Microscopical analysis of formaldehyde-acid modified wood
M Stevens, N Parameswaran
Cross-linking of wood with gaseous formaldehyde improves its hygroscopic and dimensional behaviour, and its resistance against micro-organisms. However, formaldehyde cross-linking reactions take place only in the presence of an acid catalyst, which results in losses in mechanical By optimization of a formaldehyde-sulfur dioxide vapour phase process the reaction conditions were established to limit losses in modulus of elasticity and bending strength to a few percent. Under these circumstances, impact strength losses of about 50 to 75% were still noted. The reaction of formaldehyde with cellulose has been studied intensively in textile research. However little is known on the fundamental aspects of the interaction of formaldehyde with lignin and wood. In order to get further insight into the effects of a formaldehyde-acid catalyzed reaction on the technological properties of wood a fundamental analysis of the interactions of both compounds with wood has been carried out.