Curing Kinetic Analysis and Isothermal Prediction of DBTL Catalyzed Polyurethane Reaction by Differential Scanning Calorimetry

Abstract

Kinetic analysis is generally carried out to clarify the reaction mechanism with kinetic parameters and to predict the kinetic properties of materials under different reaction parameters. The kinetics of the polyurethane polymerisation reaction between acrylic polyol and isocyanate was investigated by Differential Scanning Calorimetry (DSC) in terms of catalyst amounts and sampling times. Single and multiple heating analyses were used to obtain DSC curves for each sample. The simple kinetic model and Multilinear Regression Fit (MRF) were used to calculate the kinetic parameters and simulate the isotherm prediction curves. The kinetic calculations showed that the glass transition temperatures (up to 44 oC) and activation energy (Ea) values increased with the degree of conversion for all cases. The reduction in the rate constant for partially cured samples was greater than the initial sampling time of the same sample. This observation indicates that the diffusion-controlled reaction dominates and Ea increases due to the highly cross-linked and dense medium in partially cured samples. Isothermal prediction curves provide an understanding of different curing conditions at different reaction temperatures and times. Prediction curves show slower conversion even for final samples, confirming that final samples may remain uncured. Applying the results of this study, especially for real-world applications, where fully cured samples are required, additional annealing procedures can be easily established.