Abstract: Expanded particles obtained by a method including the steps of: providing unexpanded particles formed of a polyethylene resin; impregnating the unexpanded particles with a liquid containing a polymerizable monomer including an acrylic monomer, and optionally a styrenic monomer; subjecting the impregnated polymerizable monomer to polymerization conditions so that at least a portion of the polymerizable monomer is grafted on the polyethylene resin to obtain modified polyethylene particles; and subjecting the modified polyethylene particles to an expansion treatment. Further expansion of the expanded particles within a mold gives a foamed article suitable for use as a consumable pattern in full mold casting.