Curing kinetics of a rigid polyurethane foam formulation |
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Authors: | Jorge H. Marciano Alfredo J. Rojas Roberto J.J. Williams |
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Affiliation: | Department of Chemical Engineering, University of Mar del Plata, Juan B. Justo 4302, (7600) Mar del Plata, Argentina |
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Abstract: | The curing kinetics of a typical commercial formulation used in the manufacture of rigid polyurethane foams has been studied. The adiabatic temperature rise method was used, taking into account corrections for heat losses. A polymeric isocyanate was reacted with a stoichiometric amount of a polyether polyol, using dibutyltin dilaurate (DBTDL) as catalyst. For DBTDL < 2.6 mol m?3, a strong inhibition of the catalyst took place, and the uncatalysed reaction played a major role. Second order kinetics gave a good fit for the whole conversion range. For DBTDL > 2.6 mol m?3, the catalysed reaction took place. Second order kinetics were applicable up to the gel point, but then the rate slowed down severely. A first order dependence on the initial catalyst concentration was observed in the pre-gel region. The kinetics are discussed in terms of a modified version of the Van der Weij's mechanism. The heat of reaction was 17.6 kcal/NCO equivalent. |
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Keywords: | Polyurethane kinetics polyurethane foams polyurethane reaction mechanism polyurethane curing adiabatic temperature rise |
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