Curing kinetics of block copolymerization thermoset polyurethane by non-isothermal DSC method

Polyurethanes consist of hard and soft segments, with the hard segments typically comprising blocks containing isocyanate groups, while the soft segments often consist of chains terminated with hydroxyl groups. The hard segments contribute to the mechanical properties of polyurethanes, while the soft segments provide elasticity and flexibility. The essence of curing lies in the mixing of hard and soft segments and subjecting the system to high temperatures. The curing kinetics of PEG/PCL/IPDI/N100 in-situ block copolymers were investigated using dynamic isothermal differential scanning calorimetry (DSC). Key curing parameters were obtained from non-isothermal DSC curves, and these parameters were incorporated into an n-order reaction model to determine the reaction type and apparent activation energy, thus deriving the reaction equation. The curing kinetics of PEG/PCL/IPDI/N100 in-situ block copolymers follows an n-th order autocatalytic reaction, where n is 1, and the activation energy is approximately 52.79 kJ/mol. Based on the reaction equation, the curing process conditions, namely the initial curing temperature (T-i), the peak exothermic temperature (T-p), and the finishing temperature (T-f), were deduced. Studying the curing kinetics of thermosetting polyurethanes can deepen our understanding of the interactions and reaction mechanisms between reactants under different conditions, thereby enhancing our grasp of the curing process. Furthermore, research into curing kinetics can provide a basis for optimizing preparation processes.