Polyethylene glycol, wood stabilization

Grelier etal. (1997) synthesized a variety of UV stabilizers based upon hydroxy-phenylbenzotriazoles incorporating an isocyanate functionality. These were reacted with wood using microwave energy. The modified woods were exposed to UV irradiation and the photoinduced discolouration determined. It was found that the best protection was obtained when the UV stabilizer was used in conjunction with polyethylene glycol, or hindered amine light stabilizers. 

The strength properties of polyethylene glycol treated wood are virtually those of the swollen wood. This is not surprising as the polymer tends to maintain green wood dimensions. Unlike heat stabilized and formaldehyde cross-linked wood and wood bulked by resin forming polymers within the cell walls (to be considered later), the toughness of the wood is not adversely affected by polyethylene glycol treatment (35). 

Recent experiments to determine the dimension stabilizing efficiency of water soluble fire retardent chemicals (41) showed ammonium sulfamate to be superior to phosphate salts, giving anti shrink efficiencies of 51 to 66% compared to polyethylene glycol-1000 values of 63 to 77%. Sodium silicate, because of its alkalinity, caused collapse of the wood that resulted in negative anti shrink efficiencies. Strongly alkaline systems should hence be avoided. 

Bulking Treatment with Water Insoluble Chemicals. The chief shortcomings of dimensional stabilization of wood with polyethylene glycol are that it can be leached from the wood and that the wood feels damp when held for prolonged periods of time at relative humidities of 80% and above. It thus appears desirable to deposit water insoluble materials within the cell walls of wood. This can be done by a replacement process with waxes (42). Water in green wood is replaced by Cellosolve (ethylene glycol monoethyl ether) by soaking the wood in this... 

Treatment of wood with polyethylene glycol (PEG) is the most commonly used method to impart dimensional stability to wood. PEG in a water solution can be used to permeate the lumens and penetrate the cell wall. A 30-50 percent solution of PEG in water generally is used on green wood no pressure is required. Treatment times are adjusted so that a uniform uptake of 25-30 percent of PEG is achieved, based on the dry weight of the wood temperatures range from 21 to 60°C. The wood may require weeks of soaking, depending on species, density, and thickness. After treatment, the wood is dried in a well-ventilated space, preferably heated. 

Treatment of solid wood over the years for increased utility included many chemical systems that affected the cell wall and filled the void spaces in the wood. Some of these treatments found commercial applications, while some remain laboratory curiosities. A brief description of the earlier treatments is given for heat-stabilized wood, phenol-formaldehyde-treated veneers, bulking of the cell wall with polyethylene glycol, ozone gas-phase treatment, ammonia liquid- and gas-phase treatment, and p- and y-radiation. Many of these treatments led to commercial products, such as Staybwood, Staypak, Im-preg, and Compreg. This chapter is concerned primarily with wood-polymer composites using vinyl monomers. Generally, wood-polymers imply bulk polymerization of a vinyl-type monomer in the void spaces of solid wood. 

Mi YI, Wood J. The application and mechanisms of polyethylene glycol 8000 on stabilizing lactate dehydrogenase during lyophilization. PDA ] Pharm Sci Technol 2004 58(4) 192-202. 

Alfred Stamm studied swelling of fibers at the Forest Products Research Laboratory in Madison, Wisconsin, during the 1940s. In 1956 Stamm published a paper (i) about dimension stabilization of wood with polyethylene glycol. The object of the research was discovery of a way to season green wood. The use of PEG for such seasoning was soon introduced on an industrial scale in the United States. 

As an alternative to the conventional polyethylene glycol (PEG) treatment of waterlogged wood see Chapter 8), attempts were made in 1966-1967 to apply a radiation-curing process (i, 2). The aim was to reduce treatment time and achieve more stability for treated objects subjected to interior climatic changes. The impregnation of waterlogged wood by immersion involves a liquid-liquid exchange process. Dry wood was directly bulked by monomers by a vacuum-pressure process. 

Dimensionally Stabilized Wood. Wood that has been saturated by immersion in water for long periods of time and subjected to related biological deterioration will often require a dimensional stabilization treatment before drying can be permitted safely. This treatment is usually done with bulking compounds such as polyethylene glycol (PEG). 

Dimensional stability treatment Reduces or prevents swelling in the fibers Bulking the cell wall with polyethylene glycol, penetrating polymers, or bonded cell wall chemicals, or crosslinking cell wall polymers. Mostly used in wood fibers. 

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