Han Ruiyan, Ma Xiaoyan, Cai Lifeng, Zhang Zongwu, Fang Yiliang, Wang Jian
School of Chemistry and Chemical Engineering, Northwestern Polytechnical University Xi'an 710072 PR China
RSC Adv. 2024 Mar 1;14(11):7263-7275. doi: 10.1039/d3ra08390j. eCollection 2024 Feb 29.
The mechanical and high-temperature resistance properties of epoxy resins cured at low temperatures ( ≤ 100 °C) are often inferior, and the most toughening modification methods for epoxy resins tend to compromise thermal resistance, which significantly limit the practical applications of it. Therefore, this work reported a low viscosity and low-temperature curing epoxy hybrid resin system (OPEP), adopting E-51 as a resin matrix, liquid anhydride (MHHPA) as a curing agent, tertiary amine (DMBA) as a curing accelerator, and reactive octa-epoxy terminated polyhedral oligomeric silsesquioxane (OG-POSS) as a toughening modifier. Results demonstrated that the OPEP system has excellent processability with low viscosity and long processing window period and satisfies the practical requirements of low-temperature curing. The OG-POSS exhibits superior compatibility and reactivity with the resin matrix, and its addition slightly reduces the of the curing reaction and has a certain promotive effect on the curing of epoxy resin. In addition, the curing reaction rate of the OPEP resin complies with the Šesták-Berggren autocatalytic kinetics model. The impact strength, flexural strength, tensile strength, and elongation at break of the OPEP resin reached a maximum of 15.55 kJ m, 121.65 MPa, 90.36 MPa, and 2.48%, representing increases of 55.97%, 3.1%, 64.68%, and 26.51% compared to those of the pure resin, respectively. Notably, due to the heat-resistant inorganic silicon cage structure of OG-POSS, the thermal decomposition temperature (), glass transition temperature (), and heat distortion temperature () of the OPEP resin were 313.2 °C, 123.7 °C, and 102.0 °C, showing increases of 13.0 °C, 2.3 °C, and 6.8 °C compared to the pure resin, respectively, which is difficult to achieve for the general thermosetting resin toughening modification method. This research utilized organic-inorganic nanohybrid materials (POSS) to optimize the toughness and thermal stability of the resin in a coordinated manner, providing guidance for the preparation of high-performance epoxy resins that cure at low temperatures.
低温（≤100℃）固化的环氧树脂的机械性能和耐高温性能往往较差，而环氧树脂最常用的增韧改性方法往往会牺牲耐热性，这显著限制了其实际应用。因此，本研究报道了一种低粘度、低温固化的环氧杂化树脂体系（OPEP），采用E-51作为树脂基体，液态酸酐（MHHPA）作为固化剂，叔胺（DMBA）作为固化促进剂，以及反应性八环氧端基多面体低聚倍半硅氧烷（OG-POSS）作为增韧改性剂。结果表明，OPEP体系具有优异的加工性能，粘度低，加工窗口周期长，满足低温固化的实际要求。OG-POSS与树脂基体表现出优异的相容性和反应活性，其加入略微降低了固化反应的活化能，对环氧树脂的固化有一定的促进作用。此外，OPEP树脂的固化反应速率符合Šesták-Berggren自催化动力学模型。OPEP树脂的冲击强度、弯曲强度、拉伸强度和断裂伸长率分别达到最大值15.55 kJ/m²、121.65 MPa、90.36 MPa和2.48%，与纯树脂相比分别提高了55.97%、3.1%、64.68%和26.51%。值得注意的是，由于OG-POSS的耐热无机硅笼状结构，OPEP树脂的热分解温度（Td）、玻璃化转变温度（Tg）和热变形温度（HDT）分别为313.2℃、123.7℃和102.0℃，与纯树脂相比分别提高了13.0℃、2.3℃和6.8℃，这对于一般的热固性树脂增韧改性方法来说是难以实现的。本研究利用有机-无机纳米杂化材料（POSS）协同优化了树脂的韧性和热稳定性，为制备低温固化的高性能环氧树脂提供了指导。
