Over the last 50 years interest has been growing in the use of wetting studies of real polymeric products such as coatings, fibers and porous materials to understand the interfacial phenomena. For example, hollow fiber membranes made from different materials have been used in contact with the human blood. But the contact phenomena between polymeric materials and bodily fluids are not well understood at present. The calculation of the interfacial energy, γ_(sv), could help to develop a theory of blood compatibility. However, it is acknowledged that this approach is not free of problems. All calculations of the γ_(sv) use the YOUNG-DUPRE-equation. Both Young's contact angle approach and Dupre's concept of the work of adhesion are based on rigorous thermodynamics and therefore these models require Young's equilibrium contact angle θ_e which depends only on the interfacial tension of the involved phase boundaries. In almost all measurements of real solids however, instead of θ_e the so-called contact angle hysteresis Δθ - the advancing or recently advanced angle θ_a as upper value of the Δθ and the recently retreated angle θ_r as the lower limitation can be observed. The literature presents some theoretical interpretations of the hysteresis phenomena /1 /. But there is no model to calculate θ_e by means of measurable data. Applying a new quantitative empirical approach the calculation of θ_e was presented by means of θ_a- and θ_r-values as produced by roughness variation and measured on pure paraffin wax with different test liquids /2/. Is it possible to characterize the polyolefin family or even more complex polymers in the same manner? Answering this question is the aim of the presentation.
展开▼
