Novel method for preparation of carboxylated nitrile rubber-natural rubberblends using bis(diisopropyl)thiophosphoryl polysulfides

Bis(diisopropyl)thiophosphoryl trisulfide (DIPTRI) and bis(diisopropyl) thi ophosphoryl tetrasulfide (DIPTET) are successfully used as a novel coupling agent and accelerator, respectively, to covulcanize an elastomer blend com prising polar carboxylated nitrile rubber (XNBR) and nonpolar natural rubbe r (NR), These compounds are capable of forming a chemical link between thes e dissimilar rubbers to produce a technologically compatible blend as judge d by a swelling experiment. The blend vulcanizates thus produced exhibit en hanced physical properties that can further be improved by adopting the two -stage vulcanization technique and also by judicious selection of the NR:XN BR ratio. The blend morphology assessed by scanning electron microcroscopy micrographs accounts for significant improvement in the physical properties of the blend vulcanizates, particularly in two-stage vulcanization. (C) 20 01 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1725-1736, 2001.