Bis(diisopropyl)thiophosphoryl sulfides in vulcanization reactions

Abstract

SynopsisA synergistic combination of bis(diisopropy1)thiophosphoryl disulfide, dimorpholyl disulfide, and sulfur is used to produce an efficient vulcanizing system for a range of rubbers. This produces vulcanizates with the exceptional thermal and thermal-oxidative stability characteristic of sulfur donor vulcanizates and the rapid and extensive crosslinking reaction normally associated with a conventional sulfur-accelerator combination. A pronounced induction period is noted. The crosslinks initially produced in cis-1,4-polyisoprene rubbers are predominantly polysulfide but reduce to mono-and disulfides at optimum and extended cures. The crosslinks of the ethylene-propylene terpolymer and the styrene-butadiene vulcanizates are initially mainly disulfide but are rapidly reduced to monosulfides at the high curing temperatures (180°C) used. A comparison with vulcanization systems based on tetramethyltbiuram disulfide and bis(diisopropy1)thiophosphoryl triand tetrasulfides as sulfur donors and with a conventional cyclohexylbenthiazyl-2-sulfenamide-sulfur combination, respectively, shows it to have distinct advantages.

Formulation and curing characteristics of EPDM/NR and EPDM/SBR polyblends used in metallic surfaces rubber lining

“…In this modified cure system, in addition to using MBT and ZDEC, a third accelerator, tetramethylthiuram disulfide (TMTD), which is from the thiuram group, was used. The reason for using three different types of accelerators was to get a synergism effect for increasing the cure rate 18, 19. In the optimum formulation, 1.5 phr MBT, 1.5 phr ZDEC, and 1.8 phr TMTD were used.…”

“…The reason for using three different types of accelerators was to get a synergism effect for increasing the cure rate. 18,19 In the optimum formulation, 1.5 phr MBT, 1.5 phr ZDEC, and 1.8 phr TMTD were used. One of the objectives of this work was to increase the efficiency of the curing system and reduce the t 90 for EPDM/NR and EPDM/SBR polyblend samples.…”

Thiophosphoryl disulfides as crosslinking agents for chloroprene rubber

“…Apart from taking a direct role as a crosslinker, it acted as the accelerator for sulfur vulcanization, compensating for some evil effects arising from oxidative degradation by the introduction of sulfur crosslinks in the modified CR backbone (due to diene–triene transformation). Furthermore, it can act as an antioxidant,15, 16 obviously providing protection against the degenerative process…”

Cure synergism in XNBR vulcanization in presence of thiophosphoryl disulfides and amine disulfide/thiazole accelerators

“…It is now an established fact that DIPDIS acts as a sulfur donor at 160°C. '~z~z5 Additional sulfur, apart The resultant effect is the enhancement of tensile strength values for all the combinations belonging to this system (mixes [11][12][13].…”