Sugdens parachor

Liquid surface tension is calculated using the Sugden Parachor method [242]. Neglecting vapor density, surface tension for the liquid mixture is ... 

G = superficial mass vapor velocity based on the cross-sectional area of the column, Ib/hr-sq ft M = molecular weight, Ib/lb mole N = dimensionless number P = pressure, consistent units [P] = Sugden parachor sg = specific gravity T = temperature, °F U = superficial velocity, ft/hr... 

If reliable values of the liquid and vapour density are available, the surface tension can be estimated from the Sugden parachor which can be estimated by a group contribution method, Sugden (1924). 

The surface tension is calculated starting from the parachor and the densities of the phases in equilibrium by the Sugden method (1924) J... 

S. Sugden, The Parachor and Valeny, Roudedge Sons, London, 1930. 

Table 8.7. Contribution to Sugdens s parachor for organic compounds (Sugden, 1924)...

Sugden J.G.S. cxxv. 1177, 1924 cxxvii. 1525, 1868, 1925) has compared the molecular volumes of substances under conditions such that they possess identical surface tensions and has shown that they are determined by the molecular constitutions of the substances. In obtaining the parachor P Sugden makes use of the approximate relationship between free surface energy and density noted by Macleod Trans. Farad. Soc. xix. 38, 1923) a = c(pi- p y... 

The parachor was introduced by Sugden (1924), who gave a list of atomic constants. Later the atomic and group contributions were slightly modified and improved by Mumford and Phillips (1929) and by Quayle (1953). 

Due to the fact that the extrapolation of surface tensions of melts to room temperature leads to reliable values for the solid polymer, the surface tension of solid polymers may be calculated from the parachor per structural unit by applying Eq. (8.5). The molar volume of the amorphous state has to be used, since semi-crystalline polymers usually have amorphous surfaces when prepared by cooling from the melt. We have found that the original group contributions given by Sugden show the best correspondence with experimental values for polymers. 

From Table 8.1 (Sugden s values) we obtain the following group contributions to the parachor and the molar volume ... 

Sole K (Ed), "Polymer Compatibility and Incompatibility Principles and Practice", Vol 2, MMI Symp Series, New York, 1982. Sugden S, "The Parachor and Valency , Routledge, London, 1930. 

The Rao function has the same form as the Sugden function or Molar Parachor (Ps = My1/4/p), derived by Sugden in 1924, which correlates the surface tension with the chemical structure. Also the Small function or Molar Attraction Function, which correlates the cohesion energy density, ecoh, and the solubility parameter, 8, with the chemical structure, has this form ... 

Hence, a comparison of parachors for different compounds, according to Sugden, is a comparison of molar volumes at temperatures at which the liquids have the same surface tension. 

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