Wetting characteristics of epoxy resins modified by graphitic nanofibers with different functional groups

Resin wettability and flowability are critically important for manufacturing structural composites. Various nano-modified epoxy resins have shown great potential for improving composite performance. However, the effects of the nanofillers with different functional groups on wetting behaviors of epoxy resins have not been reported. In this work, wetting characteristics of epoxy resins modified by as-received graphitic nanofibers (GNFs), oxidized GNFs and reactive GNFs (re-GNFs) that we previously developed were studied. To quantitatively evaluate effects of the matrix modification on the wetting behavior, the measuring techniques of dynamic contact angle, Du Nouy ring, and droplet spreading rate tests were taken to characterize dynamic wetting behaviors of the nano-modified epoxy matrices. The study results showed that GNFs with different functional groups led to different effects on surface tension, advancing contact angle, spreading rate of epoxy resin. In particular, the re-GNF modified epoxy showed remarkably improved wettability that was observed from the special wetting phenomenon on a fabric surface. This nano-modified epoxy system will be significant for enabling energy efficient infusion processing for manufacturing high quality and high performance structural composite application.