Study On Preparation And Characterization Of N-HAP/PVA Blend Composition Fibers

Poly（vinyl alcohol）（PVA） fiber is one of the most important synthetic fibers with good moisture absorption and high strength etc..However,its deficiencies,such as poor wet strength and hot water resistance,have limited its application in certain areas.In recent years,with the development of the production of PVA fibers,researches on physical and chemical modifications of PVA have attracted increasing attention,and mainly focused on the PVA blends and composites research.As one kind of important bio-ceramics,nano-hydroxyapatite（n-HAP） has been used to compound many types of materials to strengthen their bioactivities.Brittleness of n-HAP could be improved through compounding the polymers,thus getting stable,reliable and tenacious biomaterials.In this paper,Silane coupling agent was used to modify n-HAP particles and the effect was observed with polarizing microscope.It had been showed that KH570 was the best Silane coupling agent to modify n-HAP particles,the aggregation of n-HAP particles were suppressed and uniformly dispersed in the PVA solution. The static rheological properties were tested using HAKKE rheometer in order to research the effect of n-HAP content and temperature on the shear viscosities of the n-HAP/PVA blend spinning dopes.The results showed that the blend solutions were shear-thinning non-Newtonian fluid. N-HAP played the role of cross-linking in the dope,which increased shear viscosity and the degree of structure,thus decreasing the spinnability.The viscous flow activation energy of blend solutions declined with the content of n-HAP increased.N-HAP/PVA blend composite fibers were spun with dry jet wet spinning,the cross section of which was circular and compact.Study shows that interaction of hydrogen bond between n-HAP and PVA was obviously existed,which broke the orderly array of PVA macromolecules and reduced its crystallization ratio.Because of the uniformly dispersed n-HAP particles interacted with PVA macromolecules,it was improved the thermal and mechanical properties of the blend composite fibers that a proper amount of n-HAP was added into the PVA libers.N-HAP was synthesized in PVA dilute solution by in-situ hydrothermal synthesis,and n-HAP crystals had crystal integrity and stability structure characteristics.Synthesized n-HAP with different ratios were coated by flocculation poly（vinyl alcohol）.With the increase of PVA content,the length of n-HAP reduced and the diameter increased.In the same shear rate,the viscosity of n-HAP/PVA blend solution decreased while the size of n-HAP increased.With the size of n-HAP increased,the breaking strength of the n-HAP/PVA blend composite fibers increased,but when the size of n-HAP comes to the ratio of （Ca（NO₃）₂+（NH₄）₃PO₄）/PVA to 22:11,the breaking strength up to the maximum,then decreased gradually,the rate of elongation at break showed opposite phenomenon to the breaking strength of the n-HAP/PVA blend composite fibers used synthesized n-HAP by in-situ hydrothermal synthesis increased 55%,modulus increased 300%.