Thermophysical decomposition heat

The thermal response of a material is largely influenced by the pyrolysis gases and decomposition heat One way to consider these effects is to introduce them into the final governing equations of the thermal response model another possibility is to consider these effects in the effective thermophysical properties. 

Much information can be understood by a review of certain thermophysical properties of materials and mixtures. In comparing the values of heats of reaction, heats of decomposition and CART to values for known hazardous compounds, an estimation of thermal hazard potential can be made. Table A.2 outlines thermal hazard ranking values that could be used in classifying materials and processes based on heats of reaction and CART determinations (Melhem and Shanley 1997). 

As described in the previous sections, the changes in the effective thermophysical properties (density, thermal conductivity, and specific heat capacity) are mainly determined by the decomposition process. This process, being kinetic, is not just an univariate function of temperature, but also on time. Therefore, and in contrast to true material properties, effective properties are dependent not only on temperature, but also on time. In order to model the time-dependent physical properties, related kinetic processes must be taken into account, as described by the kinetic equations in Chapter 2. 

A one-dimensional thermal response model was developed to predict the temperature of FRP structural members subjected to fire. Complex boundary conditions can be considered in this model, including prescribed temperature or heat flow, as well as heat convection and/or radiation. The progressive changes of thermophysical properties including decomposition degree, density, thermal conductivity, and specific heat capacity can be obtained in space and time domains using this model. Complex processes such as endothermic decomposition, mass loss, and delatnina-tion effects can be described on the basis of an effective material properties over the whole fire duration. 

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