Surface Grafting of Amino Terminated Dendrimers on Carbon Fibers and Their Influence on Interfacial Properties With Epoxy Resin

ABSTRACT Here, different generations of amino terminated dendrimers were chemically grafted on carbon fiber (CF) surface, using trimesic acid and ethylenediamine as small molecule initiators, and the influence of amino density on interfacial properties with epoxy resin was further investigated. The x‐ray photoelectron spectroscopy results show that stepwise grafting of amino terminated dendrimers on CF surface was successful, thus obtaining higher amino density. Raman spectroscopy also confirmed the more nitrogen‐containing functional groups introduced by amino terminated dendrimers and simultaneously verified the introduction of high‐density amorphous carbon structure. Besides, grafting of amino terminated dendrimers on CF surface also increased the fiber roughness and surface coverage of grafted molecules. After grafting of 2nd generation amino terminated dendrimers, the polarity component and dispersion component of CF‐g 2 ‐NH 2 increased to 15.4 mJ/m 2 and 26.1 mJ/m 2 , respectively, and the surface free energy reached 41.5 mJ/m 2 . Meanwhile, their IFSS was significantly improved, reaching 46.62 MPa, an increase of 43.3% compared to untreated CF, while their single fiber strength had hardly decreased. This significant improvement in the IFSS between grafted CF and epoxy resin was mainly attributed to higher active amino groups, surface roughness, and wetting performance, which benefitted from the surface grafting of amino terminated dendrimers on CF surface.