Surface-Modified Nano-CeO₂ Synergistic With CTBN For Toughening Epoxy Resin Composites

Epoxy resin（EP）is a highly crosslinked thermosetting polymer widely used in automotive,adhesives,coatings,insulation materials,electronics,and aerospace industries because of its heat,mechanical,chemical,and corrosion resistance.However,the brittleness of crosslinked epoxy resin limits its application in some scenes.To improve its toughness and thermal properties at high temperatures,epoxy resin was toughened and modified.Due to the accessible agglomeration property of nano CeO₂,this paper used stearic acid to modify nano CeO₂ by ultrasonication,which changed it from hydrophilic-lipophobic to lipophilic-hydrophobic and improved its dispersibility in epoxy resin.In order to compare the effect of nano CeO₂ before and after modification on the performance enhancement of epoxy resin,nano CeO₂ toughened modified epoxy resin composites were prepared by ultrasonication method,regardless of whether the nano CeO₂ was modified by stearic acid or not,the mechanical properties of nano CeO₂/epoxy resin composites reached the best when the nano CeO₂ addition was 2 phr,and the modified nano CeO₂/epoxy resin mechanical properties were better than the unmodified ones,and the tensile strength,bending strength and impact strength of modified nano-CeO₂/epoxy resin composites were increased by 17MPa,41 MPa and 8 KJ/m²,respectively,compared with the unmodified nano-CeO₂/epoxy resin composites;SEM showed that the toughening mechanism of nano-CeO₂ toughened epoxy resin was crack deflection;and the increase of nano-CeO₂ would improve the thermal stability of nano-CeO₂/epoxy composites,but the thermal stability of modified nano-CeO₂to nano-CeO₂/epoxy composites is a little bit worse than that of unmodified nano-CeO₂.This paper used carboxy-terminated nitrile rubber（CTBN）as the main material.First,CTBN toughened epoxy resin was prepared by pre-crosslinking,and then mechanical blending and a partially interpenetrating polymer network structure were obtained.Its performance is tested and analyzed using infrared spectroscopy,scanning electron microscope,universal electronic tensile testing machine,and comprehensive thermal analyzer.The results show that CTBN can improve the mechanical strength and thermal stability of epoxy resin,and finally determine that the optimal addition amount of CTBN is15phr,the tensile strength of the cured product is 60.59MPa,the bending strength is 132MPa,the impact strength is 22 KJ/m² and The thermal decomposition temperature is 408°C.Based on the above research,adding 15 phr CTBN and different contents of nano-CeO₂modified epoxy resin simultaneously,with the increase of nano-CeO₂ content,the impact strength showed a trend of first increasing and then decreasing.When the nano-CeO₂ is 2phr,it reaches the maximum,reaching 29.3 KJ/m²;the TGA test shows that adding nano-CeO₂ leads to a further increase in the thermal stability of the CTBN/EP composite material,running 418°C;SEM shows that CTBN and nano-CeO₂ present Synergistic toughening effect.