The Preparation And Properties Research Of Magnesium Oxide Wiskers/Poly L-lactic Acid Composite Bone Repair Materials

Poly(L-lactic acid)(PLLA) has been widely used as bone tissue repair materials due to its biodegradability, biocompatibility and good mechanical and processing properties. However, there are some shortcomings as bone tissue repair materials using PLLA alone, such as the mechanical strength is not ideal, especially lack of toughness,the formation of lactic acid during the degradation of PLLA easy cause aseptic infection reaction, implanted in the body it can’t X-ray imaging, etc. Magnesium oxide(Mg O)whisker is a kind of fibrous monocrystal with a certain length to diameter ratio,excellent mechanical strength and modulus, and it is a kind of ideal polymer enhanced toughening filler. In addition, Mg O whisker is a kind of alkaline oxide, X-ray imaging, and magnesium ions with excel ent characteristics of promoting bone healing.This paper adopts Mg O whisker to reinforce the strength and toughness of PLLA, and through the Mg O whisker to neutralize acid degradation prod ucts of PLLA, and make up for the shotcomings while using PLLA alone. At the same time, through the surface graft modification of Mg O whisker, effectively solve the dispersion of Mg O whisker in the matrix of PLLA and improve the interface binding force, finally get a Mg O whisker/PLLA composite as bone tissue repair materials with good comprehensive performance.To this end, Mg CO3·3H2O whiskers, the precursors of Mg O whiskers is prepared by solution method, and then calcined to Mg O whiskers, and it has been characterized the morphology and composition by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and X-ray diffraction(XRD). It turned out that, when Na2CO3 solution and Mg C l2 solution with amount of substance ratio of 1:1, with the concentration of C(Na2CO3)= C(Mg C l2)=0.5mol/L, and during the same time keep the stirring speed at 800r/min, we get the ideal Mg O whisker with good morphology, high length-diameter ratio, no holes or defect.Based on the ring opening polymerization of lactide in the surface of Mg O whisker to grafted PLLA chain segments to solve the problem that the compatibility of the two phases is not good and the fillers poorly dispersed in the PLLA matrix. To study the change of the structure and morphology before and after grafting through IR, XRD, TG, TEM and SEM. The results show that, under laboratory conditions, the PLLA segment successfully grafted on the suffers of Mg O wiskers. While the crystal structure and morphology of wiskers have no change.In this paper, thro ugh mixing mill blending, and the injection molding machine to get Mg O wiskers/PLLA, g-Mg O wiskers/PLLA composites standard sample, and conducted a comprehensive research on the performance of the materials. We find that g-Mg O whiskers in the matrix of PLLA are scattered significantly better than Mg O whiskers; With the content of whiskers increasing, the surface contact Angle of g-Mg O whiskers/PLLA composites down first and then increased, and it is lower than that of the same content of Mg O whisker. Add a certain content of Mg O whisker into PLLA matrix can significantly improve the mechanical properties of PLLA matrix, and to join the same content of g-Mg O whisker toughening effect of PLLA matrix enhancement is better. When the content of g-Mg O whisker is 1%, the tensile strength of the composite material is 69.72 MPa, which increased 23.2%, compared with the pure PLLA. The maximum elongation at break of Mg O whisker/PLLA composite is 8.86%, with the whisker content of 0.5%, while the maximum elongation at break of g-Mg O whiskers/PLLA composite appear in the content of 1%, is about 9.9%, compared with the pure PLLA increased by 43.9%.