Abstract: A method of vulcanizing a tubular article by extruding a sheath of unoriented polyethylene terephthalate about the article followed by quenching the sheath to an amorphous state. The sheathed article is then subjected to vulcanizing conditions in order to convert the sheath from the low density amorphous state to the higher density crystalline state, thus compressing the article to effect a smooth finish.

Abstract: A flexible endless belt track for a track-driven vehicle, said belt track having an outer ground-contacting surface to provide traction and an opposite inner surface which is adapted for moving contact with rigid elements of the vehicle drive means and the belt track supporting means, said inner surface including at least one surface portion of elastomeric material comprised of at least one vulcanized rubbery composition, said rubbery composition comprised of (A) from about 10 to about 35 parts of at least one polybutadiene polymer having a total 1,4 content of from about 80% to 100%, a cis 1,4 content of at least 10% and a combined cis 1,4 plus 1,2 content of at least 30% and (B) from about 65 to about 95 parts of two different rubbery polymer, said parts being by weight per 100 parts of (A) plus (B) and 10 to 35 parts of molybdenum disulfide and 3 to 7 parts of a mercaptosilicone or a mercaptosilane, said surface portion being adapted to come into direct moving contact with said rigid elements.