Abstract: A method for producing manufactured articles made of composite material comprising the steps of: First completely filling a mold with granules of a pre-expanded polymer in granular form, selected from the group consisting of polystyrene, polypropylene, copolymer of polyphenylene oxide and polystyrene and mixtures thereof; subsequently injecting in the mold an isocyanate mixed with a compound possessing active hydrogen whereby they are filled in void spaces among the granules; and condensing said isocyanate with said compound possessing active hydrogen to yield a polyurethane foam which, by expanding, subsequently completely fills the spaces among the pre-expanded polymer granules.