Permeation of oxygen and nitrogen gases through novel polyurethane films

The permeability of oxygen and nitrogen gases through eight kinds of polyurethane films was investigated. These polyurethanes were prepared from dihydroxy compounds such as 2-methyl-2-dimethylaminomethyl-1,3-propanediol, its dimeric condensate, its polymeric condensate, 2,6-pyridinedimethanol, and phenoldiethanolamine, and diisocyanate compounds such as hexamethylene-1,6-diisocyanate and diphenylmethane-4,4′-diisocyanate. Typical permeability coefficients (P) of oxygen and nitrogen through poly(2-methyl-2-dimethylaminomethyl-1, 3-propylenehexamethylenecarbamate) at 25°C were 8.6×10-12 and 1.3×10-12 cm3(STP) cm(cm2 s cmHg)-1, respectively. The contributions of the diffusion coefficient (D) and solubility coefficient (S) on PO2/PN2 permselectivity, which were determined by the time lag method, were 67 and 33%, respectively.