Inverse gas chromatography and XPS of extracted kraft pulps

Abstract

Kraft pulps at the kappa number level of 15 obtained from Acer saccharum (sugar maple) and Eucalyptus globulus prepared with and without hot water pre-extraction (HWE) were analysed by inverse gas chromatography (IGC) and X-ray photoelectron spectroscopy (XPS). In the case of A. saccharum pulps, the dispersive component of the surface energy (γsd) at 40ºC determined by IGC was 39.8 mJ m-2 (control pulp without HWE) and 36.7 mJ m-2 (HWE pulp). E. globulus pulps resulted in γsd values of 30.8 mJ m-2 (control) and 34.9 mJ m-2 (HWE). The higher values of γsd for sugar maple pulps were interpreted as the influence of lower amounts of extractives and lignin at their surface, as revealed by XPS. It is also discussed why the acid-base character of the sugar maple pulp surface was slightly reduced with previous hot water extraction while for E. globulus it was greatly enhanced.