| In recent years,due to the aging of the population and the increase in bone loss and bone defects caused by accidents,the demand for implants in the biomedical field has become increasingly urgent.Metal implant materials are prone to stress shielding due to their elastic modulus not matching the human body during service.And in the long-term use process,there are also harmful ion release,wear and corrosion and other problems.PEEK materials have been gradually used in surgical trauma and artificial joint replacement due to their excellent properties such as good corrosion resistance,X-ray transmittance and elastic modulus close to human cortical bone.The topography of the natural bone surface is inextricably linked to its biocompatibility.In this paper,the following studies were mainly carried out on the surface morphology of natural pig bone bone as the basis for the modification of PEEK implants.The mechanical properties and safety properties of PEEK material implantation were studied by three-point bending test and cytotoxicity test.The surface morphology of natural pig bones was used as the basis for the modification of PEEK implants.By observing its surface topography,it is found that the surface is distributed with grooves and microporous structures.The processing of grooves and microporous structures adopts the double modification method of cutting processing and sulfonation treatment.In order to obtain a porous structure closer to the surface of pig bone,two methods of constructing pore structure,standing sulfonation treatment and ultrasound-assisted sulfonation treatment,were explored,and it was found that the formation of a large pore structure on the surface of the material by ultrasound-assisted sulfonation treatment was closer to the surface of pig bone.PEEK is a temperature-sensitive material,and the effect of temperature on PEEK materials is mainly studied.Differential scanning calorimetry analysis was used to obtain the glass transition temperature of PEEK material of 164 °C and melting point of 340 °C.The cutting temperature in the cutting process is measured by thermocouple method,and the maximum temperature of the measuring point is 151 °C within the selected cutting data range,which is close to the glass transition temperature of PEEK material.Through the low temperature compression test,it can be seen that the yield strength of PEEK material is 137 MPa at 20 °C and 201.6 MPa at-196 °C,which is increased by 47%.Low temperature can improve the stiffness of PEEK materials.Through the cutting test,the influence of cutting data on the surface quality,chip morphology and cutting force of PEEK machining was studied,and the roughness prediction model was established.With the increase of cutting speed,the roughness of the machined surface shows a tendency to decrease under both cooling conditions.Compared with normal temperature dry cutting,low-defect surface can be obtained under processing under lowtemperature liquid nitrogen cutting.And under different feeds,a groove structure similar to the surface of natural pig bones is processed.On the groove surface obtained by machining,the microporous structure was constructed using concentrated sulfuric acid as a sulfonating reagent.The safety and functionality of the modified surface were evaluated,and the surface after sulfonation treatment was not cytotoxic.Osteoblasts attach along the cutting groove,and clusters of cells growing along the pores are observed around the porous structure.Compared with the unsulfonated surface,the porous surface after sulfonation treatment is more conducive to the adhesion and proliferation of cells.The modification method combining cutting and sulfonation treatment has important application value for improving the biocompatibility of PEEK materials. |
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