Enhanced interlaminar fracture toughness of unidirectional carbon fiber/epoxy composites modified with sprayed multi-walled carbon nanotubes

Abstract

A recently reported solvent spraying technique was used herein for incorporation of multi-walled carbon nanotubes (MWCNTs) on unidirectional carbon fiber/epoxy prepregs. The role of the agglomerates reduction of oxidized MWCNTs on Mode-I interlaminar fracture toughness (G_IC) of laminated composites was investigated using double cantilever beam tests. Multiscale laminate composites were fabricated using MWCNTs without and with an acid oxidation, agglomerates reduction (AR) and a sequential treatment based on oxidation and AR. For comparison, specimens without MWCNTs were also prepared and tested. Fourier transform infrared analysis shows evidence of an important amount of oxygenated functional groups on the surface of as-received and oxidized MWCNTs. The results also show Mode-I fracture toughness improvements for all the laminated composites compared to reference samples. A substantial 52% increase in the average G_IC initiation was achieved for laminated composites reinforced with oxidized AR-MWCNTs prepared with only 0.05 wt.% MWCNTs.

Keywords:

• Carbon nanotubes
• carbon fiber
• prepreg
• fracture toughness
• Mode-I

Acknowledgements

The authors would like to thank the assistance of Antonio Banderas at CIDESI for the SEM analysis. Technical support of José Miguel Martínez, Edgar Miranda and Ricardo Lozada (all of them from CIDESI) is also appreciated.