Short carbon nanotubes: From matrix toughening to interlaminar toughening of CFRP composites

Carbon nanotubes (CNTs) are widely used for strengthening and toughening of resin matrix. However, the improvement of resin matrix toughness can't be effectively transferred to carbon fiber reinforced polymer (CFRP) composites due to the fiber filtration effect. Here, short carbon nanotubes (SCNTs, average length <2 & mu;m) were added to the epoxy resin and then used as the matrix of CFRP. The test results showed that 0.5 wt% SCNTs is the optimal mass fraction for matrix toughening, which enhanced the maximum strain, maximum stress and toughness of the epoxy resin by 43.3%, 10.1% and 65.9%, respectively, and the mode I interlaminar fracture toughness of resultant CFRPs was increased by as much as 86.7%. The superior interlaminar toughening efficiency of SCNTs can be ascribed to their smaller size, which enables them to penetrate into the tiny gaps of carbon fiber yarns, thus not only effectively avoiding the fiber filtration effect and making them evenly distributed in the matrix, but also strengthening the interfaces between epoxy resin and carbon fibers.

Automated summary

Short carbon nanotubes (SCNTs) with average length less than 2 μm were added to epoxy resin as the matrix of carbon fiber reinforced polymer (CFRP) composites. The addition of 0.5 wt% SCNTs significantly enhanced the toughness of the matrix, resulting in increased strain, stress, and interlaminar fracture toughness of the epoxy resin and CFRPs. The superior interlaminar toughening efficiency of SCNTs can be attributed to their small size, which allows them to penetrate into the tiny gaps of carbon fiber yarns and strengthen the interfaces between epoxy resin and carbon fibers.