Estimation of the surface energy of chemically and oxygen plasma-treated regenerated cellulosic fabrics using various calculation models

The aim of this work was to evaluate and compare the surface energies (SFEs) of regenerated cellulose fabrics modified by washing, bleaching, conventional chemical treatment (slack-mercerization), and plasma treatment. Three commonly used methods of estimating apolar, polar, and acid/base contributions were applied: geometric mean (GM), using diiodomethane (MI) and water as probes; van Oss-Good-Chaudhury (vOGC), using MI, tetrahydrofuran (THF), and chloroform (CF); and Owens-Wendt-Rabel-Kaelble (OW), using water, MI, THF, CF, ethanol and ethylene glycol. All treatments gave rise to more hydrophilic materials, as indicated by a decrease in the water contact angle. The GM and OW methods both showed that the polar component of the SFE increased after bleaching or conventional chemical treatment and, in particular, after plasma treatment. The vOGC method showed much smaller effects and indicated decreasing polarity after plasma treatment. This was probably due to the use of acid and base probes that did not contain hydroxyl groups in the determination of vOGC parameters, that is, the effect of the treatments was to introduce acid functionalities that could interact strongly with hydroxyls (hydrogen bonding) but not with the Lewis base THF or Lewis acid CF.