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Title: A mechanistic study into the flame retardant and smoke supressant properties of molybdenum trioxide in brominated polyester thermosets
Author: Lever, T. J.
ISNI:       0000 0001 3608 606X
Awarding Body: Council for National Academic Awards
Current Institution: Kingston University
Date of Award: 1982
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The use of molybdenum trioxide as a smoke suppressant and flame retardant in bromine-containing polyester thermosets has been studied. Oxygen index studies showed that Mo03 has a synergistic flame retardant effect when incorporated into the brominated polyester resins. During flaming combustion, polymers containing Mo03 produced less smoke and more char. Thermogravimetric studies indicated that the inclusion of Mo0 in the polymer affected its degradation profile. The Mo0 3 3 was found to have no effect on the first of the three observed weigfit loss steps, which appeared to be due to the loss of phthalic anhydride from the resin. Changes were observed in the temperatures and weight losses of both of the subsequent degradation steps. Again it was found to increase the char levels and lower the temperature of char oxidation. No transfer of molybdenum to the vapour phase was observed, no evidence being found for the formation of a volatile molybdenum halide on oxy-halide. MoO was recovered practically quantitatively after polymer degra~ation in air, although in nitrogen it ended up as the carbide. Further evidence for the condensed phase mechanism was found in nitrous oxide index studies of the polyester where the index increased in the presence of Mo03• Changes were observed in both the condensed and vapour phase degradation products in the presence of Mo03• Elemental analysis of the solid residues remaining after heating the polymer formulations showed that Mo03 accelerated the loss of halogen to the vapour phase. This effect is thought to be responsible for the flame retardant activity of Mo03. Inclusion of MoO into the polyesters resulted in a change in the ratio of aroma~ic to aliphatic degradation products. Overall the quantity of aromatics evolved was reduced. Since these are the precursors of smoke in flaming combustion, their attenuation could account for the smoke reduction properties of Mo03 in the presence of bromine.
Supervisor: Not available Sponsor: Royal Borough of Kingston upon Thames
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Chemistry, general