Sulfur monochloride crosslinker

The blend of EPDM and polyacetylene was crosslinked using sulfur monochloride in a toluene solution. It should be noted that the crosslinked blend could not be doped with iodine. 

Samples containing more than 2% of sulfur did not pick up any iodine even after a 72-hour period. The completely saturated EPDM portions of the blend seem to prevent any iodine molecules from permeating into the polyacetylene moieties. In order to circumvent this problem, we have doped the blend with iodine prior to the crosslinking procedure. Subsequently, the doped material having a conductivity of 60 ft-1 cm-1 was reacted with sulfur monochloride in a toluene solution for 10 minutes. The color of the solution turned from pale yellow to dark red while the polymer film remained insoluble in the toluene solution. 

The films could be crosslinked either by treatment with sulfur monochloride in toluene solution, or by irradiation under vacuum. The chemically crosslinked film could not be doped with iodine. However, the radiation-crosslinked film could be doped with iodine, resulting in a product with conductivity as high as 10/Q mm. IR analysis suggested that only the EPDM in the blends was crosslinked by irradiation. 

WO produced from sulfur monochloride is white WO, which is more likely to be used as erasers than as a rubber compounding ingredient. This is because any residual acidity from the sulfur chloride vulcanization retards the sulfur cure of the rubber compound. Instead, the brown WO products, which are crosslinked with elemental sulfur, are commonly used as rubber compounding ingredients because they have less effect on the cure rate of the rubber compound. 

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