Effective thermal management and electromagnetic shielding have emerged as critical goals in contemporary electronic device development. However, effectively improving the thermal conductivity and electromagnetic shielding performance of polymer composites in multiple directions continues to pose significant challenges. In this work, inspired by the efficiency of interchange bridges in enabling vehicles to pass quickly in multiple directions, we employed a straightforward method to fabricate bidirectionally oriented carbon fiber (CF)/silicone rubber composites with an interchange-bridge-like structure. The high aspect ratio of CFs and their bidirectional orientation structure play a pivotal role in facilitating the formation of thermal and electrical pathways within the composites. Meanwhile, the bidirectionally oriented CF/silicone rubber composites showed a significant enhancement in tensile strength in both the vertical and horizontal directions, attributed to the cross-arrangement of CF arrays within the composites. At a filler content of 62.3 wt%, the bidirectionally oriented CF/silicone rubber composites had a high tensile strength of 6.18 MPa. The composites also exhibited an excellent thermal conductivity of 25.3 W/(m·K) and a remarkable electromagnetic interference shielding effectiveness of 61.6 dB. The bidirectionally oriented CF/silicone rubber composites show potential for addressing thermal management and electromagnetic shielding issues in electronic devices.Keywords:orientation;carbon fiber;thermal conductivity;electromagnetic interference shielding
The localized overheating of high-power and miniaturized electronic devices puts a pressing demand for developing organic phase change composites with rapid and uniform heat conduction. Herein, we constructed a bidirectionally oriented and interconnected boron nitride nanosheet (BNNS) network to obtain highly and uniformly thermal conductive phase change composites. The edge-center temperature gradient generated during freezing via a radial ice-template strategy actuated the BNNSs to radially align. The simultaneously appearing bottom-up temperature gradient induced BNNSs to closely stack along the vertical direction. The formed biaxially oriented and interlaced BNNS network in poly(ethylene glycol) (PEG) composites formed rapid and macroscopically uniform heat transfer pathways. The resultant phase change composite loaded with 5.1 vol % BNNSs exhibited the in-plane and through-plane thermal conductivities of 1.62 and 1.45 W/mK respectively, nearly 150% higher than that of the randomly distributed counterpart. The strong thermal conductive stability after intense thermal shock, favorable shape stability, and large latent heat were also gathered. Our work offers a valuable reference for developing desired thermal conductive phase change composites for efficient thermal management.
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