Ceramics-Silikáty 53, (2) 141 - 143 (2009)

The composition of the commercially produced E-glass was approximated by the five component system MgO-CaO-B₂O₃-Al₂O₃- SiO₂. Ten additional glass compositions were derived from the mean composition by two-level scheme consisting in shifting the content of each particular oxide of definite positive and negative value preserving the mutual molar ratio of remaining oxides. The surface tension was measured by the sessile drop method using the melt density value obtained by independent experiment. The profile of sessile drop was analyzed by nonlinear regression using the numerical integration of Laplace’s equation. The results were compared with the approximate formula proposed by Dorsey for large drops. The Dorsey’s formula results were about 6% higher than the results of the drop full profile analysis. The additive linear model was proposed describing the compositional dependence of the surface tension with the standard deviation of approximation of 10 mN/m.