Dimensional stability thermally modified wood

Spruce meal and beech blocks were modified by using a mixture of perfluoroalkyl ethanol and MDI. Improved dimensional stability and water repellency were reported (Engonga etal., 1999). In order to avoid the handling problems associated with the use of most isocyanates, the generation of isocyanates within the wood by thermal rearrangement of acyl azides has been studied (Gdrardin etal., 1995) (Figure 4.8). This is potentially a... 

Considerable efforts have been directed, during the last few years, to grafting various vinyl and acrylic monomers on cellulosic fibers or films in order to modify their properties in a predetermined way. It was shown that one can graft large amounts of vinyl-type monomers, such as acrylonitrile or acrylic esters on rayon, cotton, cellophane, paper, and wood, thus modifying the properties of the base material in many respects, and improving, particularly, dimensional stability, water repellency, and resistance to thermal and chemical degradation. 

The hydrophilic character of wood, intrinsically connected with the structure of its three main macromolecular components, has been a longstanding source of problems, mostly arising from its lack of dimensional stability in moist environments. An additional major drawback is its susceptibility to photolytic and biological degradation. The interest of both scientists and technologists in modifying wood in order to overcome these drawbacks has called upon specific treatments like chemical, thermal, enzymatic or purely physical modifications. This chapter examines recent contributions to these issues, based on approaches which only involve the chemical modification of wood, carried out in bulk or at its surface. The other treatments have been aptly covered in a recent book [1] and a thorough review [2]. 

R. Rashmi, A. Devi, T.K. Maji, and A.N. Banerjee, Studies on dimensional stability and thermal properties of rubber wood chemically modified with styrene and glycidyl methacrylate. /. Appl. Polym. Sc. 93,1938-1945 (2004). 

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