Mechanical properties of amine-cured epoxy composites reinforced with pristine protonated titanate nanotubes

Inorganic nanotubes are promising fillers for polymer composites. Among them, pristine protonated titanate nanotubes (p-TTNT), with high specific surface area and abundant hydroxyl surface groups, are good candidates for reinforcing amine-cured epoxy systems. Thus, epoxy composites filled with p-TTNT (≤ 3.0 wt. %, i.e. ≤ 1.1 vol. %) were prepared and their effect on the mechanical properties of the polymer matrix was studied. Young's modulus (E) and hardness (H) of the composites increased up to 19 and 17%, respectively, as demonstrated by microindentation tests, for 3.0 wt. % of p-TTNT, without functionalization. These increments could be attributed to the mutual compatibility, derived from the polar natures of p-TTNT and amine-cured epoxy, through the formation of hydrogen bonds. The wear resistance (H/E) of composites was maintained, independently of the p-TTNT content. Additionally, micromechanical models were successfully employed to predict the influence of the p-TTNT filler on the Young's modulus and hardness of the as-prepared composites.