具有超高介电常数的海绵/炭黑-硼酸盐/硅橡胶复合材料

Sponge/carbon black-borates/silicone rubber composite with ultra-high dielectric constant

通过浸渍法制备了密胺海绵(MS)/导电炭黑-硼酸盐(CB@B)复合物,并进一步真空灌注硅橡胶(SR)后制备了MS/CB@B/SR复合材料。使用XRD、SEM对复合材料的物相、微观结构进行表征并测试了其导电与介电性能、压敏特性和吸波性能。研究发现,CB@B复合物利用MS模板在复合材料内部构建了三维逾渗网络,其导电逾渗阈值为1.48%(体积分数),CB与B对提高复合材料性能具有显著的协同作用。随着CB浓度提高,复合材料的导电性和介电常数逐步提高,当CB浓度为14mg/mL时,复合材料的体积电阻率最低可达到6.7×10^4Ω·cm,介电常数在1kHz时高达1.67×10^4,当样品厚度为3mm时,在30.97GHz处出现最低反射率(RL=-33.17dB),吸波带宽(RL<-10dB)为5.38GHz。当CB浓度为10mg/mL时,复合材料的电阻和介电常数还表现出较高的压缩应变灵敏度。

Melamine sponge (MS)/conductive carbon black-borates (CB@B) compound (MS/CB@B) were prepared by impregnation method,and then infused by silicone rubber (SR) to obtain the MS/CB@B/SR composite.The chemical composition and microstructure of the composites were characterized by XRD and SEM,and the conductivity,dielectric properties,pressure sensitive behaviors and microwave absorbing properties were tested.It was found that the CB@B compound had constructed a three-dimensional percolation network inside the composite using MS template with the conductive percolation threshold of 1.48vol%.CB and B had a significant synergistic effect on improving the properties of the composite.With the increase of CB concentration,the conductivity and dielectric constant of the composites increased gradually.At the CB concentration of 14 mg/mL,the composite had the volume resistivity of 6.7×10^4 Ω·cm,and an ultra-high dielectric constant of 1.67×10^4 at 1 kHz.The composite with sample thickness of 3 mm showed the excellent microwave absorbing performance with the strongest absorption peak of-33.17 dB at 30.97 GHz and the absorption bandwidth of 5.38 GHz .At the CB concentration of 10 mg/mL,the resistance and dielectric constant of the composite also exhibited high compressive strain sensitivity.