Download Full PDF - 41.38 MB - The Society of Irish Foresters
Download Full PDF - 41.38 MB - The Society of Irish Foresters Download Full PDF - 41.38 MB - The Society of Irish Foresters
---------------------------------------------------------------------_ .. IRISH FORESTRY 1.40 1.20 1.10 1.00 • Pine unmodified 0.90 • P174 A P177 1.30 1.20 • Spruce unmodified • SPl -& SP2 1.10 1.00 0.90 1.30 • Larch unmodified 1.20 • Ll 1.10 1.00 0.90 0.80 +----+----+----11----+----1 1st dry 2nd dry 3rd dry 1st wet 2nd wet 3rd wet Figure 2. Swelling stability results. The vertical ordinate shows the relative volume change. 56
IRISH FORESTRY Conclusions Mechanical and physical test results obtained with the acetylated materials are broadly in line with what was expected from the European experience. The most surprising result is that increasing the degree of acetylation of the pine from 16 WPG to 19 WPG has relatively little effect on the moisture absorption behaviour. In all cases the scatter in the results was large. The scatter is thought to arise from two factors. First, the relatively coarse nature of the timber arising from the fast growth and wide ring spacing, and secondly there is the probability that the samples tested contained both heartwood and sapwood. This would affect both the response to acetylation and the subsequent response to moisture change in the acetylated materials. Despite these factors it is considered that the overall pattern of results obtained is reliable. The results from the fungal decay experiments have demonstrated the increased durability expected but the better performance of the spruce than the pine was surprising given that in the untreated condition it was less durable, and that it is regarded as less permeable to reagents. Overall the results confirm that the acetylation process offers benefit with the materials examined. It is now necessary to proceed with acetylation experiments using specimens of commercial cross-section. Acknowledgments This research was facilitated by a COFORD grant as Project 4-1-97. Evaluation of the effects of acetylation on Irish softwood. Materials were generously supplied by Palfab, Macroom, Co Cork. References Beckers, E.P.J., Militz, H. and Stevens, M . 1995. Acetylated solid wood laboratory durability tests part 2 and field trials. The International Research Group on Wood Preservation, Doc No IRG/ WP 95-40048 Beckers, E.P.J., de Meijer, M. and Militz, H. 1998. Performance of finishes on wood that is chemically modified by acetylation. Journal of Coatings Technology 70: 59-67. Birkinshaw, C. 1998. Chemically modified wood, a review with consideration of the opportunities for application to Irish timber. Irish Forestry 55(2): 21 -34. Dawson, 8 and Torr, K. 1992. Spectroscopic and colour studies on acetylated radiata pine exposed to UV and visible light. Chemical modification of lignocellulosics. Forest Research Institute, Rotorua, New Zealand, pp 41-50. Hill, c.A.S. and Jones, D. 1996. The dimensional stabilisation of Corsican pine sapwood by reaction with carboxylic acid anhydrides. Holzforschung 50: 457-462. Forster, S.c., Hale, M.D. and Williams, G. 1997. Efficacy of anhydrides as wood protection chemicals. The International Research Group on Wood Preservation, Doc. No. IRGIWP 97- 30162. Larsson, P and Tillman A-M. 1989. Acetylation of lignocellulosic materials. The International Research Group on Wood Preservation, Doc. No. IRGIWP 3516. Martins, v.A. and Banks, W.C.B. 1991. Sorptive properties of chemically modified wood. Wood Protection 1(2): 69-75. Peterson, M.D and Thomas, R.J. 1979. Protection of wood from decay fungi by acetylation - an ultrastructural and chemical study. Wood and Fiber Science 10(3): 149-163. Rowell R.M. Lichtenberg, R.S. and Larsson, P. 1993. Stability of acetylated wood to environmental change. Wood and Fiber Science 25(4): 359-364. Rowell R.M. and Ellis, W.D. 1978. Determination of the dimensional stabilisation of wood using the 57
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---------------------------------------------------------------------_ ..<br />
IRISH FORESTRY<br />
1.40<br />
1.20<br />
1.10<br />
1.00<br />
• Pine unmodified<br />
0.90 • P174 A P177<br />
1.30<br />
1.20<br />
• Spruce unmodified<br />
• SPl -& SP2<br />
1.10<br />
1.00<br />
0.90<br />
1.30 • Larch unmodified<br />
1.20<br />
• Ll<br />
1.10<br />
1.00<br />
0.90<br />
0.80 +----+----+----11----+----1<br />
1st dry 2nd dry 3rd dry<br />
1st wet 2nd wet 3rd wet<br />
Figure 2. Swelling stability results. <strong>The</strong> vertical ordinate shows the relative volume<br />
change.<br />
56
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