Placement tack and storage aging behavior of carbon fiber reinforced bismaleimide prepreg

The carbon fiber reinforced bismaleimide prepreg CCM40J/HT-280 was placed in different storage environments(vacuum, N₂, O₂, air)for room temperature aging experiments, and the relationship among the prepreg tack and storage environment and aging time was studied. The samples before and after the tack failure in different environments were analyzed by DSC, rheological and infrared spectroscopy. The CCM40J/HT-280 composites were prepared by autoclave molding process with the prepreg in different tack levels, and both the internal molding quality and mechanical properties of the composites were studied. The results show that the tack failure period of the CCM40J/HT-280 prepreg under the vacuum and N₂ storage environment is about 40% longer than that of the sample in O₂ and air.DSC and rheological test results show that the degree of crosslinking of the resin after aging is greater than that of virgin resin with the minimum viscosity significantly promoted, which is more obvious in the O₂ environment. The analysis of the characteristic peaks by infrared spectrum shows that the degree of crosslinking reaction of the resin in the O₂ environment storage is higher than that in the vacuum environment, indicating that O₂ promotes the aging of the bismaleimide resin at room temperature. The CCM40J/HT-280 composites prepared by the tack failure prepreg have dense pores inside or between layers, and the flexural strength of the composites decreases by about 13.0%, the flexural modulus decreases by about 6.5%, and the interlaminar shear strength decreases by about 10.7%.