Preparation of hollow spherical articles

A novel method for making hollow articles in spherical and other shapes is outlined. These spheres are prepared by dissolving a film-forming polymer in a sublimable core solvent, shaping the blend while molten, cooling to solidify, and subsequently removing the solid core material as a vapour. The film-forming solid migrates to form a shell having the original core shape and a honeycomb-like porous wall. Inorganic hollow objects can also be made by introducing sinterable solids to the hot solution, subsequently heating to remove the organic portion and further heating to effect sintering. Size, strength, wall thickness, bulk density and surface characteristics can be controlled to suit the end use.