Maleic anhydride (MA) is a cyclic anhydride which can form an ester bond with wood constituents. Previous studies showed that maleated wood improved dimensional stability and fungal resistance (Matsuda et al. 1988; Itoh et al. 1998). The weight gain through treatment was, however, lost during wet-dry cycling (Matsuda et al. 1988; Iwamoto and Itoh 2005), which indicated that the ester bonds in maleated wood is susceptible to hydrolysis. To use MA treated wood, it is required to find the way to stabilise the ester-bond. In studies of cotton cellulose, sodium hypophosphite (SHP) was suggested to form cross-links between maleated cellulose by reacting with an unsaturated carbon in adjacent maleated cellulose, resulting in enhanced wrinkle resistance of treated cotton (Wu and Yang 2008). Since wood cellulose has a lower crystallinity than cotton cellulose, and a higher content of accessible wood constituents such as lignin and hemicellulose, a similar reaction may be expected in wood.
In this study, the possibility to establish a stable modification system of wood with MA via the formation of cross-links in maleated wood with SHP was investigated.
Keywords: wood modification, sodium hypophosphite (SHP), maleic anhydride (MA)
Authors
Injeong Kim
Olov Karlsson
Dennis Jones
Dick Sandberg
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