A comparison of tetraethylthiuram and tetramethylthiuram disulfide vulcanization. II. Reactions in rubber

Abstract

ABSTRACT:The reactions of tetraethylthiuram disulfide (TETD) with polyisoprene were investigated under vulcanization conditions. Samples of polyisoprene compounded with various combinations of TETD, sulfur, and ZnO were heated in a differential scanning calorimeter to various degrees of vulcanization. The crosslink density of the compounds was determined by swelling, and the extractable residual curatives and reaction products were analyzed with high-performance liquid chromatography. TETD caused crosslinking to occur in the absence of added sulfur, as did tetramethylthiuram disulfide (TMTD), both sulfur donors. In the presence of sulfur, the formation of TETD polysulfides occurred immediately before the crosslinking reaction started. The TETD polysulfides were the initial crosslinking agents. The ready reaction between TETD and zinc oxide to form zinc diethyldithiocarbamic acid resulted in considerably higher crosslink densities. This greater reactivity between TETD and zinc oxide, compared with that between TMTD and zinc oxide, did not lead to any noticeable differences in the vulcanizate.

One-Step Simultaneous Synthesis of an Industrially Important Rubber Accelerator and a Lubricant Additive by Disulfide Bond Contraction

“…To that end, we envisaged using triphenylphosphite (TPPi) as the P(III) source for the expected reduction. The byproduct triphenylthiophosphate (TPPT) is a versatile fine chemical for multiple applications, as it can be used as: (1) an ashless extreme pressure and antiwear additive for lubricants, grease and hydraulic fluids; 22,23 (2) a flame retardant owing to its excellent thermal stability; 24 (3) an additive to Freon refrigerant to suppress the erosion caused by Freon decomposition. 25 In an economical perspective, the consensus market prices for TMTD and TPPi are approximately $2042/t and $2219/t, respectively.…”

NMR‐Based Cross‐Link Densities in EPDM and EPDM/ULDPE Blend Materials and Correlation with Mechanical Properties

“…In this case, using sulfur-donating agents only, a stable vulcanization network with a comparably very high content of mono-and di-sulfide links is formed. [61,62] All samples were consistently prepared by hot press molding for 10 min at 190 °C.…”

Two-step continuous synthesis of tetraethylthiuram disulfide in microstructured reactors

“…Many vulcanization accelerators have been developed, including dithiocarbamates, thiurams, thiourea, thiazoles, and sulfenamides. Among them, thiurams (tetraalkyl thiuramdisulfites, TATD) (Scheme 1) can vulcanize rubber in the absence of sulfur, and are one of the most effective materials for rubber vulcanization [2]. Generally, a two-step method is used to synthesize tetraalkyl thiuram disulfides.…”

“…(1) (2) Microstructured reactors have been known as efficient reaction systems for exothermic reactions and immiscible reactions, resulting from their excellent heat and mass transfer rates [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Obvious advantages are observed in reactions, such as Michael additions of amines to α, β-unsaturated carbonyl compounds [20], the MoffattSwern oxidation [21], nitration and bromination electrophilic reactions [22], enzyme reactions [23], esterification [24], and so on.…”