Wood effects

Nakano, T., Honma, S., Ehata, S. and Matsumoto, A. (1990b). Introduction of metals to chemically-modified woods. Effects of conformation and location of side chain on bonding. Mokuzai Gakkaishi, 36(8), 644-650. 

Chemical Changes in Wood Effected by Furnish Prepara-tion Processes... 

Ancm, C., Garde, T., Torrea, D., Jimenez, N. (2004). Extraction of volatile compounds in model wine from different oak woods. Effect of SO2. Food Res. Int., 37, 375-383. 

United States was used for this purpose. The most common compound used for this purpose was chromated copper arsenate (CCA). Wood preserved with CCA is referred to as pressure-treated wood. Wood treated with CCA is now recognized as a health hazard. Many authorities believe that humans and other animals exposed to pressure-treated wood may develop health problems because of arsenic present in the wood. For this reason, the U.S. Environmental Protection Agency (EPA) issued a ban on the use of CCA for treating wood, effective December 31, 2003. Pressure-treated wood may no longer be used for residential construction, although its use for industrial production is still permitted. 

Wood has characteristic properties of dimensional instability, flammability, and biodeterioration. Considering these properties as defects of wood, effective treatments by sol-gel process have been investigated to improve wood properties, without losing any favorable properties. The following discussion, therefore, deals with the effective property enhancement of wood by inorganic treatments and its topochemistry. 

Mayer J E and Wood W W 1965 Interfacial tension effects in finite periodic two-dimensional systems J. Chem. Phys. 42 4268-74... 

Effects on Visible Smoke. Smoke is a main impediment to egress from a burning building. Although some examples are known where specific phosphoms flame retardants increased smoke in small-scale tests, other instances are reported where the presence of the retardant reduced smoke. The effect appears to be a complex function of burning conditions and of other ingredients in the formulation (153,156,157). In a carehil Japanese study, ammonium phosphate raised or lowered the smoke from wood depending on pyrolysis temperature (158). Where the phosphoms flame retardant functions by char enhancement, lower smoke levels are likely to be observed. 

Extraction of hemiceUulose is a complex process that alters or degrades hemiceUulose in some manner (11,138). Alkaline reagents that break hydrogen bonds are the most effective solvents but they de-estetify and initiate -elimination reactions. Polar solvents such as DMSO and dimethylformamide are more specific and are used to extract partiaUy acetylated polymers from milled wood or holoceUulose (11,139). Solvent mixtures of increasing solvent power are employed in a sequential manner (138) and advantage is taken of the different behavior of various alkaUes and alkaline complexes under different experimental conditions of extraction, concentration, and temperature (4,140). Some sequences for these elaborate extraction schemes have been summarized (138,139) and an experimenter should optimize them for the material involved and the desired end product (102). 

Additives. Because of their versatility, imparted via chemical modification, the appHcations of ethyleneimine encompass the entire additive sector. The addition of PEI to PVC plastisols increases the adhesion of the coatings by selective adsorption at the substrate surface (410). PEI derivatives are also used as adhesion promoters in paper coating (411). The adducts formed from fatty alcohol epoxides and PEI are used as dispersants and emulsifiers (412). They are able to control the viscosity of dispersions, and thus faciHtate transport in pipe systems (413). Eatty acid derivatives of PEI are even able to control the viscosity of pigment dispersions (414). The high nitrogen content of PEIs has a flame-retardant effect. This property is used, in combination with phosphoms compounds, for providing wood panels (415), ceUulose (416), or polymer blends (417,418) with a flame-retardant finish. 

Table 13 shows some of the developmental products that have EPA appHcations pending and may be available in the near future. Sea Nine is a variation on the very successflil isothiazolone chemistry. It is claimed to be an improvement over metallic actives used for antifouling paint and wood preservation (46,47). Decylthioethylamine and its water-soluble hydrochloride are claimed to be especially effective at controlling biofilm in cooling water appHcations (48—50). The hydroxymethylpyra2ole shown is also suggested to have properties that are well suited to the protection of aqueous products or emulsions (51,52). 

Caro s acid is effective ia delignifying wood pulp (qv) made by chlorine-free bleaching sequences. When conditions are carefully controlled, the mechanical properties of the final paper (qv) are not impaired. These processes were developed ia the 1980s and commercialized ia the 1990s (68). 

The molecular weight of lignin in the wood, ie, of protolignin, is unknown. In addition to difficulties of isolation and purification, the polymer exhibits strong solvent, ionic, and associative effects in solution. An unequivocal method of measurement has not been developed. The polymer properties of lignin and its derivatives have been discussed (10,16). 

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