The term “sulphur donor” is commonly used to refer to organic disulphides and higher sulphides that can actively provide sulfur during the vulcanization process, thereby creating sulphidic crosslinks. Sulphur donors can be categorized into two types: those that directly substitute free sulfur without significant changes in vulcanization characteristics, and those that simultaneously act as vulcanization accelerators.

Examples of the first type of sulphur donors include dithiomorpholine (DTDM) and caprolactam disulphide (CLD). Examples of the second category, which act as both sulphur donors and accelerators, include 2-morpholinodithiobenzothiazole (MBSS), dipentamethylenethiuram-tetrasulfide (DPTT), N-oxyethylene-N’-oxyethylenethiocarbamyl sulphenamide (OTOS), tetramethylthiuram disulfide (TMTD), and its analogues. The chemical structures of these sulphur donors are depicted in figure:

In response to the demand for N-nitrosamine-free sulphur donors, tetrabenzylthiuram disulfide (TBzTD in figure) has been introduced. While TBzTD primarily functions as a secondary accelerator, it can also serve as a sulphur donor at higher loadings.

Additional materials are available that can act as sulphur donors. Examples include alkyl phenol polysulfide, bis(3-triethoxy silyl propyl) tetrasulfide (TESPT) and dialkyl dithiophosphate polysulfide.