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Title: A study of the thermal degradation of flexible TDI-based polyurethane foams
Author: Todd, Deborah
ISNI:       0000 0004 2743 954X
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2012
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A novel environmentally friendly fire retardant formulation for use in polyurethane foams has previously been developed at the University of Strathclyde; however, the fundamental chemistry relating to the fire retardancy of this foam was not well understood. The purpose of this research project was, therefore, to study the degradation behaviour of toluene diisocyanate (TDI)-based polyurethane foams in order to determine the mechanisms which occur and the effect that various fire retardants have on the degradation mechanisms. The results have demonstrated that the degradation of TDI-based polyurethane foam is a complex process consisting of different mechanisms which yield an array of volatile products and complex char residues. Degradation of the urethane linkages has been shown to occur by two competing mechanisms. The first involves depolymerisation of the urethane bond to yield TDI and polyol, whilst the second involves dissociation of the urethane linkages via a six- membered ring transition state to yield diaminotoluene (DAT), CO2 and alkene-terminated polyol chains. The results have shown that the dominant mechanism varies depending on the experimental conditions of the pyrolysis or degradation technique employed. Characterisation of the pyrolysis residues has demonstrated that complex aromatic chars are formed, with the structure dependent on the environment in which the pyrolysis is conducted. The addition of fire retardants adds to this complexity, making the understanding of the degradation processes a more complicated task. Ammonium polyphosphate (APP) has been shown to be an effective fire retardant, altering the degradation mechanisms of the foam and promoting char formation. The addition of vermiculite into the foam has been shown to have little effect on the fire retardancy when used alone. Cloisitea 30B, on the other hand, has been shown to have a detrimental effect, altering the degradation of the polyol such that copious quantities of propanal are evolved. This leads to the foam burning more readily.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available