Toughening mechanisms of epoxy resin using aminated metal-organic framework as additive

•UiO-66 and UiO-66-NH2 were successfully introduced into epoxy resin (EP).•MOFs have good structural integrity and high dispersity in MOF/EP composites.•Increased value of Tg was achieved for the prepared UiO-66-NH2/EP composite.•The as-formed UiO-66-NH2/EP composite displays the best mechanical properties.•Toughening mechanisms of EP by using aminated MOF as additive are proposed.