Study on High-Efficiency Charring Flame Retardancy and Good Thermal Conductivity in Polycarbonate Composites Including Maleimide Aluminum Alkyl Phosphinate/Boron Nitride

Abstract

High thermal conductivity and high flame-retardant charring properties can meet the technical requirements for fire safety of polycarbonate (PC) used in 5G high-frequency devices. In this study, a novel aluminum maleimide phosphinate (NBAP) with ideal fire-retardant charring properties was synthesized, and a synergistic system of flame retardant and thermal conductivity comprising boron nitride (BN) and NBAP was developed. 3%NBAP/20%BN/PC can obtain outstanding flame retardancy with 37.6% of LOI values and a UL 94 V-0 rating of the vertical burning test; this sample also can obtain 231 kW/m² of PHRR, 33.9 MJ/m² of THR, and 11.2 m² of TSP. The results were much lower than neat PC. This result was attributed to the excellent synergistic charring effect of NBAP and BN, which obtained outstanding flame barrier in the condensed phase. In terms of thermal conductivity, NBAP containing metallic aluminum ions promotes the enhancement of PC thermal conductivity and combined with lamellar BN to build an excellent thermal conductivity pathway, thus effectively increasing the thermal conductivity by 4.57 times compared to neat PC. In a word, this study can provide a significant exploration for constructing high-performance PC composites with fire retardance and heat conduction.