Surface energy of extracted and non-extracted Norway spruce wood particlesstudied by inverse gas chromatography (IGC)

The surface energy of extracted and nonextracted Norway spruce wood particl es was studied by means of inverse gas chromatography (IGC). The measuremen ts were performed at infinite-dilution. using a series of dispersive n-alka nes and Lewis acid-base probes. Results from the n-alkane series indicate t hat the removal of extractives from the spruce wood particles increases the ir Lifshitz-van der Waals (dispersive) surface free energy component. The i nteraction process between the acid-base probes and the wood particles is c omplex and complicates the IGC analysis. The acid-base characteristics are interpreted by comparing the specific interaction between the acid-base pro bes and the different wood particles at one single temperature. This analys is indicates that the extraction of the spruce wood particles results prima rily in increased interaction with predominantly Lewis base probes. In cont rast, the extraction results primarily in decreased interaction with predom inantly Lewis acid probes. Hence, it is indicated that the wood substance w ithout extractives exhibits greater acidic (electron-accepting) character a nd less basic (electron-donating) character, than wood substance containing extractives.