Wood, wetting

Phase C corresponds to a decreasing rate of temperature rise in the board core at about 100°C. It is followed by stabilization of the temperature, namely phase D. This latter being due to decrease of the steam gradient due to moisture escape from the board edges, and the increase and decrease of the wood wetting heat, respectively, near the board surface and in the core layer. Phase E, a new slow increase in temperature is observable in standard moisture content boards [225] but is absent at high moisture content (due to the maintenance of some moisture in the core layer), contrary to the case of traditional moisture content adhesives, as shown in Fig. 8. 

The term gasification as used here refers to the reaction of wood (wet) with air to yield a low heating value gas. The major components of the fuel gas produced are formed by various reactions between carbon and water in the fuel with oxygen in the air. 

Figure 13 Shapes of CDCB phenolic FRP-wood specimens, (a) Geometry of phenolic FRP-wood/ dry specimen (b) geometry of phenolic FRP-wood/wet specimen.

Features Self-cnosslinking scuff and mar resistance high gloss and clarity fast dry time exc. wood wetting superior durability Regubt DOT nonregulated SARA 313 reportable Canada DSL listed Properties Lt. tan to amber translucent liq. mild amine odor misc. with water dens. 8.85 Ib/gal vise. 250 cps b.p. 89 C flash pt. (PMCC) > 93 C pH 8 31% solids... 

WOOD. Wet wood has caused varying degrees of corrosion of contacting aluminum aJIoys in labora-tmy tests. The degree of corrosion varied with the type of wood tested. It is good engineering practice to apply protection where aluminum alloys will contact wood which may become wet. Aluminum alloy nails, screws, and bolts have been used in wood. See also Ref (Dp. 147, (3) p. 231. 

Given the mechanisms and temperatures, waste combustion systems typically employ higher percentages of excess air, and typically also have lower cross-sectional and volumetric heat release rates than those associated with fossil fuels. Representative combustion conditions are shown in Table 11 for wet wood waste with 50—60% moisture total basis, municipal soHd waste, and RDF. 

Nonwood fibers are used in relatively small volumes. Examples of nonwood pulps and products include cotton Enters for writing paper and filters, bagasse for cormgated media, esparto for filter paper, or Manila hemp for tea bags. Synthetic pulps which are based on such materials as glass (qv) and polyolefins also are used (see Olefin polymers). These pulps are relatively expensive and usually are used in blends with wood pulps where they contribute a property such as tear resistance, stiffness, or wet strength which is needed to meet a specific product requirement. 

Fiberboard or hardboard is made of low grade wood and wood waste. In the wet production process, a sheet is produced on a papermaking machine, such as a fourdrinier. A Hquid resole is usually added to the beater section and precipitated onto the wood fibers by adjusting the pH. The moderately dry felt is further dried and cured in an off-line press. 

Closed-Mill Concept. The closed-mill concept, or water circuit closure, has been studied by the pulp and paper industry for many years. In some parts of the paper manufacturing process, up to 98% of the water is recycled within the process, eg, the wet end of the paper machine. However, in the pulp mill, especiaUy kraft mills, effluents are produced owing to the need to purge from the system various metals that come in with the wood, as weU as organic by-products from the pulping process, additives, and especially chloride ions that originate in the bleach plant. 

Bacterial degradation of wood generally is not a serious problem, although in some situations of extreme wetness, bacteria may increase the permeabihty of wood after many years or reduce the strength of the wood (58). 

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