PREDICTION OF THE MECHANICAL-PROPERTIES OF A CROSS-LINKING POLYMER FROM A COMBINATION OF THE MEASURED KINETICS AND A MODEL FOR NETWORK GROWTH

The mechanical properties of a crosslinking isocyanate-hydroxy system were predicted by a combination of the measured curing kinetics and a model for polymer network growth. The kinetic parameters were determined from FTIR using the linear rising temperature method (the activation energy = 52 kJ/mol, reaction order = 2.9). This data, combined with the network model, was used to predict the rise in elastic modulus as measured by dynamic mechanical analysis (DMA). The agreement between the predicted and experimental results was excellent over the early part of the curing, but the model failed at higher isocyanate conversions. In addition a novel method for obtaining the activation energy for the reaction directly from DMA results is presented; the value obtained from this method was in excellent agreement with that obtained by FTIR.