EPOXY RESIN CURING REACTION STUDIED BY DYNAMIC AND ISOTHERMAL MODEL FREE KINETICS

The curing processes of bisphenol A epoxy resin E51/4,4'-diaminodiphenyl sulfone (DDS) and multi-functional epoxy resin AG80/DDS were studied using dynamic and isothermal model free kinetics (MFK) of Vyazovkin integral method based on DSC measurements. The MFK method from dynamic DSC data and the advanced MFK (AMFK) from isothermal DSC data were adopted to predict the evolution of curing degree and the relationship between activation energy and curing degree. Moreover, the curing reactions under dynamic and isothermal conditions were compared by the change of glass transition temperature and the experimental results of in situ infrared measuring method. The results show that comparing to traditional fitting model method, MFK is more suitable to predict quantitatively the curing process of epoxy resin and can provide important evidences for the study on the change of curing mechanism during curing reaction. Moreover,AMFK based on isothermal condition can predict the isothermal curing courses of two resin systems with higher accuracy. The relationships between reaction activation energy and the extent of cure obtained from dynamic and isothermal MFK are different, demonstrating that the curing mechanisms of two epoxy systems under different temperature conditions distinct. These results agree well with the vitrification effect and the evolution of epoxy group conversion under dynamic and isothermal conditions.