Study Of Curing Behaviors Of Vinyl Ester Resin

X-158 vinyl ester resin(X-158VE) has excellent mechanical properties, chemical corrosion resistance and high temperature resistance of phenolic epoxy vinyl ester resin. To further enhance the X-158VE cured overall performance, it is necessary to study curing behavior and kinetics of the resin. methyl ethyl ketone peroxide (MEKP) is choiced as initiator. The curing behavior and curing reaction kinetics be related to curing agent are measured by means of DSC. The parameters of curing reactions are calculated. The best curing system and optimum curing conditions are determined as well. The effect of diluent is analyzed through viscidity test and infrared spectrum with Styrene (Vt) as the diluent of resin. Finally, the heat resistance is investigated by (TG-DSC) and the load heat distortion temperature meter (HDT).The results show that the MEKP is appropriate of 2-3wt%, and Vt is 3wt%. The least squares geltemperature(110.35°C), curing temperature (128°C) and temperature after curing treatment (161.3°C)are determined by fitting curves with different heating rates. With the isokinetic temperature, the ultimate degree of cure increases gradually, the curing time is reduced. Kissinger method and Ozawa method are used to determine the average apparent activation energy of 2.186×105J/mol, reaction order of 0.9604.The viscosity decreased with the increase of Vt. At room temperature, viscosity increases till a certain amount of Vt. Under the conditions of warming, Vt with contents of 3wt%, viscosity decrease gradually. At the moment, molecular diffusion is more uniform. It is found that a strong absorption band appeared at 3478cm-1in the infrared spectra, where is the hydroxyl stretching vibration absorption peaks, while 3735cm-1 is the hydrogen bonding hydroxyl stretching vibration absorption peak. The results indicate the process involved the reaction of Vt with water generated as well.When the content of Vt is 3wt%, HDT is much higher. With the Vt content increased, the HDT present a up-down trend. TG curve shows the thermal decomposition reaction is one step reaction. Furthermore, onset temperature and end temperature of thermal decomposition curing system are 341.9°C, 397.8°C, respectively, which indicate the material held well stability.