Preparation And Research Of Polylactic Acid Fiber Reinforced Hydroxyapatite/Chitosan Composite

Hydroxyapatite and chitosan composite materials is one of thehottest spot in the study of biological materials. Both of the materialsare excellent biocompatibility and biodegradability. Hydroxyapatite isalso a kind of important bone induced factor, but it is difficult to moldand brittleness when it used alone. Chitosan is a natural polymer whichcan be formed through a variety of means but with poor intensity. Thebiological performance and physical and mechanical properties could beto a certain extent improvement when the hydroxyapatite and chitosanare compounded, Such as the biological scaffold, bone tissue repair andalternative materials, etc. But its physical properties is still somedifference for the needs of bone tissue engineering used for bone repairand replace. Therefor, the enhancement of physical properties forhydroxyapatite/chitosan composite became more practical significance.Based on this, the article first put forward uesing biodegradable fiber tostrengthen the HA/CS composite, and we synthesized the compositematerials with the capable of biodegradable and a better mechanicalproperty at last. The composition, structure and properties of thematerial are characterized and analysed through FT-IR, XRD, SEM anduniversal testing machine.Firstly, the HA/CS composite was prepared via in-situ precipitationsynthesization on the basement of precipitation preparation for hydro-xyllapatite. We researched and summarized the molding influencefactors in the preparation processing of composite, for instance, theprecursor liquid deaeration, mould, solidification liquid, Gel processing,reaction time, etc. After optimization, we got the sample with rule shapeand no obvious physical defect. Through the examination it can beconfirmed that: hydroxyapatite crystal existing in the result product, And there were parts of B type carbon hydroxyl-apatite was generated;When the solidification liquid concentration was higher, it conductiveto the growth of hydroxyapatite (002) crystal-plane. Hydroxyapatitescattered evenly in the samples via in-situ precipitation, and thecomplex mechanical strength got certain ascend.Secondly, the polylactic acid fiber was adopted to enhance theHA/CS composite. Then we analysed the effect to the forming processafter doped fiber, And through the adjustment process that thepolylactic acid fiber could evenly disperse in the chitosan matrix.Through testing the sample it was found that the fiber was helpful to thetransformation and generation of hydroxyapatite in some degree. Thefiber can show a uniform dispersion when the content was2%, andcould produce a good interface cooperate which is necessary to theenhancement of complex mechanical strength.Through the orthogonal experiment, the main influence factors(hydroxyapatite content, fiber content, fiber length) which effected thecomposite curved performance were analyzed and summarized. Theflexural strength with hydroxyapatite content increased express littlechange, while the bending modulus producing small range of ascension;With the improvement of fiber content, the flexural strength andbending modulus reached peak at2wt%, and then dropt. The fiber waslonger, the flexural strength was higher, however,between10mm to50mm the strength valued small increase, the bending modulus ofcomposites achieved maximum when L=10mm. The elements peckingorder for the comprehensive mechanics performance of fiber reinforcedcomposite which was gotten by analysis of range was: Polylactic acidfiber content> polylactic acid fiber length> hydroxyapatite content.The compound was modificated by taking advantage of glutaral-dehyde cross-linking effect to chitosan. It was found that: thehydroxyapatite content significantly reduced in the complex ofcrosslinking, and crystal growth was bad, glutaraldehyde limited thehydroxyapatite formation. After mechanic comparison, the complexflexural strength improved obviously, the change rule was equal to the uncrosslinked complex which was performed first increase and thendropt. Because of the special physical and chemical properties ofchitosan and glutaraldehyde, the application of crosslinkingmodification subjected to a certain limit, the process should furtherimproved.To sum up, it is feasible to use polylactic acid fiber reinforcehydroxyapatite/chitosan composite material via in-situ precipitationsynthesization.