Gas phase polymerization of vinylpolybutadiene

A process for the preparation of a 1,2-vinyl-polybutadiene with an adjustable amount of vinyl linkages in the microstructure of the polymer which comprises polymerizing 1,3-butadiene in a gas phase reactor under polymerization conditions using an inert gas in the presence of a catalyst comprising: (a) a cobalt compound; (b) a compound selected from the group consisting of a phosphine, a xanthogen, a thiocyanide, a carbon disulfide, and mixtures thereof; and (c) an organoaluminum compound, and optionally a modifier (d) can be included in the catalyst composition. There is also provided a novel resin particle prepared by the process.