Preparation And Performance Of Hydroxyapatite/Poly (Vinyl Alcohol) Composites

Hydroxyapatite(HAP) is widely used as bone reparation and orthopedic replacements,as well as for dendal replacement and reparation because of excellent biocompatibility,bioactivity and osteoconductivity. In recent years,A variety of methods for HAP preparation have been developed.However,it is dificult to effectively control the preparation of HAP in morphology and size by a single method.Therefore,in the paper, we systematically studied controllable preparation of nanometer hydroxyapatite via in situ hydroxythermal synthesis method using poly(vinyl alcohol)(PVA) as molecular template.Furthermore,the effect of hydroxythermal reaction time and template agent concentration on size and morphology of HAP particles in the composites was systematically studied.The results indicated that the development(size and morphology) of the HAP nanocrystals precipitated in an aqueous solution of PVA was influenced by the polymer concentration and hydrothermal time.The morphology of HAP/PVA particles grew from irregular spherical and short rod-like particle to regular long rod-like particle with increase of hydroxythermal reaction time from 0 h to 16 h.However,the morphology don't obviously change when the hydroxythermal reaction time increase from 16 h to 72 h.Simultaneously,it was also found that the crystallite size of HAP in HAP/PVA particles become smaller with the increase of template agent PVA concentration.Gel-spun process is used in this paper to investigate the relation between structure and properties of PVA/HAP fibers based on the principle that the interactions between the PVA and HAP induced orientation of the HAP in PVA/HAP composite fibers,with measurements on the mechanical properties,XRD,FTIR,DSC,TG methods.The results indicated that:(1)The breaking strength of PVA/HAP fiber enhanced with the increase content of the HAP.It maybe explained that a good adhesive interface formed because of predominant interaction of HAP with the PVA.What's more,with the increase content of HAP,the stress concentration phenomenon improved.(2)The reason that the breaking strength of PVA/HAP fibers and pure PVA fibers improved significantly with increase of the draw ratio is because oritation structure is formed during the draw process.(3)Compared with the pure PVA fiber,the breaking strength and modulus of the PVA/HAP composite fibers is higher in the same draw ratio,showing that the interactions between the PVA and HAP induced orientation of the HAP.(4)The heat-resistant properties of PVA/HAP improved with the increase content of HAP.