Preparation And Properties Of Magnesium Alloy/polylactic Acid Medical Composites

Many problems in clinical application were appeared in the traditional biodegradable polymer material polylactic because of its poor mechanical properties and acidic degradation products.The biomedical application of magnesium and magneium alloys were limited for its rapid degradation.In this paper,magnesium and magnesium alloy/polylactic acid interpenetrating structure composite materials were designed and prepared,the advantages of magnesium and magnesium alloys and polylactic acid were complementary.The degradation performance of composite materials was studied by immersion test and electrochemical test.We evaluated the mechanical properties of the composite material by the tensile and bending tests.The change law of the mechanical properties in SBF(simulated body fluid)and the effects of parameters(helix angle,wire diameter)on the mechanical properties of composite materials were analyzed.The biocompatibility of composite materials was discussed by the antibacterial test,blood compatibility test and cytotoxicity test.The study finds that the composite materials with magnesium content 40%and 50%have a uniform network structure,low and uniform corrosion rate,and low hydrogen evolution rate.The p H change of SBF is affected by the magnesium content.The alkaline environment accelerates the decomposition of polylactic acid,and the degradation products include calcium phosphate,Mg(OH)₂.Large helix angle is beneficial to the longitudinal strengthening of the magnesium wire.The mechanical properties of the composite material with a 120°helix angle(tensile strength:101.9 MPa,compression strength:81.4 MPa)is better than 90°and 60°.The strengthening effect of?0.25 mm,?0.38 mm,?0.54 mm Mg-Sn-Mn alloy wire is better than?0.4 mm pure Mg,tensile strength is 111.3 MPa,119.3 MPa and 123.9 MPa,compression strength is 91.5MPa,95.8 MPa and 94.6 MPa.The interfacial bonding strength of composite materials is important for the mechanical properties.The interface strength,tensile strength and compression strength are improved by surface treatment of HF and Na OH.In the 10 days of SBF immersion,the mechanical properties of composite materials depend on the corrosion of magnesium wire.In the last 4 days,the mechanical properties of composite materials depend on the interfacial bonding strength.Antibacterial experiments show that the magnesium in the composite material can increase the p H value of the bacterial solution,and the alkaline environment formed i nhibits the growth of E.coli and Staphylococcus aureus.The composite materials with magnesium content 50%and 60%have higher antibacterial rate(77.4%?87.1%a nd 86.3%?94.0%).The composite material with magnesium content 40%has a low antibacterial rate.All of the hemolysis rates of composite materials are lower than 5%(0.99?1.5%),which can meet the medical requirements for hemolysis rates of biom edical materials.The results of CCK show that the composite materials are not cytoto xic to L-929 cells.