Surface Modification By Eco-friendly Electroless Copper Plating And Electromagnetic Shielding Performance Of Carbon Fiber Non-woven Fabric

Driven by relentless market demand,consumer electronics are rapidly updated,bringing great convenience to humans but causing a worrying problem of electromagnetic(EM)pollution.On the one hand,the high-speed operation capability of electronic equipment is continuously enhanced.And it will be extremely susceptible to external electromagnetic interference when exposing chronically to EM environment.on the other hand,electronic equipment should be reformed in the direction of flexibility,miniaturization and light-weight with the development of human society.Therefore,a flexible,hydrophobic,eco-friendly,highly-efficient-shielding and reliable copper-plated carbon fiber non-woven fabric(CuCFN/PDMS)is proposed.The effects of preparation parameters on the electrical conductivity,wetting and electromagnetic shielding properties of Cu-CFN/PDMS are explored and their mechanisms are discussed in detail.Considering the advantages and disadvantages of carbon fiber non-woven fabric used in the electromagnetic shielding applications,a carbon fiber/core-sheath fiber composite nonwoven fabric(CFN)with porous structure is proposed.The mathematical relationship between structural parameters and electrical conductivity of CFN is established.According to the theory of electromagnetic shielding and hydrophobic enhancement,we design a Cu-CFN/PDMS film,which is composed of CFN with porous structure,Cu layer with continuously-conductive structure and PDMS layer with low surface energy.A copper-modified carbon fiber non-woven fabric(Cu-CFN)is fabricated by an ecofriendly polydopamine(PDA)-modified electroless plating process.Then,in order to manufacture a flexible,hydrophobic and highly-efficient-shielding Cu-CFN/PDMS film,the low surface energy and forming protective layer treatments are applied to Cu-CFN by a dipping method.The surface of CFN is covered with rough,dense,continuous and uniform copper particles.And the PDMS layer prevents the copper particles from corrosion of air.What's more,this formed film still has good flexibility and foldability.In the electrical conductivity test,it is found that the electrical conductivity of original CFN can be improved greatly by using electroless copper plating process.To a certain extent,the electrical conductivity of the Cu-CFN/PDMS film is increased with the increasing activation concentration and deposition time of the copper layer.But the activation concentration has a limited effect on improving the electrical conductivity of the film.In the wettability test,it is found that the improved hydrophobicity of Cu-CFN/PDMS film can be attributed to the porous structure of CFN,the rough structure of copper layer and the low surface energy of PDMS layer.And the Cu-CFN/PDMS film can still exhibit a good hydrophobic property,even in the acid or alkali environment.In the electromagnetic shielding test,it is found that the increase in the activation concentration and copper deposition time can also improve the electromagnetic shielding performance of the Cu-CFN/PDMS film.Compared with most of the researching materials,this film achieves extremely high electromagnetic shielding performance at low density and thickness.Furthermore,the film can still maintain its fine electromagnetic shielding performance after the treatment of continuous heating and ultrasonic operation.