High Temperature Performance of Polymer Composites

The authors explain the changes in the thermophysical and thermomechanical properties of polymer composites under elevated temperatures and fire conditions. Using microscale physical and chemical concepts they allow researchers to find reliable solutions to their engineering needs on the macroscale. In a unique combination of experimental results and quantitative models, a framework is developed to realistically predict the behavior of a variety of polymer composite materials over a wide range of thermal and mechanical loads. In addition, the authors treat extreme fire scenarios up to more than 1000?C for two hours, presenting heat–protection methods to improve the fire resistance of composite materials and full–scale structural members, and discuss their performance after fire exposure. Thanks to the microscopic approach, the developed models are valid for a variety of polymer composites and structural members, making this work applicable to a wide audience, including materials scientists, polymer chemists, engineering scientists in industry, civil engineers, mechanical engineers, and those working in the industry of civil infrastructure.

Preface XI 1 Introduction 1 1.1 Background 1 1.2 FRP Materials and Processing 4 1.2.1 FRP Materials 4 1.2.2 Processing Technologies 6 1.3 FRP Structures 7 1.3.1 Pontresina Bridge 7 1.3.2 Eyecatcher Building 9 1.3.3 Novartis Main Gate Building 11 1.4 Structural Fire Safety 15 1.4.1 Possible Fire Threats 15 1.4.2 Building Fire Standards 16 1.5 Summary 19 References 19 2 Material States of FRP Composites under Elevated and High Temperatures 21 2.1 Introduction 21 2.2 Glass Transition 24 2.2.1 Characterization 24 2.2.2 Glass–Transition Temperature 26 2.2.3 Frequency Dependence of Glass–Transition Temperature 27 2.2.4 Heating Rate Dependence of Glass–Transition Temperature 29 2.2.5 Modeling of Glass Transition 31 2.3 Leathery–to–Rubbery Transition 32 2.4 Decomposition 33 2.4.1 Characterization 33 2.4.2 Decomposition Temperature 34 2.4.3 Modeling of Decomposition 34 2.5 Summary 35 References 36 3 Effective Properties of Material Mixtures 39 3.1 Introduction 39 3.2 Volume Fraction of Material State 40 3.2.1 General Case – n Elementary Processes 40 3.2.2 Two Processes – Glass Transition and Decomposition 40 3.3 Statistical Distribution Functions 42 3.3.1 In Cases of Two Material States 43 3.3.2 In Cases of Three Material States 44 3.4 Estimated Effective Properties 44 3.5 Summary 44 References 45 4 Thermophysical Properties of FRP Composites 47 4.1 Introduction 47 4.2 Change of Mass 48 4.2.1 Decomposition Model 48 4.2.2 TGA 48 4.2.3 Estimation of Kinetic Parameters 49 4.2.3.1 Friedman Method 50 4.2.3.2 Kissinger Method 51 4.2.3.3 Ozawa Method 52 4.2.3.4 Comparison 54 4.2.4 Mass Loss 55 4.3 Thermal Conductivity 57 4.3.1 Formulation of Basic Equations 57 4.3.2 Estimation of kb and ka 58 4.3.3 Comparison to Other Models 59 4.4 Specific Heat Capacity 62 4.4.1 Formulation of Basic Equations 62 4.4.2 Estimation of Cp,b and Cp,a 62 4.4.3 Decomposition Heat, Cd 64 4.4.4 Moisture Evaporation 65 4.4.5 Comparison of Modeling and Experimental Results 65 4.5 Time Dependence of Thermophysical Properties 70 4.5.1 Introduction 70 4.5.2 Influence of Heating Rates on Decomposition and Mass Transfer 71 4.5.3 Influence on Effective Specific Heat Capacity 73 4.5.4 Influence on Effective Thermal Conductivity 75 4.6 Summary 76 References 77 5 Thermomechanical Properties of FRP Composites 79 5.1 Introduction 79 5.2 Elastic and Shear Modulus 80 5.2.1 Overview of Existing Models 80 5.2.2 Estimation of Kinetic Parameters 81 5.2.3 Modeling of E–Modulus 85 5.2.4 Modeling of G–Modulus 86 5.3 Effective Coefficient of Thermal Expansion 86 5.4 Strength 87 5.4.1 Shear Strength 88 5.4.2 Tensile Strength 90 5.4.3 Compressive Strength 93 5.5 Summary 96 References 98 6 Thermal Responses of FRP Composites 99 6.1 Introduction 99 6.2 Full–Scale Cellular Beam Experiments 100 6.2.1 Material Details 100 6.2.2 Specimen and Instrumentation 100 6.2.3 Experimental Setup and Procedure 101 6.2.4 Experimental Observation 104 6.2.5 Thermal Response from Measurements 105 6.2.6 Discussion 108 6.3 Thermal Response Modeling of Beam Experiments 109 6.3.1 Modeling Assumptions and Simplification 109 6.3.2 Thermal Responses Modeling 111 6.3.3 Results and Discussion (Noncooled Specimen SLC03) 114 6.3.4 Results and Discussion (Liquid–Cooled Specimen SLC02) 