Preparation And Modification Of Inorganic Phosphate/PEEK Composites

Pure PEEK is difficult to meet the property requirements with the rapidly development of engineering technology,especially the heat resistance and thermo-mechanical strength,which need to be strengthened urgently.PEEK composites are one of the important development directions of engineering materials in the future,due to the high heat resistance of PEEK itself,the improvement in heat resistance is limited when using organic polymers as reinforcing materials.When using inorganic nano-materials as reinforcing materials,due to the pores generated between the nano particles and PEEK matrix,the reinforcing effect decreases with the aging of the composite material.Therefore,improving the heat resistance and thermostatically properties is still an important problem in preparing high-performance PEEK composites.In this paper,the phosphate was modified by using Si3N4,Al N,Al2O3 and Cu2 O,and the modified phosphate and PEEK were mixed by ultrasonic dispersion method to obtain the preform of composites.Modified phosphate/PEEK composite was prepared by compression molding-curing at 350?to improve the adhesive force generated by curing and cross-linking.The structure of the modified phosphate/composite was analyzed by XRD and FT-IR,and the results show that the addition of modified phosphate had no obvious affect structure of PEEK.DSC and TG were used to analyze the curing behavior and heat resistance of the composite and the results show that the modified phosphate without affecting the curing process of PEEK,but the heat resistance of PEEK was enhanced.Especially,when Al2O3 modified is used as the reinforcing material,the 20% weight loss temperature(T20)of the composite is 50?higher than pure PEEK.The microstructure of the composite was observed by SEM.The results showed that Al2O3 modified phosphate and PEEK form excellent interface and compatibility.Through analysis,different inorganic particle modified phosphates have different effects on the mechanical strength of the composite.Al2O3 modified phosphates exhibited the most excellent reinforcement effect,with the compressive strength increased from 156.31 MPa to 321.39 MPa,which is 105.6%higher,while still maintaining high bending strength.In addition,the addition of phosphate enhanced the thermal aging resistance of PEEK.In order to study the interface structure between phosphate and PEEK,selected Al2O3 modified phosphates as reinforcement material,and analyze the structure and properties of composite with different phosphate contents.XRD and FT-IR were taken to study the structure of the composite,which show that the content of Al2O3 modified phosphate have not affect the curing reaction in PEEK matrix.DSC was used to study the curing behaviorof the composite and shows that the curing temperature is positively correlated with the Al2O3 modified phosphate content.Furthermore,the composite was heat treated at 800?to remove the PEEK matrix,and the microscopic morphology of the residue was observed by SEM,which show that the interpenetrating cross-linked network structure(IPNs)is formed in Al2O3 modified phosphate and PEEK,and the structure of IPN is related to the phosphate content.The combined performance analysis results show that the formation of IPNs improves the thermo-mechanical strength and heat resistance of the composite.The composite with 40wt% Al2O3 modified phosphate has the most complete IPNs structure,and the tensile and compressive strength at room temperature have increased by 15.9% and74.5% than pure PEEK respectively,reaching 110.47 MPa and 314.33 MPa.To further improve the performance of phosphate/PEEK composite materials,PEEK was sulfonated by direct sulfonation method.The effects of varied H2SO4 concentrate and sulfonation time on the sulfonation degree of PEEK were characterized by FT-IR and EDS,which shows that the S-PEEK treated with 80%H2SO4 as sulfonating agent for 60 min has high sulfonation degree and no large-area entanglement,and is most suitable to be used as the matrix of high-performance phosphate/S-PEEK composite.The test results of mechanical strength show that the flexural strength and compressive strength of S-PEEK-based composites are increased by 13.76 MPa and 4.2MPa compared with the composite material without sulfonation,respectively.