Accelerator diphenyl guanidine

Reduction of the adhesion level will occur if certain compounding ingredients are not avoided. The acceleration system has a direct effect on the adhesion level dibenzothiazole disulphide (MBTS) gives the highest adhesion levels. If a second accelerator is used, e g., tetramethyl thiuram disulphide (TMTD) or diphenyl guanidine (DPG), then the adhesion is significantly affected. Other ingredients which cause problems are plasticisers and process oils. 

The commercially important representatives of group 4 are diphenyl guanidine and diortho tolyl guanidine. Group 5 includes a number of aldehyde aniline reaction products such as formaldehyde aniline, ethyledene aniline, butraldehyde aniline, heptaldehyde aniline hexa methylenetetraamine and acet-aldehydeaniline. Aetaldehyde, butraldehyde and heptaldehyde derivatives of aromatic amines are powerful accelerators. 

Cure system species, accelerators and their reaction products This class of additive can present problems as they are often thermally labile, reactive and, in some cases, have a degree of ionic character (e.g. zinc dithiocarbamate salts). In these cases LC-MS is a more appropriate technique than GC-MS. It is also easier to use LC-MS with a number of the approved food simulants as they can be injected directly into the instrument, being compatible with the mobile phase. In some cases the reaction products (e.g. aniline from diphenyl guanidine, and benzothiazole from thiazole and sulphonamide accelerators) are stable and so GC and GC-MS can be used. Peroxides are popular curatives for food use rubbers and the stable, breakdown products of these can be easily detected by GC-MS. 

Accelerators used include hexamine, diphenyl guanidine, ethylidene aniline, mercapto-benzothiazole, dibenzothiazole disulfide, N-Cyclohexyl benzothiazole sulfenamide, sodium diethyl dithiocarbamate, tetramethylthiuram disulfide, tetraethyl thiuram disulfide, dipentamethylene thiuram tetrasulfide, sodium isopropyl xanthate, zinc butyl,... 

Thiurams and carbamates have most commonly been responsible for the type-IV reactions due to rubber gloves. Mercaptobenzothiazole was the first benzothiazole accelerator used in gloves, but other derivatives can also be used. The reports on sensitization to thiourea compounds from rubber gloves are few and, for the most part, involve gloves made of neoprene rubber which may also contain diphenyl-guanidine (Estlander et al. 1994a, 1995 Kanerva et al. 

Guanidines Diphenyl guanidine (DPG) >=< C=NH Medium-speed accelerator Now largely used in conjunction with other accelerators. Strong synergism with MBT... 

For vulcanization either amines or peroxides may be used. A typical amine is 4,4 -methylene dianiline (4,4 -diamino diphenyl methane) which is now used in conjunction with an accelerator such as diphenyl guanidine or diorthotolylguanidine. The properties of these rubbers have been reviewed (Hagman et al., 1976). 

Kodama et al. [291] have reported TG-DSC curves for the analysis of the interaction between vulcanisation accelerators (tetramethylthiuram disulfide, dibenzothiazolyl disulfide, diphenyl-guanidine and Af-cyclohexyl-2-benzothiazolylsul-fenamide) and fillers (CB, hard clay and CaCOs). The initial m.p. of the accelerators was largely influenced by the fillers. Emmott et al. [292] have investigated the complex reaction between Sr(N03)2 and the binder Alloprene (a pyrotechnic system) at about 300°C by simultaneous TG-DSC and TG-DTA-MS. The same techniques were used to examine the Ti-NaNOs-Alloprene and Mg-NaNOs-Alloprene systems [293-295]. 

Standard rubber industry accelerators (e.g., CBS, diphenyl guanidine, mercaptobenzothiazole disulfide (MBTS) and zinc diethyl carbamate these can be used with or without other rubber chemicals, such as peptisers)... 

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