Fabrication of Flame Retardant NR/BR Composites With Excellent Vulcanization Characteristics and Mechanical Properties Based on a Novel Phosphorus–Nitrogen Microencapsulated Flame Retardant

ABSTRACT Natural rubber (NR) has high strength and excellent processability, and cis ‐polybutadiene rubber (BR) has excellent abrasion and low‐temperature resistance, but both NR and BR are highly flammable in air, and it is a challenge to improve the flame retardant properties of NR and BR while maintaining high mechanical properties. In this study, polyaniline (PANI) coated with aluminum diethyl hypophosphite (ADP) was used to form a microencapsulated flame retardant PANI@ADP. The flame retardant was characterized by FTIR, XPS, SEM, particle size analysis, and TGA. PANI@ADP was added to natural NR/BR composites. The results showed: compared with ADP, the limiting oxygen index of NR/BR composites with 15 parts PANI@ADP was increased from 23.5% to 24.7%, and the LOI of NR/BR composites with 20 parts PANI@ADP was 27.4%. The flame retardant mechanism of PANI@ADP was analyzed through the characterization of residual carbon in NR/BR composites. In addition, the addition of PANI@ADP to NR/BR improves the vulcanization properties of the composites and enhances the mechanical properties of the composites compared to ADP. This study enabled the NR/BR composites to maintain high mechanical properties while improving the flame retardant properties.