Theses and Dissertations Collection

As a natural antimicrobial compound, chitosan (C) has been widely explored for wood protection against numerous deteriorating organisms and has proven its effectiveness. However, the application of chitosan as a biobased preservative has been significantly limited due to its high leachability from treated wood. Genipin is a biobased crosslinking agent that can crosslink with chitosan in very mild conditions. The objective of this study was to examine the decay resistance and leachability of genipin-crosslinked chitosan (GC) treated wood against common wood-decaying fungi. The formation of GC was confirmed using Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). The antifungal efficacy of GC against two brown-rot fungi, Gloeophyllum trabeum (G.t.) and Rhodonia placenta (R.p.) and two white-rot fungi, Trametes versicolor (T.v.) and Irpex lacteus (I.l.) was first determined using malt-gar as substrate, which revealed that GC inhibited the growth of all fungi studied and exhibited similar efficacy to those of C treatment levels. Micrographs from the light and fluorescence microscopy showed changes in fungi morphology and nuclei deformation due to the effect of GC. Upon impregnation, GC-treated wood samples show an increased retention and mass gain as the function of treating concentrations, which were as high as 21 kg/m2 and 3.6%, representatively. However, cross-linking chitosan with genipin did not reduce the leaching rate of chitosan. GC treated wood samples generally show a significantly lower mass loss than those of the control groups regardless of the leaching test.