INITIAL DENSITY DEPENDENCE OF GAS VISCOSITY'S

The gas viscosity depends on pressure or density and was expressed as a sum of the viscosity which arose from the egect of molecular association and that which was caused from the egect of transfer of the momentum by the mole-cularcollision. The initial density dependence ofgas viscosity,d-y-_,(~/Bp)rw was obtained from the experimental viscosity values and was compared with the theoretically calculated d-values, where A is viscosity of gas; p density; and v, [he viscosity extrapolated to zero density. For a nonpolar gas, the experimental d-values were obtained from the viscosity data of eleven kinds of gases. The effect of molecular association on [he gas viscosity was slight, and the contribution from collisional transfer was correlated by use of T•, where T'-T/ek-t; T is absolute temperature; a the potential parameter; and k the Boltzman constant. The improved m'-values were in better agreement with the experimental ones than the original theoretical ones. For a polar gas, the experimental dwalues were obtained from the vis-cosity data of NA2, 502, A20, and three hydrocarbon halides. The effect of molecular association on the gas viscosity was eatremely larger than that of a nonpolar gas. The theoretically calculated d-values were mrrnlnted by use of the polazity parameter, d. The improved s'-values were in good agreement with the experimental ones except H2O