ABSTRACT
This chapter explains transport properties of new membranes for industrial application that have been developed in Japan and discusses their industrial application for gas separation. It shows a comparison of the oxygen permeabilities of random copolymers with block copolymers. Many membrane researchers are devoting attention to a new polymer, poly[1-(trimethylsilyl)-1-propyne], which was first synthesized in Japan. The typical data for permeability, diffusivity, and solubility coefficients are summarized. The chapter also shows the effect of the content of poly(dimethylsiloxane) oligomer and poly[1,3,5-tris(3,3,3-trifluoropropyl)-1,3,5-trimethyl cyclotrisiloxane] on the permeability of oxygen and nitrogen. One of the main reasons for the instability of the gas permeability of PMSP membranes is considered to be an unrelaxed large excess free volume, which is very easy to reduce. For the practical use of the polyimide membranes for gas separation the most important points are producing the ultrathin active skin layer on the surface of hollow fibers, and casting hollow fibers with enough strength and flexibility for manufacturing modules.
