The hygrothermal aging test of T800 carbon fiber/epoxy resin composites was carried out. Through mass change, surface morphology before and after aging, dynamic mechanical properties, infrared spectroscopy, interlayer shear and compression tests, the effects of solution immersion in deionized water and 3.5% (mass fraction, the same as below) NaCl solution at 70℃ on the mechanical properties of carbon fiber/epoxy resin composites were studied. The results show that the moisture absorption rate of T800 carbon fiber/epoxy resin matrix composite is relatively low in deionized water and 3.5%NaCl solution, which is 0.82% and 0.67%, respectively; Good adhesion between unaging sample fiber and matrix, after aging in 3.5%NaCl solution, the interface damage between fiber and matrix is more serious than that in deionized water. After immersion in deionized water, the shear strength is decreased by 8.8%, the compressive strength is decreased by 4.3%. After soaking in 3.5% NaCl, the shear strength is decrease by 10.1%, the compressive strength is decreased by 4.7%. The Tg of the samples decreased after aging in the two solutions, but the difference is not significant, at the same time, no new substances are generated or chemical reactions occur. The research results provide a basis for the application of T800 carbon fiber/epoxy resin composites in corrosive environment.
Fig.2 不同浸泡溶液下SEM照片 (a)未老化;(b)去离子水老化30 d;(c)3.5%NaCl溶液老化30 d
Soaking solution
Maximum damage load/N
Shear strength/MPa
Unaged
4875
76.781
Pure water
4448
70.056
3.5%NaCl
4385
69.064
Table 1 不同溶液浸泡对T800碳纤维复合材料层间剪切性能的影响
Soaking solution
Maximum damage load/N
Compression strength/MPa
Unaged
33251
604.425
Pure water
31806
578.158
3.5%NaCl
31682
575.904
Table 2 不同溶液浸泡对T800碳纤维复合材料压缩性能的影响
Fig.3 不同环境下的DMA曲线
Fig.4 老化前后红外光谱图
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