Investigation of DSC curing kinetic model fitting and rheological behavior of urushiol/IPDI system

The curing behavior of urushiol/IPDI system was monitored by differential scanning calorimetry (DSC) and dynamic rheology. The change of activation energy during curing process was calculated by KAS, OFW and Friedman isoconversional methods. The relationship between curing reaction rate and temperature and curing degree was described by the piecewise fitting method. The results of model fitting and model-free fitting showed that the kinetic mechanism of the reaction changed from autocatalytic mechanism a<0.86 to n-order reaction mechanism a>0.86. The curing process of urushiol/IPDI was fitted by piecewise model, which was in good agreement with the experimental results. The piecewise model can accurately describe the curing process. The isothermal rheological test of urushiol/IPDI system was carried out. The results showed that the gelation time shortened with increasing temperature.