Preparation And Properties Of Silver/Hydroxyapatite/Polyamide 6 Composite

Polyamide 6?PA6?is well-known as its excellent toughness and abrasion resistance,as well as good biocompatibility because of the plentiful amide bonds.However,when PA6 is used alone in repairing of the bone tissue,its strength and osteogenic activity are poor.hydroxyapatite?HA?is the main inorganic component of human bones and has good biological activity and osteoinductive capacity.However,when HA is used alone,its mechanical properties is poor,and it is fragile and difficult to be used in repairing of the bone tissue.Therefore,combining PA6 with HA,which make composite have good mechanical and biocompatibility properties,however,good biocompatibility of HA/PA6 brings some new problems,such as the high risk to adsorb bacteria,and the wasy bacterial infection,leading to the failure of bone implantation.Nano silver,has the advantages of broad-spectrum bacteriostatic and available antibacterial behavior,in this thesis,we prepared and characterized Ag/HA/PA6 composites as biomaterials for application.Firstly,two complexation agents of ferric chloride and calcium chloride were used to break the hydrogen bond of PA6.After PA6 was dissolved completely,The dispersible solution with different content of HA was added to PA6 solution,and then add C₂H₅OH-H₂O solution to make the HA/PA6composite precipitated and then prepared by hot-press moulding approach.The optimum process parameters of composite materials were analyzed.The effects of two complexants on the structure,crystallization behavior,dynamic thermo-mechanical properties and frictional properties of HA/PA6 composites were analyzed.The effects of nanosilver loading of Ag/HA/PA6 on the antibacterial behavior,cytotoxicity and in vitro biological activity of the composites were initially explored.The results are as following:?1?Through the investigation of the molar ratio and reaction temperature,the optimum process parameters for preparing the composite material are obtained.Two kinds of complexing agents were used to dissolve and disperse PA6 respectively,and different HA/PA6 composite powders were prepared through the solvent precipitation method.?2?The structure and crystal form of the composite powders prepared by different complexing agents were characterized.FT-IR,XRD and DSC analyses showed that the functional groups and crystal structure of HA in the composite powders was maintained with FeCl₃ as the complexing agent.The functional groups and crystal structure of the HA/PA6 composite powders remained intact with CaCl₂ as the complexing agent.A small shift of the peaks in the FT-IR profiles proves that the filler HA has a certain interaction with the matrix PA6.?3?The thermal stability of composite powders prepared by different complexing agents was characterized.TG results show that the thermal stability of composite powders prepared with FeCl₃ as the complexing agent is much lower than that of raw material PA6.The accurate amount of HA is lower than idea value.Whereas the composite material prepared with CaCl₂ as a complexing agent possesses thermal stability comparable to that of PA6,and the final weight loss rate matches well with the theoretical addition amount,indirectly reflecting that HA has a good dispersion in PA6.?4?The thermo-mechanical properties of composites prepared with different complexing agents were characterized.The DMA results showed that the composites prepared with both complexing agents had the highest modulus at 40%HA content,which can satisfy the requirements of human bones.?5?The friction properties of the composites prepared by two complexing agents were characterized.The results show that the composites prepared with CaCl₂ as the complexing agent have lower friction coefficient and shallower wear scar depth.Among them,when the HA content is 40%,the HA/PA6composites prepared with CaCl₂ as the complexing agent had the best friction and wear properties,where the friction coefficient was 0.6,and the depth of wear scar was the shallowest with the value of 38.82?m.?6?Silver was loaded into HA/PA6?CaCl₂?composite by plasma reduction method.The results showed that when the theoretical load of Ag+was 0.6 wt%,the Ag/HA/PA6 composites exhibited promising antibacterial properties and no cytotoxicity was generated.Besides,this material shows good biocompatibility and in vitro biological activity,and can be regarded as potential biomaterials for the further application.