Research On PA12 And Carbon Nanotube Composites For Fused Deposition Modeling

Fused Deposition Modeling(FDM)has become an important branch of 3D printing due to its advantages of safety and environmental protection,wide material sources,high integration,unlimited product shape and low cost,and has received extensive attention.Forming material is the bottleneck restricting the development and application of 3D printing technology.Nylon 12(PA12)is an important 3D printing material,but it is mainly used in selective laser sintering(SLS),and the research on using PA12 for FDM is not mature,so this study uses the PA12 powder recovered from SLS as the substrate and multi-walled carbon nanotubes(MWCNT)as the reinforcing agent and functionalizing agent to develop a high-performance PA12 composite printing material suitable for FDM and explore its application in printing Applications in absorbing structures.In order to improve the dispersibility of MWCNT,silane coupling agent KH560 and surfactant sodium dodecylbenzene sulfonate(SDBS)were selected as modifiers,and MWCNT and carboxylated MWCNT were compounded with nylon 12 powder by different blending methods.The results show that the solvent dispersion method can better improve its dispersibility,and the overall performance is better than that of the melting method;the modification effect of SDBS is slightly better than that of KH560;adding MWCNT to PA12 can significantly improve the tensile strength,flexural modulus,impact It has mechanical properties such as strength,and at the same time,its electrical conductivity and heat resistance are greatly improved.When the mass fraction of MWCNT is 7%,the comprehensive performance is the best,and its tensile strength,flexural modulus,impact strength,and Vicat softening temperature are higher than those of pure PA12.21.09%,32.25%,139.78% and 22.2°C,respectively,and the electrical conductivity increased by 11 orders of magnitude,and even increased by 13 orders of magnitude when the addition amount reached 10 wt.%;the melt fluidity of the composite material increased with the increase of MWCNT content However,as long as the MWCNT content is below 12%,the composite material can be drawn and printed smoothly.Under the printing conditions of the nozzle temperature of 240 °C and the printing speed of 30 mm/s,the tensile strength,flexural modulus,impact of the printed sample the strengths reach 94.45%,92.94%,and 85.51% of the injection-molded specimens,respectively,and the electrical conductivity is slightly better than that of the injection-molded specimens.For the carboxylated MWCNT-reinforced composite,2wt.% of carboxylated MWCNT combined with PA12 is the best choice,its tensile strength,flexural modulus and impact strength are 42.98%,36.62% and 159.11% higher than those of pure nylon,respectively.The best printing conditions obtained in the test are also the nozzle temperature of 240°C and the printing speed of 30mm/s.Finally,according to the electromagnetic properties of MWCNT/PA12 composites,the wave absorption simulation and experimental verification are carried out.In the flat plate model,the wave absorption performance of MWCNT/PA12 composites increases gradually with the increase of MWCNT content.When the MWCNT ratio reaches10 wt.% at 15.88 GHz,the material achieves a minimum reflection loss of-23.06 d B and a maximum effective absorption bandwidth of 5.31 GHz.At this ratio,the 3D-printed corner-cone absorbing structure has better absorbing performance than the analog value,and its effective The absorbing frequency band covers the entire frequency range of2~18GHz,and the minimum reflection loss-47.22 d B is obtained at 8.24 GHz,it shows great potential for application.