Improvement of Adhesion and Wettability at PEEK-Resin/TiO₂ Interface by Use of Crystal-Orientation Control

抄録

The adhesion strength and wettability at the interfaces between a polyetheretherketone (PEEK) resin and titanium dioxide (TiO₂), which have become more important for direct joining of PEEK resin and titanium (Ti), is investigated by using molecular simulations. Especially, the dependence of the adhesion strength and wettability on crystal orientations of rutile TiO₂ were investigated to realize strong joint between the PEEK resin and TiO₂. By putting a PEEK-resin sphere on a rutile TiO₂ surface and by heating the system to 650 K, the contact angles at the interfaces were calculated to evaluate the wettability. After the system is cooled to 300 K from 650 K, the adhesive fracture energy is calculated to evaluate the adhesion strength. The results of the contact angles showed that PEEK resin on the TiO₂(100) and that on the TiO₂(001) surface have low wettability with large contact angles. On the other hand, PEEK resin on the TiO₂(110) surface has high wettability with a small contact angle. The results of the adhesive fracture energies showed that the adhesion at the PEEK-resin/TiO₂(100) and PEEK-resin/TiO₂(001) interfaces are weak. On the other hand, the adhesion at the PEEK-resin/TiO₂(110) interface is strong. To clarify the reason that the higher wettability and higher adhesion strength are obtained at the PEEK/TiO₂(110) interface, atomic configurations were visualized. The atomic configuration showed that the lattice-matched coherent interface is realized and the surface atomic density is high only at the PEEK/TiO₂(110) interface. Therefore, the lattice matching and the high surface atomic density at the PEEK/TiO₂(001) interface are considered to be dominant factors in the high wettability and strong adhesion. The experimental results show that the wettability and critical load of scratch tests increase in the order: PEEK/TiO₂(100)< PEEK/TiO₂(001)<< PEEK/TiO₂(110).