Objective To guarantee structural integrity and use safety of composites, and study hydrothermal behaviors, macroscopic mechanical properties and physical behaviors of resin matrix composites in hygrothermal environment. Methods Hydrothermal aging behaviors of T300/QY8911 composites at high temperature were studied through the ac-celerated aging method. Change rules of glass-transition temperature and mechanics performance of composites under different hydrothermal conditions were studied by dynamic mechanical thermal analysis (DMTA) and the mechanical property test respectively. Results The moisture absorption change of T300/QY8911 composites followed the Fick's se-cond law in the initial stage of hydrothermal treatment. The glass-transition temperature (θg) of T300/QY8911 composites decreased with the increase of moisture absorption. The Tg of T300/QY8911 composites corresponding to the tgδ peak decreased greatly under the saturated moisture absorption conditions. Tensile strength and compression strength of com-posites also decreased with the increase of hydrothermal treatment time. Conditions of hydrothermal treatment had ob-vious effect on the tensile fracture macro morphology of composites but have less effect on the compress fracture macro morphology of composites. Conclusion T300/QY8911 composites reach the saturated moisture absorption statue after 432 hours; the saturated moisture absorption is 1.34%; the diffusion coefficient of water molecule in composites is 7.38×10-5 mm2/s and the moisture absorption rate is 1.29×10-2s-1. Under saturated moisture absorption conditions, the θgof T300/QY8911 composites corresponding to the tan δ peak decreases by 59.2 ℃ than dry state. The tensile strength and compression strength of T300/QY8911 composites decrease by 16.2% and 0.6% respectively than that of the nature state.%目的 为保证复合材料结构的完整性和使用安全,对树脂基复合材料的湿热行为、湿热环境下的宏观力学性能和物理行为进行研究.方法 采用加速老化法,在高温下对T300/QY8911复合材料进行湿热老化行为的研究.借助动态力学热分析(DMTA)、力学性能测试研究湿热条件下的玻璃化转变温度和力学性能的变化规律.结果 T300/QY8911复合材料吸湿率的变化在湿热处理初期符合 Fick 第二定律, T300/QY8911复合材料的玻璃化转变温度均随着复合材料吸湿率的增加呈下降趋势,在饱和吸湿条件下tan δ 峰对应的 θg值具有较大的下降幅度,复合材料的拉伸强度和压缩强度均随着湿热处理时间的增加而出现下降,湿热处理条件对复合材料拉伸断裂宏观形貌的影响比较明显,而对复合材料压缩断裂宏观形貌的影响较小.结论 T300/QY8911复合材料在432 h到达饱和吸湿,饱和吸湿率为 1.34%,水分子在复合材料中的扩散系数为7.38×10-5mm2/s,吸湿速率为1.29×10-2s-1,饱和吸湿条件下T300/QY8911复合材料的θg下降了59.2 ℃.T300/QY8911 复合材料拉伸强度的下降幅度为 16.2%,压缩强度的下降幅度为 0.6%.
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