On-line Monitoring The Curing Behavior And Kinetics Of Resin By Ultrasonic Technique

The application of composite materials has shown an impressive increase. However,their excellent performance depends primarily on the matrix resin.The study of curing process of matrix resin has become the focus in the field.So,it is important to develop non-invasive,in-situ and real time tools to monitor resin curing to enable an accurate determination of the curing process and enhance the quality of composite material.In this study,ultrasonic wave propagation has been applied to monitoring of the curing reaction progresses of epoxy and vinyl ester resins.At the same time,Differential Scanning Calorimetry(DSC)was used to study the curing kinetics of the resins.Non-invasive ultrasonic transmission technique was demonstrated to detect the curing of epoxy and vinyl ester resins.Results show that there is a good relationship between the ultrasonic transmission signals and the curing reactions of resins.The ultrasonic technique is capable to quantify the critical stages including gelation and vitrification during the cross-linking processes.The changes of attenuations and shear modulus with the curing time can be obtained from the velocities of longitudinal and shear waves measured.Moreover,ultrasonic techniques can measure and distinguish the different curing processes under the different cure conditions such as mold thickness,curing agent proportion and curing temperature.Furthermore,DSC has been applied to study the curing kinetics of epoxy and vinyl ester resin.Results show that the activation energy of epoxy is 55.75kJ/mol.The reaction order is 0.9.It indicates that the curing reaction is complicated.The appropriate curing reaction temperature of epoxy resin is from 44℃to 75℃,and then to 140℃for a period time.The activation energy of vinyl ester resin obtained is 46.38kJ/mol.The reaction order of vinyl ester resin is 0.89.Its appropriate curing reaction temperature is from 49℃to 75℃,and then to 139℃.In addition,the reaction degree of vinyl ester resin was measured by ultrasonic techniques and DSC, respectively.In short,the ultrasonic technique as a non-invasive,in-situ and real time tool is valuable in the study of the curing process and its kinetics of matrix resin.