| Prepreg is composed of resin matrix and reinforcement. Resin matrix is used to impregnate the continuous fibers or fabrics under strictly controlled conditions, which results in the intermediate material for composite. As an intermediate material of composite material, the properties of the prepreg have a direct impact on the quality of the composites. It has an influence on the performance of composite molding process.In this paper, the storage aging behavior of the prepreg is conducted on the thermoset epoxy resin. The aging occurs slowly to cure during the time after production and before usage. Such curing behavior has disadvantages on the production and quality of the composites. It is critical to characterize the degree of aging and understand the influence on the final properties of the composites.In this paper, we prepare the prepreg materails by various aging time. The impact of aging on the flow properties of resin, enthalpy, resin content, volatile content and viscosity of the prepreg are investigated with many experiments, which gives out the influence of aging on the performance of the prepreg. It is found that with the increase of the aging time, the flow capability of the prepreg resin and the resin content is reduced, while the volatile content keeps almost constant. The tacky property of the prepreg reduces significantly, the enthalpy of the resin curing reaction increases with the increasing aging time.DSC(differential scanning calorimetry) testings, at the different heating speed,were conducted.According to the thermal analysis at the different heating cure of prepreg, the curing kinetics and curing parameters were investigated. The relationship between the degree of curing and curing time was established. And also, the relationship between the aging time and aging degree was studied.Based on the study on the aging characteristics of prepreg,prepregs at different aging time were used to produce composite laminates. Then the mechanical properties, such as bending, interlaminar shear and so on were tested. The effects of aging time on the mechanical properties of composite materials were studies. The results show that with the increase of the aging time, the bending properties of the composite began to decrease significantly at the starting point and keep constant after certain time of aging.With the increase of the aging time, the peak at internal friction of damping factor for composite Laminates reduces. The value of the peak occurs at higher temperature.The peak at internal friction of loss modulus reduce. The value of the peak also occurs at higher temperature.. The glass transition of storage modulus becomes short, but the initial temperature grows and the end temperature is substantially constant.It is used to setup the relationships between aging time and aging degree with the usage of the function of chemical reaction rate at different temperatures, Arrhenius equation, under the known aging conditions. It will give good instructions on the prediction of the prepreg quality after storage aging. |
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