Preparation and application research of composites with low vacuum outgassing and excellent electromagnetic sealing performance

Abstract Electromagnetic interference (EMI) shielding rubber effectively fills gaps in electronic devices to prevent electromagnetic (EM) leakage. However, research on the potential application of EMI shielding rubber in the field of space is limited. This study explores the optimal amount of silver-coated aluminum powder (SCA) in SCA/ methyl vinyl silicone rubber (MVQ) composites to balance the electrical and mechanical properties of EMI shielding rubber. The EMI shielding effectiveness (SE) of 41.8 vol% SCA/MVQ composite exceeded 90 dB in the frequency range between 100 and 1,200 MHz with a compression set of only 14%. To address the outgassing characteristics of silicone rubber in a vacuum environment, both pre-heating and post-heating treatments for reducing rubber volatility are explored, proving that silicone rubber followed by 4 h of post-heating treatment at 200°C, is an appropriate solution to reduce silicone rubber volatility, leading to the SCA/MVQ composite with a total mass loss of only 0.2%, and a collected volatile condensable material of only 0.02%. In addition, high reliability is crucial for EMI shielding materials. SCA/MVQ composite exhibits excellent adaptability to vacuum temperature cycles, with the EMI SE maintained at 90 dB after cycles. At room temperature, after 30 days of storage, the EMI SE of the composite remains at 90 dB. These findings indicate that SCA/MVQ composites exhibit broad potential applications in the field of EM sealing for aerospace electronic devices.