Abstract: The present invention relates to a polishing cloth comprising an expanded thermoplastic resin product having a cellular structure, and an expansion ratio of 1.5-fold to 30-fold, with substantially uniform cells having an average cell diameter of 300 .mu.m or less being distributed within the cross-section of the expanded product, and with unexpanded resin phases of 0.5 .mu.m to 45 .mu.m surrounded by three or more cells, wherein the proportion of the unexpanded phases are 0.01% to 70% in terms of area ratio within the expanded product cross-section, which has excellent performance of mirror surface polishing, for example, integrated circuit substrate, disc substrate for information recording, optical lens, optical mirror, etc. The present invention particularly relates to a polishing cloth for precise polishing to a surface roughness of 100 .ANG. or less.

Abstract: An expandable fluorine-contained polymer composition comprising (A) a fluorine-contained polymer in which the ratio (tan .delta.) of dynamic loss modulus to dynamic storage modulus at a temperature 30.degree. C. higher than the melting point of the polymer ranges from 0.3 to 0.9, and (B) a blowing agent, and a foam obtained from said composition.

Abstract: A novel foam composed of closed cells having a specific tensile strength of 150 kg/cm.sup.2 or more, a compression recovery of 80% or more and a heat shrinkage of 50% or less, a variation in thickness of foam of less than 50%, a corrugation value of less than 100% and a surface smoothness of less than 2 mm, an average cell diameter of 0.05-3 mm, said foam having a foam density of 0.007-0.10 g/cm.sup.3, a variation in thickness of cell wall film of .+-.30% or less and a variation factor of cell diameter of 70% or less, obtained by foaming a composition consisting essentially of 100 parts by weight of a substantially non-crosslinked polyethylene having a density of 0.935 g/cm.sup.3 or more and a melting point of 117.degree. C. or more, 0.05-10 parts by weight of a foaming decelerant having the capability of prolonging the foaming time by at least one second as compared with the absence of the foaming decelerant, as measured by a glass tube blowing test method, and 0.001-5 parts by weight of a nucleating agent.