Thiokol permeability

Thiokol elastomers possess fairly low tensile and tear properties. However, they have excellent resistance to both aliphatic and aromatic solvents at room temperature and slightly elevated temperatures. The Thiokol division of Morton International Corporation is the supplier of polysulfide elastomers in the United States. It is estimated that 1360—1600 t are used annually in the United States. The primary use of polysulfide is in seals, gaskets, rolls, and diaphragms where solvent resistance and low permeability are useful. 

A typical thiokol with 60 parts carbon black per 100 of polymer has a tensile strength of 1200 Ibf/in., an elongation of 300%, a specific gravity of 1.25, and a Shore A hardness of 68. Thiokol has excellent resistance to ozone (O3) and ultraviolet radiation. It has a low permeability to solvents, such as gasoline esters, such as ethyl acetate and ketones, such as acetone. 

Morton Thiokol, Inc. markets a series of liquid polysulfides that can be oxidized to rubbers. These rubbers have excellent resistance to most solvents, good water and ozone resistance, very low specific permeability to many highly volatile solvents and gases, objectionable odor, poor physical properties, and a service temperature range of -55 to 150°C. 

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