Study On Properties Of Epoxy Resin Modified By Carboxyl Terminated Liquid Nitrile Rubber And Cyclodextrin

At present,many studies have found that the addition of third phase such as nanoparticles can effectively improve the properties of epoxy resin toughened by carboxyl terminated liquid nitrile rubber.Therefore,in this paper,carboxymethylatedβ-cyclodextrin was added to the epoxy resin composites modified by carboxyl terminated liquid nitrile rubber.The properties of the modified epoxy resin were studied,and the potential of cyclodextrin as a rigid filler to improve rubber toughening epoxy resin was explored.In order to improve the interfacial interaction and compatibility betweenβ-cyclodextrin and resin matrix,carboxymethy l-β-cyclodextrin(CM-β-CD)was prepared by nucleophilic substitution method withβ-cyclodextrin and chloroacetic acid as raw materials.The effect of reaction conditions on the synthesis of CM-β-CD was analyzed by IR,NMR and the degree of substitution.In addition,the effect of CTBN content on the properties of epoxy resin was studied by mechanical properties.It was found that the elongation at break increased by 183.24%,while the bending strength and modulus decreased only by 12.4% and 25.6% when the content of CTBN was 20 phr.After that,the ternary nanocomposites were prepared by blending of CM-β-CD with 20 phr CTBN and epoxy resin.The properties of the nanocomposites were studied by DSC,TGA,universal material tester and SEM.TG and DSC showed that when 0.5wt% CM-β-CD was added,glass transition temperature(T_g)did not change significantly but thermal stability was slightly higher than those toughened by CTBN without CM-β-CD.In addition,it was found that the introduction of carboxymethyl-β-cyclodextrin into the carboxyl terminated nitrile rubber/epoxy resin composite system could improve the tensile modulus and elongation at break of the composite;however,the addition of carboxymethy l-β-cyclodextrin also led to the decrease of flexural strength,flexural modulus and impact strength of the composites.The SEM results showed that the rubber particles on the fracture surface had obvious"Sea-Island"two-phase structure with obvious debonding holes and stress whitenings,but cyclodextrins were separated from the resin and had a certain crack pinning effect.