Preparation and Performance Regulation of Carbon-Fiber-Reinforced PC/ABS Composites for Microwave Absorption and EMI Shielding

Abstract

The rapid development of high-frequency electronic devices and fifth-generation wireless communication systems has increased the demand for polymer-based materials with both electromagnetic interference shielding and microwave absorption capabilities. In this work, carbon-fiber-reinforced polycarbonate/acrylonitrile–butadiene–styrene composites were prepared by twin-screw melt compounding, and the effects of carbon fiber content, fiber type, and feeding strategy on the mechanical and electromagnetic properties were investigated. Two feeding modes, namely main feeding and side feeding, were compared to regulate the fiber length distribution and conductive-network structure in the PC/ABS matrix. Compared with main feeding, side feeding effectively reduced fiber breakage during extrusion. For example, the number-average fiber length of MC10%-SF reached 165.7 μm, whereas that of MC10% prepared by main feeding was only 111.7 μm. The retained long fibers promoted the formation of continuous conductive pathways, leading to enhanced dielectric loss and improved electromagnetic attenuation. Among the investigated formulations, MC20%-SF exhibited a maximum reflection loss of -51 dB at 15.5 GHz with a thickness of 1.7 mm and an effective absorption bandwidth of 4.56 GHz. Meanwhile, it maintained favorable mechanical properties, including a tensile strength of 115 MPa and a flexural modulus of 13,249 MPa. For EMI shielding, HC30%-SF achieved a total shielding effectiveness close to 55 dB in the X-band. These results indicate that controlling fiber length through side feeding is an effective strategy for balancing mechanical reinforcement, microwave absorption, and EMI shielding performance in PC/ABS-based conductive composites.