Fracture resistance, thermal and electrical properties of epoxy composites containing aligned carbon nanotubes by low magnetic field

The alignment of carbon nanotubes (CNTs) with residual catalyst Ni particles in epoxy resin (EP) was achieved under a low magnetic field of 0.4 T. EP composites containing different loading of CNTs were prepared at 60 °C based on the rheology results of CNT/EP suspensions. The effects of CNT loading and magnetic field on the fracture toughness (KIC), glass transition temperature (Tg) and electrical properties of the composites were studied. The obtained results showed significant enhancements in KIC, independent of the orientation of the CNTs, compared to neat epoxy. The maximum increase (∼51%) was achieved by composites with 3 wt.% aligned CNTs transverse to crack growth. Additionally, composites with magnetically aligned CNTs displayed anisotropy in KIC. Compared to CNT/EP composites with no applied magnetic field, the KIC increase was less effective at high CNT loading. Finally, toughening mechanisms, Tg and electrical conductivity results were discussed.