no skin. Measurement of the properties of the chars showed the char from the polymer containing the brominated phosphate to have a creep modulus 35 times greater than the char obtained from the polymer containing the bromine flame retardant.