New method of analysis of the surface free energy of polymeric materials calculated with Owens-Wendt and Neumann methods

A new method of analysis of differences in the surface free energy (SFE) values of a solid, calculated using the methods of Owens-Wendt (OW) and Neumann and two measuring liquids, water and diiodomethane, is presented. The concept of the analysis bases on the differences in SFE, which occur objectively and regardless of both the precision and the performing conditions of the contact angle (CA) measurements. These differences result from utilizing of different mathematical relations between CA and SFE in each of the methods. The results obtained with these two methods are compared with one another over the SFE range common for polymeric materials (20-50 mJ/m2). It is calculated that the relative difference in SFE between the results from the OW and Neumann methods can reach 19.9 % over this range.