Owens and Wendt equation

The geometric-mean approach has been in constant use for more than three decades, even though many articles have been published proving it to be incorrect. The Owens and Wendt equation falsely predicts ethanol and acetone to be as immiscible in water as benzene The main problem is the incorrect assumption that all polar materials interact with all other polar materials as a function of their internal polar cohesive forces. That is... 

This method utilizes a similar approach to Owens and Wendt s method but uses a harmonic-mean equation to sum the dispersion and polar contributions. Wu reported that the Owens and Wendt equation was giving surface tension values for polymers in error by as much as 50-100% when compared with their melt values, particularly for polar polymers. He suggested that a harmonic (or reciprocal) mean approximation might be better for polar polymers as given ... 

Considering ten different polymeric sohds (PS, PE, PET, PMMA, PVC, etc.) he found that the /-parameter is proportional to a polar surface tension component of the liquid but he states that it is possibly a complex function of the polar contributions to the surface tension from both liquids and sohds. There is also some scatter in these plots and he does not propose the simple square root expression adopted by Owens and Wendt (Equation 3.22b). Similar results were presented with the same method by others as well (Schultz et al, 1977a,b) who used it to determine the surface energy components of high... 

Water was chosen as a polar, and di-iodomethane as a non-polar liquid to compare the surface properties of the hybrid polymer layers containing different commercially available long chain perfluoroalkyl silanes (1 mol% each) with those of other surfaces. The measured contact angles and the surface energy data of the solids calculated according to the Owens and Wendt equation [24] are given in Table 6.3. The increase in the contact angles as a measure for a clearly reduced wettability can be observed with both test substances. 

---

See also in sourсe #XX -- [ , ]

---