Abstract: An inexpensive yet reliable method for incorporating a minor fraction of a percent by weight of nucleating agent in a propylene polymer is provided in which the nucleating agent is dissolved at a concentration of less than 10% in a homogeneous, alcohol-based, carrier liquid having a normal boiling point of not over about 120.degree. C. The resultant solution is atomized into a full jet spray of fine droplets which is directed with full and even coverage onto a loose pulverulent bed of propylene polymer powder over a period of time and with sufficient agitation of said bed to expose essentially all segments of the bed to direct contact with said spray.

Abstract: In the process disclosed herein, a latex comprising a diene rubber pregrafted with styrene/acrylonitrile type monomer mixtures, for example, about 5 to 50% by weight styrene/acrylonitrile emulsion-grafted thereon, is added to an aqueous solution of suspending agent. Additional styrene/acrylonitrile type monomers are then added to the dispersion and polymerized onto the suspended rubbery particles with peroxide initiator to produce ABS type polymers containing from about 3 to less than about 30 percent by weight diene rubber.