Flash heating creates durable, eco-friendly EMI-blocking materials
Researchers created a composite using flash-Joule-heated bamboo biochar, achieving 36.7 dB EMI shielding with 84% absorption and a 173% increase in fracture toughness.
Researchers have developed a novel composite material that enhances electromagnetic interference (EMI) shielding while maintaining mechanical strength. This material integrates flash-Joule-heated bamboo-derived biochar with a layer-by-layer polymer structure. The composite achieved an EMI shielding effectiveness of 36.7 dB, with 84% of the shielding resulting from absorption rather than reflection. Its fracture toughness improved by 173% compared to conventional PLA/PBAT blends.
The research team, led by Qingfa Zhang, aimed to create a material that efficiently absorbs electromagnetic energy without compromising mechanical performance. By employing flash Joule heating, surface modification, and a layered architecture, they established conductive pathways and reinforced polymer interfaces.
The process began with biochar produced from bamboo, subjected to flash Joule heating to enhance its conductive properties. The modified biochar was then treated with APTES to improve compatibility with the polymer matrix. Instead of dispersing the biochar throughout, it was strategically placed between layers of polylactic acid (PLA) and polybutylene adipate-co-terephthalate (PBAT), forming continuous conductive regions and stress-redistributing interfaces.
This composite demonstrated significant mechanical improvements, with tensile strength increasing from 14.1 MPa to 25.5 MPa and elongation at break more than doubling. The layered structure deflected cracks along complex paths, enhancing energy dissipation before failure.
Electrical performance also saw substantial gains, with conductivity reaching 12.8 S cm⁻¹ and an average EMI shielding effectiveness of 36.7 dB across the X-band frequency range. A conventionally prepared composite with the same biochar content achieved only 7.5 dB, underscoring the layered architecture's importance.
The material exhibited stable Joule heating behavior, reaching 58 °C at 9 V and maintaining performance over repeated cycles. Its multifunctionality suggests potential applications in electromagnetic protection, smart electronics, and thermal management.
This study highlights the potential of sustainable carbon materials to create multifunctional composites that combine electromagnetic protection with mechanical durability.
Source: Biochar Feed