Polysulfide elastomers are condensation products of sodium polysulfides and dichloro compounds, such as ethylene dichloride. More complex chlorinated hydrocarbons yield products with improved properties. These elastomers are highly resistant to oils, solvents, and weathering and are found in coatings, caulking compounds, adhesives, and mechanical components. In most applications of the polysulfide rubbers, occupational health problems are related to contact dermatitis.
Basically, polysulfide rubbers are chemically saturated polymers with reactive terminals through which conversion to a thermoset, elastomeric state can be effected by means of suitable catalysts or curing agents. More specifically, these rubbers are the products of a condensation polymerization in which one or more organic dihalides are reacted with an aqueous solution of sodium polysulfide.
Polysulfide rubbers are novel in that they are available not only as solids but also as liquids. The liquids are 100% polymer, unadulterated with solvents or diluents, which also can be converted to highly elastic rubbers with properties closely approaching those of the cured, solid polysulfides. Viscosities range from a very fluid 5 poise to a heavy molasses-like 700 poise.
Design with both polysulfide crudes and liquids is quite similar, but because of the difference in physical form, the products made from these materials are processed and fabricated somewhat differently.
