Abstract: Polyetherimide (PEI)/ Nickel (Ni) gradient electromagnetic shielding films were prepared by the use of suspension casting method with the principle of gravity settling. The corrosion resistance of PEI/Ni gradient electromagnetic shielding films under the environment of wet, hot and humid, strong alkali, acid rain, dilute strong acid and concentrated strong acid were studied. The scanning electron microscopy, vector network analyzer and universal tensile testing machine were used to characterize the micro-morphology, electromagnetic shielding effectiveness and the mechanical property. Changes of the gradient composite films before and after immersing in etching solution were compared. Results showed that the gradient distribution structure brought a difference in the degree of corrosion on the top and bottom surfaces of the film, and the resin-rich top surface was more resistant to corrosion than that of the metal-rich bottom surface. The corrosion resistance of PEI/Ni gradient electromagnetic shielding film was good in the humid, hot and humid, strong alkali and acid rain simulated solutions. After being immersed in those etching solution at the temperature of 60 ℃ for 30 d, the appearance of PEI/Ni gradient electromagnetic shielding films had little change. The electromagnetic shielding effectiveness did not decline, which was maintain about 40 dB, and tensile strength maintained at 60 MPa above. Experimental results showed that the PEI/Ni gradient film has better corrosion resistance and show higher application value. However, such kind of composite with metal powder as a filler was not resistant to strong acid corrosion. Small holes appeared on the surface of the sample after being immersed in strong acid etching solution at 60 ℃ for 10 d, because a chemical reaction between the metal Ni and the strong acid occured, and which resulting in electromagnetic wave leakage. As a result, it loss its electromagnetic shielding effect after being soaked within 5 d when the H2SO4 solution concentration was higher than 0.1 mol/L.
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