Acetylated wood density

Imamura, Y. Nishimoto, K., Yoshida, Y., Kawai, S., Sato, T. and Nakaji, M. (1986). Production technology for acetylated low-density particleboard II. Decay and termite resistance. Wood... 

Rowell, R.M., Imamura, Y., Kawai, S. and Norimoto, M. (1989). Dimensional stability, decay resistance, and mechanical properties of veneer-faced low-density particleboards made from acetylated wood. Wood and Fiber Science, 21(1), 67-79. 

Density. Acetylated wood is more dense than untreated wood and has fewer fibers of lignocellulose per unit volume (47). This effect is caused by the bulking of the acetate, which is more dense than water. Wood usually gets slightly darker after acetylation with uncatalyzed acetic anhydride it also loses much of its natural brilliance... 

USDA, Forest Service, Forest Products Laboratory, FPL GTR-55 Rowell RM, Imamura Y, Kowai S and Norimoto M (1989) Dimensional stability, decay resistance and mechanical properties of veneer faced low-density particlehoards made from acetylated wood. Wood and Fiber Science, 27(1)67-79 Rowell RM, Kawai S and Inone M (1995) Dimensionally stabilized, very low density fibreboard. Wood and Fiber Science, 27(4) 428-36 Rozsa AN (1994) Dielectric vacuum drying of hardwood. Proceedings 4th lUFRO International Drying Conference, Rotorua, New Zealand, 271-8 Ruddick JNR (1987) Proceeding of the incising workshop, Richmond, British Colombia, 1986. Special Publication 28. Forinteck Canada Corp., Vancouver, BC... 

The production of MDF from allylated wood fibres has also been reported (Ogawa and Ohkoshi, 1997). The IBS of the 4 mm thick boards was superior to control boards (unmodified fibres bonded with PF resin), provided that the temperature of the allylation reaction and board density was sufficiently high. The MOR was markedly inferior to that of control boards in all cases (c. 10 MPa for allylated compared with c. 60 MPa for controls, at a board density of 800 kg m ). Blending of the allylated fibres with acetylated fibres caused a decrease in IBS, but did not affect MOR. It is perhaps significant that no free-radical initiator was used during hot-pressing in either study, which may account for the lack of reactivity of the allylated surfaces. 

Limited tests on strength properties of wood acetylated with thioacetic acid showed that MOR in static bending, impact strength, maximum crushing strength in compression and density improved. It is, therefore, evident that thioacetic acid has either no adverse effect on wood components and their interlinks or the improvements affected by modification far exceed these effects, so as to be of little consequence and ending in net gains. 

Property enhancement by acetylation has been frequently reported over the years in other reconstituted wood products such as flakeboards, particleboards, and fiberboards [8,9,11,12,59-64]. Table 16 shows the laboratory decay test of low-density acetylated particleboards made from perishable albizzia wood. They were resistant to attack by Tyromyces palustris (brown rot), Coriolus versicolor (white rot), and Chaetomium globosum (soft rot) above 12% WPG. These acetylated boards with 20% WPG also exhibited an improved resistance to attack by the destructive Formosan termite, Coptotermes formosanus, in the laboratory. However, their performance was unsatisfactory in the wet tropics with a higher hazard of termite attack. High resistance to fungal and bacterial attack in acetylated southern pine and aspen flakeboards was evidenced in laboratory and fungus cellar tests [12]. 

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