Mode II interlaminar fracture toughness of unidirectional fiber-reinforced polymer matrix composites with synthetic boehmite nanosheets at room temperature and low temperature

The nanosheet boehmite (AlOOH) was synthesized and used as reinforcing agent to toughen carbon fiber-reinforced polymers. The purity, morphology, size and composition of the AlOOH nanosheets were investigated by the methods of XRD, SEM, TEM and FTIR, respectively. Interlaminar fracture toughness for mode II deformation was investigated for carbon fiber-reinforced polymers toughened by AlOOH nanosheets varying the contents at room temperature (RT, 293k) and at low temperature (LT, 77k). The fracture surfaces were examined by SEM to correlate with the interlaminar fracture properties. The results indicated that the synthesized AlOOH nanosheets were pure crystalline and of high purity. By TEM, the thickness of the lamellar AlOOH sample is about 22 nm. The end-notched flexure test results show that interlaminar fracture toughness of unidirectional carbon fiber-reinforced polymer with the same content AlOOH nanosheets (0, 1, 1.5, 2, 2.5, 3 wt.%) at LT is higher than that at RT. The interlaminar fracture toughness reaches the highest when the AlOOH nanosheets content equals 2% at RT. But at LT, the highest interlaminar fracture toughness appeared in the carbon fiber-reinforced polymers without AlOOH nanosheets.