Effects of aligned carbon nanotubes in matrix on mechanical properties of carbon fiber reinforced epoxy composites at cryogenic temperature

In order to improve the micro-cracks resistance of carbon fiber reinforced epoxy (CF/EP) at cryogenic temperature (77 K), Fe₃O₄ modified O-MWCNTs (Fe₃O₄-O-MWCNTs) with good paramagnetic properties were prepared by co-precipitation method. The effects of the addtions of aligned Fe₃O₄-O-MWCNTs on the properties of epoxy (EP) and CF/EP composites at 77 K were studied. The results show that the aligned Fe₃O₄-O-MWCNTs can effectively improve the mechanical properties of EP matrix at 77 K and reduce the coefficient of thermal expansion (α) of EP matrix. It can also obviously improve the micro-crack resistance of CF/EP composites at 77 K. Comparing to the neat EP, α of aligned Fe₃O₄-O-MWCNTs modified EP composite decreases by 41.6%. Comparing to CF/EP composite, the micro-crack density of aligned Fe₃O₄-O-MWCNTs modified CF/EP composite at 77 K decreases by 56.2%.