ACCELERATORS: DEFINITION & CLASSIFICATION
•An accelerator is defined as the chemical added into a rubber compound to increase the speed of vulcanization and to permit vulcanization to proceed at lower temperature and with greater efficiency.
•Accelerator also Decreases the Quantity of Sulphur necessary for vulcanization thus improving 'aged' properties of the rubber vulcanizates.
•Over 150 different chemicals belonging to different classes of composition are known to function as accelerators for rubber vulcanizates of which around 50 accelerators are most commonly used by the Rubber Industry.
•The accelerators are generally classified as follows :
Chemical Composition Accelerators Vulcanisation Speed
Aldehyde Amines BA, HMT Slow
Guanidines DPG, DOTG Slow
Thiazoles ZMBT, MBT, MBTS Moderate
Thiophosphates ZDBP Semi-Fast
Sulphenamides CBS, TBBS, MBS Fast (delayed action)
Thioureas ETU, DPTU, DBTU Fast
Thiurams TMTM, TMTD, TETD, DPTT Very Fast
Dithiocarbamates ZDEC, ZDMC, ZDBC Very Fast
