Ran Yin, Zheng Ling-Ji, Zeng Jian-Bing
Chongqing Key Laboratory of Soft-Matter Material Chemistry and Function Manufacturing, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
Materials (Basel). 2021 Feb 15;14(4):919. doi: 10.3390/ma14040919.
Epoxy vitrimers with reprocessability, recyclability, and a self-healing performance have attracted increasingly attention, but are usually fabricated through static curing procedures with a low production efficiency. Herein, we report a new approach to fabricate an epoxy vitrimer by dynamic crosslinking in a torque rheometer, using diglycidyl ether of bisphenol A and sebacic acid as the epoxy resin and curing agent, respectively, in the presence of zinc acetylacetonate as the transesterification catalyst. The optimal condition for fabricating the epoxy vitrimer (EVD) was dynamic crosslinking at 180 °C for ~11 min. A control epoxy vitrimer (EVS) was prepared by static curing at 180 °C for ~11 min. The structure, properties, and stress relaxation of the EVD and EVS were comparatively investigated in detail. The EVS did not cure completely during static curing, as evidenced by the continuously increasing gel fraction when subjected to compression molding. The gel fraction of the EVD did not change with compression molding at the same condition. The physical, mechanical, and stress relaxation properties of the EVD prepared by dynamic crosslinking were comparable to those of the EVS fabricated by static curing, despite small differences in the specific property parameters. This study demonstrated that dynamic crosslinking provides a new technique to efficiently fabricate an epoxy vitrimer.
具有可再加工性、可回收性和自愈性能的环氧类热致液晶聚合物已引起越来越多的关注，但通常是通过静态固化工艺制备，生产效率较低。在此，我们报道了一种在转矩流变仪中通过动态交联制备环氧类热致液晶聚合物的新方法，分别使用双酚A二缩水甘油醚和癸二酸作为环氧树脂和固化剂，并以乙酰丙酮锌作为酯交换催化剂。制备环氧类热致液晶聚合物（EVD）的最佳条件是在180℃下动态交联约11分钟。通过在180℃下静态固化约11分钟制备了对照环氧类热致液晶聚合物（EVS）。对EVD和EVS的结构、性能及应力松弛进行了详细的对比研究。EVS在静态固化过程中未完全固化，这在压缩模塑时凝胶分数持续增加得到证明。在相同条件下，EVD的凝胶分数在压缩模塑时没有变化。尽管在具体性能参数上存在微小差异，但通过动态交联制备的EVD的物理、机械和应力松弛性能与通过静态固化制备的EVS相当。本研究表明，动态交联为高效制备环氧类热致液晶聚合物提供了一种新技术。
