Electromagnetic Interference Shielding Performances of Carbon-Fiber-Reinforced PA11/PLA Composites in the X-Band Frequency Range

To solve the problem of increasing electromagnetic pollution,itis crucial to develop electromagnetic interference (EMI) shieldingmaterials. Using lightweight, inexpensive polymeric composites insteadof currently used metal shielding materials is promising. Therefore,bio-based polyamide 11/poly(lactic acid) composites with various carbonfiber (CF) amounts were prepared using commercial extrusion and injection/compressionmolding methods. The prepared composites' morphological, thermal,electrical conductivity, dielectric, and EMI shielding characteristicswere investigated. The strong adhesion between the matrix and CF isconfirmed by scanning electron microscopy. The addition of CF ledto an increase in thermal stability. As CFs formed a conductive networkin the matrix, direct current (DC) and alternative current (AC) conductivitiesof the matrix increased. Dielectric spectroscopy measurements showedan increase in the dielectric permittivity/energy-storage capabilityof the composites. Thus, the EMI shielding effectiveness (EMI SE)has also increased with the inclusion of CF. The EMI SE of the matrixincreased to 15, 23, and 28 dB, respectively, with the addition of10-20-30 wt % CF at 10 GHz, and these values are comparableor higher than other CF-reinforced polymer composites. Further analysisrevealed that shielding was primarily accomplished by the reflectionmechanism similar to the literature data. As a result, an EMI shieldingmaterial has been developed that can be used in commercially practicalapplications in the X-band region.