Surface Energy of Extracted and Non-extracted Norway Spruce Wood Particles Studied by Inverse Gas Chromatography (IGC)

The surface energy of extracted and nonextracted Norway spruce wood particles was studied by means of inverse gas chromatography (IGC). The measurements were performed at infinite-dilution, using a series of dispersive n-alkanes and Lewis acid-base probes. Results from the n-alkane series indicate that the removal of extractives from the spruce wood particles increases their Lifshitz-van der Waals (dispersive) surface free energy component. The interaction process between the acid-base probes and the wood particles is complex and complicates the IGC analysis. The acid-base characteristics are interpreted by comparing the specific interaction between the acid-base probes and the different wood particles at one single temperature. This analysis indicates that the extraction of the spruce wood particles results primarily in increased interaction with predominantly Lewis base probes. In contrast, the extraction results primarily in decreased interaction with predominantly Lewis acid probes. Hence, it is indicated that the wood substance without extractives exhibits greater acidic (electron-accepting) character and less basic (electron-donating) character, than wood substance containing extractives