Reaction of Wood with Other Noncyclic Anhydrides

2 Reaction of Wood with Other Noncyclic Anhydrides 

Li etal. (2000b) investigated the reaction of wood with acetic, propionic, butyric, isobutyric or hexanoic anhydrides. The pre-extracted samples were vacuum impregnated 

Wood Modification Chemical, Thermal and Other Processes C. Hill 2006 John Wiley Sons, Ltd 

Li etal. (2000a, 2001b) smdied the flammability of wood modified with acetic or propionic anhydrides, finding that this parameter, as determined by limiting oxygen index (LOI), was the same as that found for unmodified wood. Samples were also prepared which were impregnated with sodium silicate prior to anhydride modification. The latter treatment resulted in a decrease in flammability, as shown by an increase in the LOI of the wood. 

As noted previously in Chapter 3, the improved dimensional stability of wood as a result of anhydride modification has been found to be a function of WPG only, irrespective of the anhydride used for modification (Stamm and Tarkow, 1947 Hill and Jones, 1996b Li etal., 2000b). This shows that improved dimensional stability arises due to a bulking phenomenon, caused by the volume occupied by the bonded acyl adducts in the cell wall. The dimensional stabilization of wood modified with crotonic anhydride has also been reported ( etin and Ozmen, 2001). Reductions in the EMC have also been attributed to a bulking phenomenon (Papadopoulos and Hill, 2003), and in at least one example of decay protection (Papadopoulos and Hill, 2002). Further research is needed to determine if this is the case for resistance to other decay organisms. Only with the phenomenon of surface wettability does the relationship between a physical property of chemically modified wood and WPG seem to be broken (Hill and Jones, 1996c) (Table 4.1). 

---