To solve the problem of increasing electromagnetic pollution,
it
is crucial to develop electromagnetic interference (EMI) shielding
materials. Using lightweight, inexpensive polymeric composites instead
of currently used metal shielding materials is promising. Therefore,
bio-based polyamide 11/poly(lactic acid) composites with various carbon
fiber (CF) amounts were prepared using commercial extrusion and injection/compression
molding methods. The prepared composites’ morphological, thermal,
electrical conductivity, dielectric, and EMI shielding characteristics
were investigated. The strong adhesion between the matrix and CF is
confirmed by scanning electron microscopy. The addition of CF led
to an increase in thermal stability. As CFs formed a conductive network
in the matrix, direct current (DC) and alternative current (AC) conductivities
of the matrix increased. Dielectric spectroscopy measurements showed
an increase in the dielectric permittivity/energy-storage capability
of the composites. Thus, the EMI shielding effectiveness (EMI SE)
has also increased with the inclusion of CF. The EMI SE of the matrix
increased to 15, 23, and 28 dB, respectively, with the addition of
10–20–30 wt % CF at 10 GHz, and these values are comparable
or higher than other CF-reinforced polymer composites. Further analysis
revealed that shielding was primarily accomplished by the reflection
mechanism similar to the literature data. As a result, an EMI shielding
material has been developed that can be used in commercially practical
applications in the X-band region.