Preparation Of PEEK-based Composite Filaments And Research Of Wave Absorption Properties

Absorbing materials can effectively suppress electromagnetic waves and are widely used in radiant control,electromagnetic compatibility,stealth,and other fields.As the power density of electronic devices gradually increases,certain application scenarios require the working temperature of absorbing materials to reach 150℃,or even more than300℃.However,most of the plastic,rubber,foam,and other traditional absorbing materials are usually used at temperatures below 150℃ and cannot be applied to the temperature range of 150-250℃.Since there is less research on absorbing materials applied to this temperature range,it is significant to develop absorbing materials with good temperature resistance and absorbing characteristics.In this thesis,polyether ether ketone/carbon nanotubes(PEEK/CNTs)were used to prepare PEEK-based composite filaments using a melt extrusion process.By analyzing the effects of material formulation and process parameters on the flowability,dispersibility,and homogeneity of the filaments,the optimal preparation process for filaments with different contents of CNTs was obtained,and the maximum filling amount of CNTs in the filaments was determined by combining the requirements of the equipment on the performance of the filaments.The mechanical and electromagnetic properties of the filaments were investigated,and the calculation method of the electromagnetic parameters of the filaments was optimized based on the effective medium theory,and the flat-plate level absorbing structures with various configurations were prepared by printing with FDM technology.The specific work and conclusions are as follows:(1)The melt index of the filament was improved by adding high-temperature lubricant to a fixed percentage of PEEK/CNTs material,and the optimal filling amount of lubricant was determined to be 2 wt%.Optimized the process parameters of filament preparation,and obtained the rule that increasing the extrusion temperature and screw speed will increase the filament diameter and increasing the traction speed will decrease the filament diameter combined with the requirements of the printing equipment for the filament used,the filament diameter was precisely controlled within the range of1.75±0.05 mm.Based on the optimization of the process parameters,the optimal preparation process for the filament with different CNTs content was investigated,and the rule that increasing the CNTs content decreases the melt index of the filament was obtained,and the maximum filling amount of CNTs in the filament was determined to be8 wt%,taking into account the requirements of the equipment for the flowability and mechanical properties of the filament.(2)Based on the effective medium theory and computer-aided,the calculation method of electromagnetic parameters of PEEK/CNTs filaments was optimized,and the experimental comparison proved that this calculation method can be used for applications with low accuracy.This calculation method obtained the regulation law of electromagnetic parameters of filaments at 0.5-18 GHz: The dielectric constant of PEEK/CNTs filaments increases with CNTs.(3)A formulation of filament prepared under the optimal process was selected and combined with FDM technology to print a variety of configurations of flat-plate level absorbing structures.The absorbing properties and mechanical properties of the structures were characterized and optimized.In this thesis,the PEEK-based composite wire material is studied in terms of material selection,preparation process,and testing.The results show that the absorbing material is expected to be popularized in civil and military applications.