Study Of The PLA/CDA/HA Composite Materials Prepared By Electrospinning

Poly-lactic acid (PLA) is a new degradable and environment-friendly material. The final product is lactic acid, which could excrete by body's metabolism. But its poor mechanical properties and thermal stability will limit its scope of application. Hydroxyapatite (HA) has good induction and bone conduction, but the material has a large elastic modulus, low mechanical strength and pure HA can't meet the need of bone fixation. Cellulose diacetate (CDA) is one kind of natural cellulose ester derivative with good biodegradability and biocompatibility. It don't induce adverse biological reactions, and the composite can enhance the stiffness and strength of the material. In this paper, the PLA/CDA/HA ternary composites was developed.It combined all the advantages of three raw materials, and it will be a high strength absorbable internal fixation material with good compatibility.In this paper, The grafting copolymer(PLA-g-CDA) was prepared by using Sn(Oct)2 as catalyst and grafting meso-lactide onto the cellulose diacetate in the vacuum melting environment.The results showed that in the vacuum reaction environment, feed weight ratio of meso-lactide and cellulose acetate was 4:1, catalyst content was 5%, reaction temperature was 140?, reaction time was 30min, the grafting rate of the product is higher.With the increase of PLA grafting rate, PLA-g-CDA was filming easier, compatibility was improved and mechanical properties has also been enhanced.HA was grafted by polyactide through two steps. First, lactic acid was grafted on the HA surface. Second, The grafting copolymer(PLA-g-HA) was prepared by using Sn(Oct)2 as catalyst and grafting meso-lactide onto the HL-g-HA in the vacuum melting environment. The results show that HA surface was coated with polylactic acid. The grafting rate of product reached 37.6% and had better time-dependent colloidal stability in chloroform compared with pure HA.The PLA/CDA/HA composite fibers were prepared by electrostatic spinning. The in vitro degradation properties were researched. The results showed that the fibers were hydrophilic after HA-modified and the PLA/CDA/HA fibers has the highest water absorption and weight loss. The pH of soaking solution remains basically unchanged. HA will induce the formation of bone-like hydroxyapatite on the surface of the fibers. After in vitro degradation for 8 weeks, the growth of bone-like apatite are the best on the surface of PLA/CDA/HA fibers and reflecting the excellent biological activity. After in vitro degradation for 28 days, different degrees of swell and fracture behavior have occured. The PLA/CDA/HA fibers have the largest fracture degree and reflects good biodegradability.