Effect of aluminum diethylphosphinate/aluminum hypophosphite on the high abrasion and flame resistance of NR/BR composites

The flame‐retardants aluminum diethylphosphinate (ADP) and aluminum hypophosphite (ALHP) were introduced into natural rubber (NR) and butadiene rubber (BR) to prepare composites. The effects of the two flame‐retardants on the processing characteristics, physical properties, flame resistance, mechanical properties and abrasion resistance of the composites were studied and compared. Results showed that both flame‐retardants delayed the vulcanization of the composites and increased the Mooney viscosity and ADP exhibited a more evident increase. Both ADP and ALHP improved the flame resistances of the composites, but the ADP improvement was more obvious, and the limiting oxygen index (LOI) of the composites increased from 22% to 28.5%, when ADP was added at 45 phr. The addition of ADP and ALHP reduced the rebound and increased hardness of the composites. The two flame‐retardants reduced the tensile strength, tensile elongation, and tear strength of the composites; both flame‐retardants adversely affect abrasion resistance, with abrasion loss of composite increased by 100% and 85% at 45 phr of ADP and ALHP, respectively. ADP can considerably improve LOI of the composites compared with ALHP, but it has a more significant negative impact on abrasion resistance. Flame retardance mechanism and abrasive mechanism of aluminum diethylphosphinate/rubber compounds.