Carbon Fiber Reinforced Polylactic Acid / Hydroxyapatite Ternary Composites Preparation And Degradation

Poly-lactic acid(PLA) since there being the good compatibility and degradable, hence widely having been used to the absorbing operation thread and internal fixation of bone fracture. Hydroxyapayite (HA) has been widely used as internal fracture fixation materials, due to its similarity to bone mineral in structure and composition, and it's a good biocompatibility to human tissue. However, the pure HA can't meet the need of bone fixation because of its fragility, low mechanical strength, easy rupture, and weak fatigue resistance in the humoral surrounding. Carbon materials don't induce ill results, their strengths and stiffness are similar to the bone, so they have already been one kind of the most important inorganic biomedical materials. In this paper, carbon fiber (CF) reinforced hydroxylapatite (HA)/ploylactide (PLA) degradable biomaterial was developed. It combined all the advantages of the three raw materials, and it will be a high strength absorbable internal fixation material with good compatibility.In this paper, CF/HA/PLA degradable biomaterial was developed by solvent blending. The in vitro degradation properties were researched. The composites have excellent mechanical properties. After in vitro degradation for 3 months, the flexural strength and flexural modulus fell 30% and 36% respectively, and the shear strength held on the 190 MPa level, had good maintenance of mechanical properties. From the SEM images, the degradation began from the interfaces, there were gaps at the interfaces. Water uptake increased to 5%, but the mass loss was only 1.6%.Interfaces in the composite are important factors that influence the mechanical properties of the composites. Lactide was prepared from lactic acid with the stannous octoate as the catalyst. And HA was grafted by polyactide through two steps. First, lactic acid was grafted on the HA by dehydration between the carboxyl on the lactic acid and hydroxyl on the surface of HA. The grafting polymerization of lactide was carried out with stannous octoate as the initiator under anhydrous and vacuum conditions. The amount of grafted polymer determined by thermal gravimetricanalysis (TGA) was about 17% in weight, and had better time-dependent colloidal stability in the chloroform compared with pure HA.Hydroxyapatie coating was prepared from the 5 times concentrations simulate body fluids (SBF). Compared with the pure HA, the IR spectra were basically similar; and in the X-ray Diffraction (XRD) patterns of the HA coatings, a peak appeared at the 2(?)33° and it belonged to HA crystals; but the Ca/P rate was 1.33, a little lower than the pure HA's 1.67.