Sulfur Linkage in Vulcanized Rubbers

Abstract

Hill, N. J. * •¥ Methyl iodide reaction at room temperature can be used to differentiate between mercaptan, sulfide, and disulfide sulfur in anhydrous systems? Mercaptans react slowly to give hydrogen iodide. Sulfides react ^QantitatiJ^ly in 1-3 days, but the product depends on the type of residue on the sulfur atom. Disulfides react very slowly; the sulfur-to-sulfur link is ruptured with liberation of free iodine. Mercuric iodide catalyzes the sulfide and disulfide reactions, making the former quantitative in 1 hour and the latter in 3 days. Pale crepe rubber or GR-S does not interfere chemically with the reactions. The reactions are presented here with a view to their use in the determination of the sulfur linkage in vulcanizates.

Chemical recycling of sulfur-cured natural rubber using supercritical carbon dioxide

“…21,22 This vulcanizate (B-30) was scarcely devulcanized to give little sol fraction under the optimum conditions. The NR vulcanizate with predominately mono-sulfidic linkages tends to resist the devulcanization.…”

Some investigations on structure‐property relationship in XNBR vulcanizates in the presence of bis(diisopropyl thiophosphoryl) disulfide

“…izate is due to early reactions of carboxyl groups. The optimum cure time value (t 90 ) of mix A is the Treatment of the Vulcanizates with Methyl Iodide lowest among all the mixes presented in Table II, which once again indicates that the overall reac-Methyl iodide breaks the various sulfidic links [8][9][10][11][12] of XNBR vulcanizates while the ionic crosslinks tion between zinc oxide and XNBR is very sharp 3 as also evident from curve A, Figure 1. remain unaffected.…”

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

“…To begin with, the dual system of accelerators comprising DIPDIS and OBTS was studied. The relevant cure and physical data are presented in Table 6 5 Rheographs of mixes 1 and 6-9 (Table 11) I1 (mixes 1, [14][15][16][17]. The course of vulcanization is recorded in the corresponding cure curves as shown in Figure 4.…”

“…We found earlier' that the vulcanizates of XNBR, derived from bis(dicyclohexy1)thiophosphoryl disulfide (DCHDIS) and DIBDIS provide notable mechanical properties among the various thiophosphoryl disulfides studied so far. Therefore, it was decided to investigate the effect of the binary sys- Table I1 (mixes 14, [18][19][20][21][22][23][24][25]. Relevant cure and physical data are also given in Table 11.…”

“…Vulcanizates obtained from XNBR are resistant to heat and oxidation due to the presence of metallo- Rheographs of mixes 1 and [14][15][16][17] (Table 11) Rheographs of mixes 14 and 18-21 (Table 11) 11. As expected modulus values of all the vulcanizates increased and the values of elongation at break decreased.24s28*29 DIPDIS-accelerated XNBR vulcanizate shows over 88% retention of its original tensile value (mix 1).…”