Fabrication of mechanically robust and UV-resistant aramid fiber-based composite paper by adding nano-TiO₂ and nanofibrillated cellulose

Aramid fiber-based composite paper is widely used as an engineering material that is often used in outdoor environments. This inevitably cause ultraviolet (UV) damage to aramid fibers. In this work, nanotitanium dioxide (nano-TiO₂) was introduced to endow the composite a good UV-resistance while nanofibrillated cellulose (NFC) was used to disperse and deposit TiO₂ nanoparticles onto aramid fibers by physical interaction. Firstly, TiO₂ nanoparticles were treated by (γ-aminopropyl) triethoxysilane to achieve abundant amino-groups (–NH₂), which can interact with hydroxyl groups (–OH) of NFC. The results showed that NFC can significantly suppress nano-TiO₂ aggregation and result in a well-defined core–shell structure of TiO₂ nanoparticles uniformly coated onto aramid fibers. Also, the bridge effect of NFC and the reinforcing effect of nano-TiO₂ benefit the mechanical properties the aramid/NFC/TiO₂ composite. The maximum tensile index (~ 16.42 N m/g) and maximum tearing index (~ 9.28 mN m²/g) of aramid/NFC/TiO₂ composites increase by ~ 43.4 and ~ 26.1% in comparison with the control sample (~ 11.45 N m/g and ~ 7.36 mN m²/g), respectively. Meanwhile, the aramid/NFC/nano-TiO₂ composite achieves a good UV-resistant property because of the dominant light-absorbing ability of well-dispersed TiO₂ nanoparticles. Therefore, our work presents a green and damage-free approach to achieve high-performance aramid fiber composite especially with great UV resistance.