Yu Qian, Liang Yeyun, Cheng Juan, Chen Sufang, Zhang Aiqing, Miao Menghe, Zhang Daohong
Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission & Ministry of Education, South-Central University for Nationalities, Wuhan, Hubei 430074, China.
Key Laboratory for Green Chemical Process of Ministry of Education, Wuhan Institute of Technology, Wuhan, Hubei 430073, China.
ACS Omega. 2017 Apr 7;2(4):1350-1359. doi: 10.1021/acsomega.7b00132. eCollection 2017 Apr 30.
Degradation and recycling of cured thermosetting epoxy resins are major challenges to the industry. Here, a low-viscosity, degradable epoxy-ended hyperbranched polyester (DEHP) is synthesized by a reaction between epichlorohydrin and a carboxyl-ended hyperbranched polyester (DCHP) obtained from an esterification between citric acid and maleic anhydride. The chemical structures of DCHP and DEHP were characterized by Fourier transform infrared and H NMR. DEHP has a positive effect on reinforcing and toughening of the diglycidyl ether of bisphenol-A (DGEBA). With an increase in the content and molecular weight of DEHP, the mechanical performances of the cured DEHP/DGEBA composites, including the tensile, flexural, and impact strengths, increase first and then decrease. The improvements on the tensile, flexural, and impact strengths were 34.2-43.4%, 35.6-48.1%, and 117.9-137.8%, respectively. Moreover, the DEHP also promotes degradation of the cured DEHP/DGEBA composites. The degree of degradation of the cured DEHP/DGEBA composites increases with an increase of the DEHP content and molecular weight. The composites containing 12 wt % DEHP can be degraded completely in only about 2 h at about 90 °C, compared with the degradation degree (35%) of cured DGEBA, indicating good degradation and recycling properties of the DEHP.
固化热固性环氧树脂的降解和回收是该行业面临的主要挑战。在此，通过环氧氯丙烷与由柠檬酸和马来酸酐酯化反应得到的羧基封端超支化聚酯（DCHP）之间的反应，合成了一种低粘度、可降解的环氧封端超支化聚酯（DEHP）。采用傅里叶变换红外光谱和核磁共振氢谱对DCHP和DEHP的化学结构进行了表征。DEHP对双酚A二缩水甘油醚（DGEBA）具有增强增韧作用。随着DEHP含量和分子量的增加，固化后的DEHP/DGEBA复合材料的力学性能，包括拉伸强度、弯曲强度和冲击强度，先增加后降低。拉伸强度、弯曲强度和冲击强度的提高分别为34.2 - 43.4%、35.6 - 48.1%和117.9 - 137.8%。此外，DEHP还促进了固化后的DEHP/DGEBA复合材料的降解。固化后的DEHP/DGEBA复合材料的降解程度随DEHP含量和分子量的增加而增加。与固化DGEBA的降解程度（35%）相比，含12 wt% DEHP的复合材料在约90℃下仅约2 h就能完全降解，表明DEHP具有良好的降解和回收性能。
