The aim of this thesis was to study the reaction kinetics of uncatalyzed and catalyzed polyurethane systems. The isocyanate of choice to study the reaction was an isomeric mixture of methylene diphenyl diisocyanate (MDI). The MDI consisted of 63 wt% of 4,4’-MDI and 37 % of 2,4-MDI, going by the name suprasec 3030 supplied by Huntsman. The poly-ol used to study the reaction was polypropylene glycol with an average molar mass of 425 g/mol. This selection satisfied the condition that both catalyzed as uncatalyzed system can be modelled with the same materials under similar conditions. The tertiary amine used as a catalyst in this study was DABCO. Differential scanning calorimetry and microcalorimetry experiments were conducted to obtain experimental heat flow. First a method was developed to obtain reproducible experiments in both instruments. Second, for isothermal experiments the data collection range from isothermal microcalorimetry (TAM-III) has been extended by combining it with data obtained from the Discovery DSC. This was necessary considering that a significant amount of reaction heat is lost during the stabilization of the TAM-III microcalorimeter, especially for catalytic experiments. Isothermal data was gathered at 25 C and 40 C for three stoichiometries of mixtures. These experiments were then repeated for four different catalyst concentrations to gain a good isothermal data set. Non-isothermal experiments were conducted to see the influence of catalyst over a temperature range and to expand the data set further. In a final phase, a mechanism was proposed to model the experimental kinetic data obtained. The first optimization was successful for the isothermal data at 40 °C for the catalyzed experiments. This might be an indication that the proposed model is applicable on catalyzed polyurethane systems.
|6 sep 2018
- Vrije Universiteit Brussel
|Guy Van Assche (Promotor) & Robrecht René Verhelle (Advisor)