Rheological Analysis And Low Defect Forming Mechanism During Curing Of Epoxy Resin

One of the keys to achieve a greater degree of weight reduction for advanced space vehicles is to reduce the weight of the fuel tank.The solution is to replace the metal-lined composite material tanks currently used with metal-free lining composite material tanks.However,the leakage problem of the all-composite storage tank is the primary problem that needs to be solved urgently,and the defect in the curing process is the main cause of the micro-crack leakage.Therefore,the control of the defect is very necessary.In this paper,research is carried out from curing kinetics,curing process parameter determination,rheology,etc.,in order to obtain a molding method capable of obtaining low defects.First,the theoretical pre-cure temperature,theoretical curing temperature,theoretical post-cure temperature,and thermal decomposition temperature of the AM-8927 A epoxy resin/AM-8927 B curing agent system were obtained by curing reaction kinetic analysis.The Kissinger equation and the Crane equation were used to obtain the pre-exponential factor,the apparent activation energy of the curing reaction,the number of reaction stages,and the kinetic equation of the stage solidification.Second,the theoretical parameters,rheological analysis and non-isothermal DSC method were used to obtain the curing process parameters of AM-8927 A epoxy resin/AM-8927 B curing agent system.The two-step curing system was used to determine AM-8927 A Epoxy resin / AM-8927 B curing agent system heating rate,low temperature step temperature,high temperature step temperature,the first curing step holding time,the second curing step holding time,and proposed in the first curing step insulation After completion,before the temperature rises to the temperature of the second curing step,the Parts is gradually heated by a gradient heating method.When the Parts is solidified,the temperature is lowered by means of furnace cooling to reduce the internal stress.At last,through the analysis of the rheological properties of AM-8927 A epoxy resin/AM-8927 B curing agent system,it is found that the addition of graphene oxide will affect the curing process of the curing system,and the addition of graphene oxide to the curing system,The effects of storage modulus,loss modulus,viscosity,and loss factor are not a simple linear relationship,but have different effects at different stages of the curing process.With the increase of graphene oxide content,the mechanical properties of AM-8927 epoxy resin curing system increased first and then decreased.Because of the increase in viscosity,the vacuum defoaming treatment is incomplete,and the internal quality of the sample tends to deteriorate as the graphene oxide content increases.