Wood thermal conductivity Table

In this research, thermal insulation properties of the wood sawdust/PC composites were evaluated by thermal conductivity analysis. Table 1 shows the thermal conductivity of sawdust/PC composites in various treatments. Thermal conductivity is defined as the quantity of heat transmitted through a unit thickness in a direction normal to the surface of that unit area, due to a unit temperature gradient under steady state conditions [6]. The addition of wood can improve thermal insulation of neat PC because thermal conductivity (k) of wood materials (k 0.08 W/m K [9] was normally lower than plastics. Moreover, the lower thermal conductivity was associated with discontinuous phases which were a result from poor compatibility between the wood sawdust and PC matrix [7]. 

Fillers are relatively nonadhesive substances added to the adhesive formulation to improve its working properties, strength, permanence, or other qualities. The improvements resulting from the use of fillers are listed in Table 1.8. Fillers are also used to reduce material cost. By selective use of fillers, the properties of an adhesive can be changed significantly. Thermal expansion, electrical and thermal conduction, shrinkage, viscosity, and thermal resistance are only a few properties that can be modified by the use of fillers. Common fillers are wood flour, silica, alumina, titanium oxide, metal powders, china clay and earth, slate dust, and glass fibers. Some fillers may act as extenders. 

The fuels were pellets and wood cylinders (pine). The pellets were made of compressed sawdust and had a diameter of 8 mm. The wood cylinders had three diameters, 8, 12 and 34 mm. The proximate analyses and elemental composition of the fuels were almost identical, as seen in Table 1. The density and the thermal conductivity of the pellets are about twice those of the wood. The pellets were burned both in the large and in the small rig, while the wood cylinders were burned only in the small one. 

The cause of this difference could be a possible combined effect of the thermal conductance and the gas permeability. The thermal conductance is the lowest for blocks 16 poplar (see table I) and the permeability to gases is the lowest for poplar. These two factors combined could contribute to delay and slow down the production of volatile matter for blocks 16 of poplar. However, we must stress the fact that the difference between these blocks 16 poplar and the other samples is not that big, although significant in the case of factor a, the difference is S to 6 min for anhydrous wood samples, 20 to 30 min for wet wood samples, when moisture content generates differences between anhydrous and wet samples of the order of 60 min. 

The relative insulation characteristics of polyurethane foam and polystyrene foam as compared to brick and wood is given in Fig. 3.3. Thermal conductivity coefficients, thermal expansion coefficients and dielectric constants for various polymers and other materials are given in Table 3.3. 

Table 1. Thermal conductivity values for wood sawdust/PC composites at wood content 10 %wt...

The thermal conductivity of neat PC, wood sawdust and composites retrieved from equation (1) would represent theoretical value where those numbers from experiment were shown in Table 2. The experimental thermal conductivity were lower than theory one. It might be cause of void occur in the matrix. 

A time to reach blister temperature for paint removal was used to determine the relative speed of paint removal. In each case, the paint consisted of an alkyd resin binder on painted metal and wood surfaces. A calibrated thermocouple attached to a unit with a digital temperature scale was placed directly on the surface, and the temperature was recorded when the paint blistered Table 11.12 lists the results. This test showed that a metal substrate requires more cleaning time (+5-72 sec) and a higher temperature (+77-82 °F (+22-28 °C)) than less thermally conductive substrate, such as wood. 

We often describe physical objects as being warm, cool, cold, hot, etc. What is interesting is that we may describe different objects that are at the same temperature as feeling different. This is due to the amount of heat, the thermal energy, that is transferred between those objects and our skin. The amount of heat transferred is dependent on the total amount of contact (the surface area) and the thermal conductivity coefficient (TCC) of the object. An object that has high TCC, such as most metals, will transfer heat much faster than an object with a low TCC, such as wood or thermoplastic. Below is a table with TCC values for a number of common materials (Table 7.2). 

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