Thiazole accelerators

Logothetis [62] describes the use of triazine accelerators in the vulcanization of nitrile and fluoro elastomers. The triazine is more effective than the thiazole accelerators and produces highly reversion-resistant vulcanizates. 

Uses. Rubber accelerator and vulcanizer, as an activator of thiazole accelerators, and as a plasticizer in neoprene pharmaceutical grade used in treatment of alcoholism... 

Studies with model compounds indicate that thiazole-accelerated cures tend to favor reactions at allylic positions. This has been explained (68MI11503) in terms of the structure of the polysulfidic intermediates which allows facile rearrangement and fragmentation reactions to occur (35). 

The thiazole accelerators promote rapid cures, but do not provide adequate processing times for many applications. Longer processing times are obtained with the sulfenamides... 

Butasdn. (Atot em N. Am.] Zinc dibu-tyldithiocarbamate accelerator for DM, latexes activator for thiazole accelerators. 

High-tensile-strength butyl compounds generally use FEF- or GPF-grade carbon blacks. Vulcanization systems tend to be based on thiazole accelerators such as mercaptobenzothiazole disulfide (MBTS) and thiuram accelerators such as tetramethylthiuram disulfide (TMTD). Low-tensile-sfrengfh compounds will use a clay or silica reinforcing filler in place of carbon black. 

NR latex, and cements, EPDM sponge compds. activates thiazole accelerators flotation collector for sulfide ores acid inhibitor intermediates synthetic organic pharmaceuticals sulfur dyes heat stabilizer for PVC in food-pkg. adhesives accelerator for food-contact rubber articles for repeated use stabilizer for food-grade polymers Regulatory FDA 21CFR 175.105, 177.2600, 178.2010... 

Esters (and thioesters. Chapter 9) confer valuable anti-wear and corrosion inhibition properties when used as oil additives. Dialkyldithiophosphates (Chapter 9.10) can be used in vulcanisation processes to reduce staining of latex products. They remove metallic cations which otherwise can form intensely coloured complexes with the thiazole accelerators which are used. 

The sodium salt (Pr 0)2PSSNa is useful as an activator of thiazole accelerators used for the low-temperature vulcanisation of rubber. Other uses of [(RO)2PS2l2Ni, for example, are as anti-oxidants in plastics (Section 12.15). Sodium and ammonium dialkylphosphoro-dilhioates (R= Et or Pr) are used as flotation agents to suspend and separate metallic ores from unwantedcontaminants. Dithiophosphinic acids, R2P(S)SH, can be used to extract Am " and Ln " from radioactive wastes [41]. 

DPG is the most commonly used member of the guanidine class of rubber accelerators. DPG is commonly used as a secondary accelerator (or kicker ) with primary sulfenamide accelerators and sometimes with thiazole accelerators as well. DPG is also a silanization accelerator. It can interact with the silica surface, which then reacts with organosilanes in tread stocks to help reduce rolling resistance. DPG is not as chemically active as the thiuram or dithiocarbamate accelerators. 

Combinations of thiuram and thiazole accelerators are commonly used in sulphur cures, especially where cost is a primary consideration and heat resistance is not. Dithiocarbamates give fast cures and good ageing properties, but as they tend to be scorchy a thiazole (MBT or MBTS) is normally used with them to provide processing safety. Sulphur-donor systems based on thiuram/dithiocarbamate combinations and containing very little or no elemental sulphur provide superior ageing properties and low compression set. 

In gum or mineral filled compounds, synthetic polyisoprenes exhibit longer times to optimum cure than natural rubber and significant differences between the various synthetic polymers are observed with some vulcanisation systems. The lack of naturally occurring amine activators present in natural rubber becomes evident in a simple thiazole-accelerated sulphur cure system. This is very well illustrated by observing the incremental addition of diphenylguanidine (DPG) to a MBT-accelerated sulphur system (Table 5) where the lack of added amine accelerator shows a very slow cure for the synthetic polymer but, if sufficient is added, the differences between the rubbers become indiscernible. 

STRUCTURAL CHARACTERIZATION BY PYROLYSIS GAS CHROMATOGRAPHY OF ETHYLENE-PROPYLENE-DIENE RUBBERS CURED WITH SULPHUR/THIAZOLE ACCELERATOR... 

Journal of Applied Polymer Science 60, No.9, 31st May 1996, p.1349-59 CURE SYNERGISM EV CARBOXYLATED NITRILE RUBBER(XNBR) VULCANISATION EV PRESENCE OFTHIOPHOSPHORYL DISULPHIDES AND AMEVE DISULPHIDE/ THIAZOLE ACCELERATORS Biswas T Basu D K... 

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