ABSTRACT Natural rubber (NR) and cis‐polybutadiene rubber (BR) are widely used due to their respective advantages, such as high strength, excellent processability, wear resistance, and low‐temperature resistance. However, the high flammability and the toxic smoke released during combustion of these two rubbers limit their application. To address this issue, this study developed a microencapsulated flame retardant named PBEG@Cu, consisting of expanded graphite (EG) as the core and copper ions together with bis2‐(methacryloyloxy)ethyl phosphate (BMEP) as the shell. This flame retardant was incorporated into NR/BR composites. Experimental results showed that when the total addition of PBEG@Cu reached 20 phr, the fire hazard of the composite was significantly reduced. The limiting oxygen index increased from 19.6% to 25.3%. Compared with pure NR/BR, the total heat release (THR) and peak heat release rate (pHRR) of the composite decreased by 26.1% and 31.7%, respectively. Furthermore, the maximum smoke density (D s,max ) dropped by 24.6%, while the thermal conductivity increased by 65.3%. By achieving a synergistic balance among flame retardancy, smoke suppression, and thermal conductivity, it offers new insights for the design of high‐performance rubber composites for applications with stringent fire safety requirements.
Yu et al. (Fri,) studied this question.