摘要
选用耐候性好、易加工、易成膜且保色性好的水性丙烯酸涂料作为基体,添加高效导电填料碳纳米管(CNT),通过添加不同比例的碳纳米管,以实现阻抗渐变型电磁屏蔽材料的有效构筑;当CNT质量含量达到1 wt％+5 wt％+25 wt％以及1 wt％+10 wt％+25 wt％时制备的多层级复合涂层,在K波段(18～27 GHz)与Ka波段(27～40GHz),即5G高频波段表现出优异的低反射高效电磁屏蔽性能,电磁屏蔽效能(EMISE)均可达到20 dB以上,且呈现出低反射的特点,吸收系数最多可以达到0.92.
Abstract
The arrival of the 5G communication era has brought great convenience to people's lives,and at the same time generated a large amount of electromagnetic pollution.Therefore,there is an urgent need to develop high-performance electromagnetic shielding materials to solve the current serious problem of electromagnetic pollution.In this study,we prepared water-soluble polyacrylic acid/carbon nanotube(PAA/CNT)composites with three-layer impedance gradient structures by multiple coatings.The modification of carbon nanotubes were fully mixed with dispersant under ultrasonic condition to obtain a homogeneous dispersion,which were then centrifuged and dried.The modified carbon nanotubes and water-soluble acrylic acid were mixed in a specific ratio to obtain a homogeneous dispersion.The obtained PAA/CNT composite dispersion was coated on a polyethylene terephthalate(PET)substrate using a brush applicator.The composite coating was obtained by repeated coating after drying the coating.The difference of CNT content between each layer can realize the difference of conductivity,and then build the impedance gradient to realize the introduction-absorption-reflection-re-absorption of electromagnetic wave,so that the electromagnetic shielding performance can be optimized.When the CNT content is 5 wt％,the electromagnetic shielding value is 9.57 dB.With the increase of CNT content to 25 wt％,the electromagnetic shielding value can be up to 28.05 dB.In particular,when the CNT content of each coating is 1％,5％,25％,and 1％,10％,25％,respectively,the electromagnetic interference shielding efficiency(EMI SE)can be up to more than 20 dB,with a maximum A-power coeffiicients value of 0.92.Furthermore,waterborne acrylic resins enables the composite materials to maintain excellent weathering resistance.After 200 h of salt spray test,the electromagnetic shielding effect of the material can still achieve 27.85 dB.Such excellent corrosion resistance makes it promising for use in harsh environments.This work provides a strategy for the development of the preparation of electromagnetic dissipative materials without the need for organic solvents,which is environmentally friendly,simple,efficient and cost-effective.
基金项目
国家自然科学基金(52003106)
国家自然科学基金(52161135302)
中央高校基本科研业务费专项(JUSRP12032)
中央高校基本科研业务费专项(2232019A3-03)
NETL
NSTL
维普
万方数据