Objective To improve the high temperature using performance of normal temperature curing epoxy resin system. Methods The normal temperature curing agent T31, the medium temperature curing agent IPDA and the high temperature curing agent DDM were used as the mixed curing agent for the normal temperature curing reaction of epoxy resin E-44 and AG-80 system, and to analyze influences of the environment temperature rising process on the thermody-namic performance. DMA analysis, thermal deformation measurement and curing degree test were taken to evaluate the changes of the glass transition temperature, the thermal deformation and the curing reaction in the epoxy resin system before and after the environment temperature rising process, respectively. The wet-heat resistance and the high tempera-ture mechanical properties of glass fiber reinforced the epoxy resin composites were studied through water absorption test and three-point bending test. Results The tgof normal temperature curing epoxy resin was 85.21 ℃ . After the heating process with average rate of 1.5 ℃ /min to 90℃ , the degree of cure increased to above 92%, the value of tgwas 132.06 ℃and the thermal deformation temperature ascended. The wet-heat resistance of the composites was improved and its bending strength retention was 65% at 100 ℃ . For the environment temperature rising process to 120℃ , the curing de-gree was close to 96%, the tgincreased to 144.45 ℃ and the thermal deformation temperature raised further. The im-provement on wet-heat resistance of the composites was more obvious and its bending strength retention remained close to 60% at 130 ℃ .Conclusion The mixed curing agent with rational matching including normal, medium, and high tem-perature curing agents helps to induce the curing gradient in the epoxy resin system under the condition of environment temperature increasing. During this process the degree of cross-linking in the system quickly rose to a higher level to im-prove the glass transition temperature and the thermodynamic performance at high temperatures of the room temperature curing epoxy resin significantly.%目的 提高常温固化环氧树脂体系的高温使用性能.方法 采用常温固化剂T31、中温固化剂IPDA以及高温固化剂DDM作为混合固化剂,对E-44型和AG-80型混合环氧树脂体系进行常温固化反应,并分析环境升温过程对固化物热力学性能的影响.通过DMA分析、热变形测量、固化度测试,分别评价室温固化环氧树脂在环境升温过程前后的玻璃化转变温度、热变形量及体系内部的固化反应程度变化,并通过吸水率测试和弯曲强度测试对玻璃纤维布增强常温固化环氧树脂基复合材料的耐湿热性能以及高温条件下的力学性能进行分析.结果 环氧树脂常温固化物的tg为85.21 ℃,经1.5℃ /min的平均升温速率加热至90 ℃之后,该环境升温过程使固化物的固化度增大至92%以上,tg增长为132.06 ℃的同时热变形温度增大.其复合材料耐湿热性能提高,且100 ℃时弯曲强度的保持率为65%,对于加热至120 ℃的环境升温过程,固化物的固化度接近96%,tg增长为144.45 ℃的同时热变形温度进一步提高,其复合材料耐湿热性能改善程度更加明显,且130 ℃时弯曲强度保持率仍接近60%.结论 常温、中温、高温混合固化剂的合理复配有助于环氧树脂体系在环境升温变化的诱导条件下发生梯度式固化反应,使体系内部的交联固化程度迅速升至较高水平,可以有效提高其玻璃化转变温度,显著改善常温固化环氧树脂体系在高温条件下的热力学性能.
展开▼
