Legislation restricted the continued use of chromate copper arsenate (CCA) preservatives and creosote. Hence, wood protection agents using different fixation systems were brought forward or were developed as well as new environmental friendly solutions were investigated. Earlier investigations attributed an antimicrobial effect to chitosan. Chitosan is a derivative of the natural amino polysaccharide chitin and it is produced from the exoskeleton of crustacean. For a reliable wood protection a concentration of 5% chitosan is needed, which raises the cost of the end product. Previous studies display synergistic effects between chitosan and different wood protection agents. The current work investigates the amount of chitosan and wood protection agent needed in order to gain synergistic effects. Furthermore, the influence of the quality of chitosan on the synergistic effect is evaluated.
Wooden samples treated with the various chitosan-wood-preservative-combinations were leached according to EN 84. After leaching, the samples were exposed to Coniophora puteana in a modified EN 113 test for eight weeks. An anti-fungal effect could be seen for the leached chitosan products. However, none of the chitosan treated wood samples reached a mass loss below 3%. Mixing chitosan with the wood protection agent boron, copper or the wood presevatie Scanimp leads to different results between the combinations. Low amounts of chitosan and Scanimp showed an improved protection compared to Scanimp alone. Synergistic effects between boron-chitosan- and copper-chitosan combinations could not be detected.
Keywords: chitosan, boron, copper, Scanimp, leaching test, fungal decay test
Authors
Witt B.
Department of Wood Science and Technology, University of Hamburg
Treu A.
Department of Wood Technology, Norwegian Forest and Landscape Institute, Ås
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