Preparation And Surface Modifications Of Braided Fiber Reinfocerd Resin Based Composites

Three-dimensional braided composites are excellent materials for surgery, aviation and other applications because of their good properties such as high specific strength. But the preparation of three-dimensional braided carbon fiber reinforced PEEK (C_3D/PEEK) composites is difficult and with few reports. C_3D/PEEK, three-dimensional braided carbon fiber reinforced epoxy (C_3D/EP), two-dimensional braided carbon fiber reinforced epoxy (C_2D/EP) composites, and so forth, are unsuitable to be deposited due to their low surface free energy, poor wettability and poor adhesion. As a result, surface modification of these composites will be greatly helpful to their applications.In this paper, the fiber commingled braiding and hot-pressing process for the preparation of C_3D/PEEK composites was studied. The effects of the plasma treatment on the chemical and physical changes of C_3D/PEEK, C_3D/EP and C_2D/EP surfaces were investigated. C_2D/EP composites were plasma treated, deposited with thin electric layers or ion implanted, and then copper plated with sulfuric acid based solution or composite plated in order to obtain copper or composite coatings with good adhesion and properties. The in vitro cytotoxicity experiment and deposition of Ca-P layer on C_3D/PEEK surfaces were carried out to evaluate the feasibility of more biomedicine applications of the composites.It was shown that C_3D/PEEK composites with excellent appearances and good interfacial adhesions could be prepared by vacuum hot-pressing at 370℃and 0.5 MPa after 2 h pre-dryness. The mechanical properties of composites could be evidently improved by optimization of fibre volume fraction and surface oxidation.Appropriate plasma treatment would increase the hydrophilities of composites because of the increased roughnesses and active groups. Metal ion implanted layers on composite surfaces could be obtained after ion implantation.The copper electroplating rate would be improved after plasma treatment, metal ion implantation, conductive polymer doping in epoxy resin matrix of the composites, or deposition of conductive layer on C_2D/EP surfaces. Crystalline grains of the coatings were markedly refined by nano-SiO2 in the acidic sulfate copper plating bath and the ceramic particles caused an increase in hardness of coatings.Osteoblast cells on C_3D/PEEK surfaces increased in amount with prolonged cell seeding time and presented a good shape. Ca-P layers were deposited on C_3D/PEEK composites, which had been immerged into 1.5 SBF after different pre-treatments. The globular grains of Ca-P layers after 28 d deposition were smaller and more uniform than that after 7 d deposition. Both the amount of Ca-P deposit and Ca/P atom ratio after alkali treatment were higher than that after the other pre-treatments.In conclusion, after appropriate surface modifications, C_3D/PEEK, C_3D/EP and C_2D/EP composites were well activated, roughened, metallized or bioactivated and thus would be employed for more applications.