Fabrication And Properties Of Nano-hydroxyapatite/Poly(?-caprolactone)composite Fibers

With the rapid development of the global medical industry,biomedical materials have ushered in a glorious period of rapid development.Large scale fibers have unique advantages in the preparation of implantable devices like artificial blood vessels and artificial ligaments.As a result,many researchers have devoted to the development of new biomedical fibre materials.Poly(?-caprolactone)(PCL)is one kind of biodegradable materials authorized by FDA that have good biocompatibility and can be prepared into fibers by melt-spinning or electro-spinning.However,the mechanical properties of pure PCL fiber are weak which limites its application under the large load environment.Hydroxyapatite [Ca10(PO4)6(OH)2](HAp)is the main inorganic component in human bones and teeth.It is widely used in dental and bone damage repair.Nano-hydroxyapatite(NHA)particles not only have good biocompatibility,but also have osteoconduction and osteoinduction,which can induce the adhesion,growth and migration of bone cells.Numerous studies have shown that nanoparticles can enhance the mechanical properties of polymer matrix and NHA/PCL nanocrystalline composites are also in this category.In this study,PCL and NHA were blended and dispersed with the method of solution blending/ultrasonic dispersion/freeze drying.Then the NHA/PCL composite fibers were prepared in melt spinning.In-depth researches were did on the he dispersion of nano particles,the thermal properties,mechanical properties and biological activity of NHA/PCL composite fibers.The results show that NHA particles can be dispersed into PCL matrix with the method of solution blending/ultrasonic dispersion/freeze drying and the aggregation is inessential when the mass ratio is below 0.05.The diameter of composite fiber ranges from 131 nm to 250 nm and the diameter increases with the increasing of NHA/PCL mass ratio.DSC curves show that NHA particles hinder the neat arrangement of PCL molecular chains,reducing the melt temperature and crystallinity of PCL.At the same time,dispersed NHA particles accelerate the crystallization of PCL as the heterogeneous nucleation.NHA particles enhance the mechanical properties of PCL fibers,which is derived from the "viscous hindrance" special effect between NHA particles and PCL molecular chains.When the NHA/PCL mass ratio is 0.05,the mechanical properties of the composite fibers reache the optimal level,meeting the requirements of the textile machine.NHA particles increase the hydrophilicity of NHA/PCL composite fibers surface,and induce the composite fibers to mineralize the in SBF.