Sandwich-Structured Pla/Pbat/Carbon Fiber Composites for Enhanced Electromagnetic Interference Shielding, Flame Retardancy and Controlled Degradation

Abstract

Green flame-retardant electromagnetic shielding materials have received significant attention in recent years. In this study, amine-functionalized MXene (MXene-NH2) nanosheets were synthesized via surface amination, and silica-coated ammonium polyphosphate (SA) containing epoxy groups was prepared via the sol-gel method. The polylactic acid/polybutylene terephthalate/MXene-NH2/SA (PLA/PBAT/M/A) layer was fabricated through melt blending, serving as the outer layer of the sandwich-structured PLA/PBAT/M/A composite. Polydopamine-coated carbon fiber cloth (PDA@CC) was used as the intermediate layer to construct sandwich-structured composites. This design synergistically improves the interfacial bonding force and PDA@CC becomes an effective bridge for stress transfer, effectively enhancing the mechanical properties. Notably, the tensile and notched impact strengths of PLA7/PBAT3/2M/8A composite were 111.2 MPa and 22.1 kJ/m2, respectively. Additionally, MXene-NH2 and SA exhibited strong synergistic catalytic carbonization, cross-linked network and physical barrier effects in flame retardancy to form dense char layer. The limiting oxygen index (LOI) value of PLA7/PBAT3/2M/8A composite was 30.4, and the peak heat release rate (PHRR) and total heat release (THR) decreased by 67.7% and 46.2%, respectively. The combination of the conductive carbon fiber fabric and MXene in the sandwich structure further enhanced EMI shielding efficiency, achieving a shielding effectiveness of 54.9 dB. The hydroxyl groups on the surface of MXene and a large number of interfaces can degradate the PLA/PBAT/M/A layer and retain CC layer. This study provides a new method for fabricating the sandwich-structured PLA/PBAT/M/A composites with excellent mechanical properties, flame retardancy, EMI shielding properties and controlled degradation.

Keywords: PLA, Carbon fiber, MXene, EMI shielding, Flame retardancy, Degradation