Using industrial technologies, we prepared a sodium montmorillonite (Na-MMT) slurry and an irradiated styrenebutadiene rubber (SBR) latex, and then spray dried them to produce a novel, ultrafine fully vulcanized powder SBR (UFPSBR)/Na-MMT nanocompound powder in which the nanoscale UFPSBR particles and exfoliated Na-MMT were isolated and stuck together. When the UFPSBR/Na-MMT nanocompound powder was mixed with crude SBR, the exfoliated Na-MMT was disorderly dispersed in the SBR matrix because of the carrier nature of the UFPSBR particle, which is compatible with SBR and disperses easily in the SBR matrix, and the SBR/UFPSBR/Na-MMT ternary nanocomposite was prepared. When compared with SBR/Na-MMT binary composites, the SBR/UFPSBR/Na-MMT ternary nanocomposite has a shorter vulcanization time, higher strength, and better flame retardancy because of the good dispersion of exfoliated Na-MMT in the SBR matrix with a Na-MMT loading range of 4 phr. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2013