Specific absorption material properties

The FDS5 pyrolysis model is used here to qualitatively illustrate the complexity associated with material property estimation. Each condensed-phase species (i.e., virgin wood, char, ash, etc.) must be characterized in terms of its bulk density, thermal properties (thermal conductivity and specific heat capacity, both of which are usually temperature-dependent), emissivity, and in-depth radiation absorption coefficient. Similarly, each condensed-phase reaction must be quantified through specification of its kinetic triplet (preexponential factor, activation energy, reaction order), heat of reaction, and the reactant/product species. For a simple charring material with temperature-invariant thermal properties that degrades by a single-step first order reaction, this amounts to -11 parameters that must be specified (two kinetic parameters, one heat of reaction, two thermal conductivities, two specific heat capacities, two emissivities, and two in-depth radiation absorption coefficients). 

A wide variety of techniques have been employed for the characterization of thin film samples of nonlinear polymeric materials. Many of these are similar to techniques described in the previous section for bulk material characterization, and are employed with thin film samples both to assess differences in material properties in the two physical forms and because certain measurements such as absorption or electro-optic effects may be more easily made in thin film samples. Other techniques are specific to thin film samples in which light can be guided, for which parameters can be measured having no bulk equivalent, such as waveguide scatter or nonlinear mode coupling. 

Mixing of polymers is an important process in the polymer industry by combining the strength of different polymers through blending, new products with desirable physical properties can be produced [2]. FT-IR imaging with a micro-ATR objective has been used to study the effect of a compatibilizer on the mixing of two immiscible polymers, namely polystyrene (PS) and low-density polyethylene (LDPE). The compatibilizer used in this study is a triblock copolymer of polystyrene-f -poly(ethylene-butylene)-f)-polystyrene (SEES). The blends are prepared with a micro-extruder, which allows small amounts of the materials to be blended [2]. The two polymers are easily characterized by their specific absorption bands at 1492 and 1450 cm for PS and the band at 1466 cm for LDPE. 

Physical Properties. Physical properties include specific gravity, water absorption, mold shrinkage, transmittance, ha2e, and refractive index. Specific gravity affects performance and has commercial implications. The price of the material divided by the specific gravity gives the yield in cost per unit volume. Comparison of yields gives an evaluation of raw material costs. 

Carbon blacks are synthetic materials which essentially contain carbon as the main element. The structure of carbon black is similar to graphite (hexagonal rings of carbon forming large sheets), but its structure is tridimensional and less ordered. The layers of carbon blacks are parallel to each other but not arranged in order, usually forming concentric inner layers (turbostratic structure). Some typical properties are density 1.7-1.9 g/cm pH of water suspension 2-8 primary particle size 14-250 nm oil absorption 50-300 g/100 g specific surface area 7-560 m /g. 

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