Synthesis and Performance Analysis of Repolymerized Epoxy Resin Composites Toughened by Modified n‐CeO₂ and CTBN

Epoxy resin is a widely used thermosetting resin, but its application is limited due to its high brittleness and poor toughness after curing. In this study, we used repolymerized epoxy resin as the matrix and added carboxyl‐terminated nitrile rubber (CTBN) and nano‐cerium dioxide (n‐CeO 2 ) to improve its impact strength without compromising its thermal properties. The test results show that with 15 wt.% CTBN, the tensile strength of the cured product is 60.59 MPa, the flexural strength is 132 MPa, and the impact strength is 22 KJ/m 2 , which are 206%, 200%, and 424% higher than those of pure epoxy resin, respectively. To further enhance the toughening effect, we introduced n‐CeO 2 on the basis of 15 wt.% CTBN. The study found that with increasing n‐CeO 2 content, the impact strength first increased and then decreased. When the n‐CeO 2 content is 2 wt.%, the impact strength of the resin reaches 29.3 KJ/m 2 , which is 32% higher than that of CTBN. Additionally, thermogravimetric analysis (TGA) shows that the addition of n‐CeO 2 significantly improves the thermal stability of CTBN/EP composites. Scanning electron microscopy (SEM) analysis reveals that CTBN cavitation occurs in the resin; n‐CeO 2 plays a crucial role in particle debonding and crack pinning.