Improving dimensional stability by acetylation of discrete layers within flakeboard

Extensive research has been carried out on the thickness swell (TS) behavior of different types of wood composite panels. Of particular interest, studies investigating layer TS behavior have been carried out by Wang and Winistorfer (2003, 2001, 2000), and Xu and Winistorfer (1995a and 1995b). Results from these studies clearly indicate that the majority of TS in wood composite panels, such as medium density fiberboard and oriented strandboard (OSB), occurs in the outer layers of the panel. By utilizing this knowledge, it was conceived that appreciable gains in dimensional stability could be attained by using treated furnish for specific layers within a panel. OSB manufacture typically involves the forming of a 3-layer mat, with the difference between the layers being the orientation of the strands. The technology associated with this mat-forming step lends itself well to being adapted for including layers of treated strands within the mat structure. Using treated furnish has advantages over post-pressing panel treatments; for example, post-pressing treatments would necessitate additional handling of large panels that may require significant additional space and may also provide more opportunities for panel damage. Economically, the treatment of furnish used for discrete layers has obvious advantages over treating furnish used for the entire panel.