Thermophysical Properties of FRP Composites

Experimental investigations have shown that the thermal conductivity remains almost constant [8] or increases from the ambient temperature to resin decomposition [9, 10]. Consequently, similar to the specific heat capacity, the thermal conductivity before decomposition has been modeled as a constant value [7, 11] 

HigH Temperature Performance of Polymer Compels, First Edition. Yu Bai and Thomas Keller. 

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In this book, it is intended to provide the reader with useful and comprehensive experimental data and models for the design and application of FRP composites at elevated temperatures and fire conditions. The progressive changes that occur in material states and the corresponding progressive changes in the thermophysical and thermomechanical properties of FRP composites due to thermal exposure will be discussed. It will be demonstrated how thermophysical and thermomechanical properties can be incorporated into heat transfer theory and structural theory. The thermal and mechanical responses of FRP composites and structures subjected to hours of reahstic fire conditions will be described and validated on the full-scale structural level. Concepts and methods to determine the time-to-failure of polymer composites and structures in fire will be presented, as well as the post-fire behavior and fire protection techniques. 

This concept is applied in Chapters 4 and 5 that describe the temperature-dependent thermophysical and mechanical properties of FRP composite materials subjected to elevated temperature and fire. In Chapter 3, however, the estimation of the effective properties of a material mixture through a distribution function of its individual components (in different material states) is introduced first. 

FRP composites under elevated temperature and fire mostly correspond to a mixture of two material states, because - although three material states can be found in the full temperature range - only two states exist at a certain time. The thermophysical and mechanical properties of FRP composites under elevated temperature and fire estimated by the rule and inverse rule of mixture will be presented in Chapters 4 and 5 respectively. 

When exposed to high temperatures and fire, FRP composites experience complex changes in material states involving the interaction of thermal, chemical, physical, mechanical, and structural phenomena. Modeling and predicting aU the coupled responses of FRP stmctures is therefore a complex task. By treating independently only one or two of these phenomena in each model, however, the task becomes more reasonable. The thermal phenomena (heat transfer, temperature distribution, etc.) are mainly determined by the thermophysical properties of the material and the thermal boundary conditions, while the mechanical and stmctural phenomena... 

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