Effects Of Ultraviolet Irradiation And Moisture On Hydrogenated Epoxy/Cycloliphatic Amine/Nano TiO₂ Composite

Epoxy resin（EP）is one of the most crucial matrix materials in fields such as aerospace,energy and automobile.However,various environmental factors may adversely affect EP due to the lack of weather resistance.New hydrogenated epoxy/alicyclic amine/nano titanium dioxide（Ti O₂）were designed and prepared in this paper in order to enhance weather-resistance of EP.A variety of pure EP systems with different chemical structures and compositions were prepared,and one system with better weather-resistance was selected through characterization.Ti O₂ and the DA were added for surface organic modification.Three kinds of nanocomposites systems were prepared based on DA-Ti O₂.The aging characteristics of epoxy nanocomposites and the specific response of nanoparticles to aging environment were further studied.The main content of this research is as follows:（1）Accelerated ultraviolet aging test was carried out on the pure EP system prepared above,and the surface chemical state（FTIR-ATR）,carbonyl index（CI）,surface micromorphology（SEM）,macroscopic mechanical and thermodynamic properties were studied.H-DGEBA has a more stable chemical structure under ultraviolet radiation than DGEBA,but its mechanical properties are not as good as DGEBA.The performance resin system H4 serves as the resin matrix in the composite material.（2）In the moisture aging test,the water absorption rates of the four pure EP systems were different,and the tensile strength and thermodynamic properties also changed after aging.“Secondary cross-linking”was observed between water molecules and epoxy network in the process of hygroscopicity via the calculation of crosslink density and free volume fraction,and the difference in hygroscopicity is caused by the difference of free volume fraction of structure.（3）The differences in chemical structure and microstructure of Ti O₂ and DA-Ti O₂ after modification were systematically investigated.The modification of DA would reduce the specific surface energy of Ti O₂,thereby improving the dispersibility of Ti O₂ in epoxy matrix.And the grafting rate of DA was estimated by thermogravimetric analysis（TGA）.（4）Based on the successful preparation of DA-Ti O2,three nano-epoxy resin composites were designed and prepared.EP/Ti O₂ was characterized to be more weather-resistant,although EP/DA-Ti O₂ has good mechanical properties.The modification of DA weakened the specific surface energy of Ti O₂ and rendered it less sensitive to UV rays.And through AFM and moisture absorption test,it is found that the composite has different aging characteristics compared with pure EP,such as hydrophobicity,and the abnormally rough surface formed by the releasing of nanoparticles.