“…In previous studies [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], the adhesion of PEEK can be improved by different physical and chemical surface modifications and treatments, including sandblasting [ 6 , 7 , 8 , 9 , 10 ], acid treatment [ 8 , 9 , 10 , 11 , 12 , 13 ], laser beam emission [ 14 , 15 , 16 ], ultraviolet (UV) light irradiation [ 17 ], and plasma treatment [ 18 , 19 , 20 , 21 , 22 , 23 ]. These studies showed that the bond strengths of PEEK and fiber-reinforced PEEKs increase following their surface modification.…”