Abstract: The present invention concerns a method for production of foams of thermoplastic polymer such as polyethylene, polypropylene, polystyrene, polyvinyl chloride. More specifically its goal is a method for production of thermoplastic foams comprising a premixing step of at least a thermoplastic polymer in the form of a divided solid with at least an ester of azocarboxylic acid.

Abstract: The invention relates to supported ligands and catalysts for use in the polymerization of olefinically unsaturated monomers such as vinylic monomers, comprising the use of a compound attached to support, the compound being capable of complexing with a transitional metal. Preferably the compound capable of complexing with a transition metal is a diimine such as a 1,4-diaza-1,3-butadiene, a 2-pyridinecarbaldehyde imine, an oxazolidone or a quinoline carbaldeyde. Preferably the catalysts are used in conjunction with an initiator comprising a homolytically cleavable bond with a halogen atom. The application also discloses processes for attaching ligands to supports, and processes for using the catalysts disclosed in the application.