METHOD OF MAKING EXPANDABLE POLYSTYRENE BEADS

摘要

METHOD OF MAKING EXPANDABLE POLYSTYRENE BEADS Expandable-polystyrene beads suitable for use in making impervious containers are made from a recipe including styrene, free-radical initiator and polyvinyl pyrrolidone, and this practice includes a step of washing the beads in a warm aqueous solution to which an alkoxylated nonionic surfactant having 70-90 percent of its molecular weight accounted for by oxyethylene units is added in an amount effective to cause the washing to remove contaminating grafted polyvinyl pyrrolidone from the surface of the beads and cause them to become expandable into impervious product containers.