119 6.4 Full–Scale Cellular Column Experiments 123 6.4.1 Material and Specimens 123 6.4.2 Experimental Scenarios and Setup 123 6.4.3 Instrumentation 125 6.4.4 Experimental Observation 126 6.4.5 Thermal Responses from Measurements 127 6.5 Thermal Response Modeling of Column Experiments 130 6.6 Summary 130 References 131 7 Mechanical Responses of FRP Composites 133 7.1 Introduction 133 7.2 Full–Scale Cellular Beam Experiments 134 7.3 Mechanical Response Modeling of Beam Experiments 137 7.3.1 Modeling of Thermal Responses 137 7.3.2 Modeling of Mechanical Properties 137 7.3.3 Modeling of Elastic Responses 137 7.3.4 Model Extension: Effects of Thermal Expansion 140 7.3.5 Discussion of Deformation Modeling 142 7.3.6 Failure Analysis 142 7.4 Full–Scale Cellular Column Experiments 143 7.5 Mechanical Response Modeling of Column Experiments 145 7.5.1 Modeling of Modulus Degradation 145 7.5.2 Modeling of Time–Dependent Euler Buckling Load 145 7.5.3 Modeling of Time–Dependent Lateral Deformation 147 7.5.4 Time–to–Failure Prediction and Damage Location 150 7.6 Axial Compression Experiments on Compact Specimens 152 7.6.1 Materials and Specimens 152 7.6.2 Thermal Response Experiments 152 7.6.3 Structural Endurance Experiments 154 7.6.4 Results of Thermal Response Experiments 155 7.6.5 Results of Structural Endurance Experiments (MN1 and MN2) 157 7.6.6 Results of Structural Endurance Experiments (MC1 and MC2) 157 7.6.7 Results of Structural Endurance Experiments (MC3 and MC4) 158 7.7 Modeling of Compression Experiments on Compact Specimens 159 7.7.1 Temperature Responses 159 7.7.2 Strength Degradation 160 7.7.3 Time–to–Failure 164 7.8 Axial Compression Experiments on Slender Specimens 165 7.8.1 Materials and Specimens 166 7.8.2 Dynamic Mechanical Analysis 166 7.8.3 Axial Compression Experiments 166 7.8.4 DMA Results 167 7.8.5 Temperature Response Results 168 7.8.6 Load–Displacement Responses 168 7.8.7 Buckling Load 170 7.8.8 Temperature–Dependent Compressive and Bending Stiffness 171 7.8.9 Failure Modes 172 7.9 Modeling of Compression Experiments on Slender Specimens 174 7.9.1 Temperature–Dependent E–Modulus 174 7.9.2 Temperature–Dependent Buckling Load 174 7.9.3 Temperature–Dependent Nondimensional Slenderness 175 7.9.4 Post–Buckling Delamination Analysis 176 7.9.5 Kink–Band Analysis 178 7.10 Summary 179 References 181 8 Post–Fire Behavior of FRP Composites 183 8.1 Introduction 183 8.2 Post–Fire Behavior of FRP Beams 184 8.2.1 Pre–Fire, Fire Exposure, and Post–Fire Load–Deflection Responses 185 8.2.2 Pre–Fire, Fire Exposure, and Post–Fire Stiffness 185 8.2.3 E–Modulus Recovery Quantified by DMA Tests 186 8.3 Post–Fire Modeling of FRP Beams 187 8.3.1 Temperature Gradient–Based Modeling 187 8.3.2 RRC–Based Model 187 8.3.3 Proposed Model Considering Modulus Recovery 188 8.3.4 Comparison 192 8.4 Post–Fire Behavior of FRP Columns 194 8.4.1 Experimental Investigation 194 8.4.2 Experimental Results 196 8.5 Post–Fire Modeling of FRP Columns 200 8.5.1 Post–Fire Stiffness 200 8.5.2 Post–Fire Euler Buckling Load 202 8.5.3 Second–Order Deformation 204 8.5.4 Post–Fire Ultimate Load 205 8.6 Comparison to Post–Fire Beam Experiments 208 8.7 Summary 209 References 210 9 Fire Protection Practices for FRP Components 211 9.1 Introduction 211 9.2 Passive Fire Protection 211 9.2.1 Fire Retardants 212 9.2.2 Nanocomposites 213 9.2.3 Inherently Fire Retardant Resins (Phenolic Resins) 213 9.2.4 Intumescent Coatings and Other Surface Protections 214 9.3 Active Fire Protection 215 9.3.1 Sprinkler Systems 215 9.3.2 Internal Liquid Cooling 215 9.4 Passive Fire Protection Applications with FRP Components 216 9.4.1 Calcium Silicate Board 216 9.4.2 Cementitious Mortar 218 9.4.3 Intumescent Coating 220 9.4.4 Fire Resistant Gypsum Plasterboard 222 9.5 Active Fire Protection Applications with FRP Components 225 9.6 Summary 227 References 227 Index 229

Yu Bai received his PhD in civil engineering from the Ecole Polytechnique Fédérale de Lausanne (EPFL) Switzerland in 2009 and became an academic in the Department of Civil Engineering of Monash University Australia in the same year. His research investigates the material and structural responses of fiber–reinforced polymer composites under critical load and environmental conditions such as fire, combined temperature and humidity, and sea water exposure. His research efforts are also focused on developing new building techniques and structural systems using fiber–reinforced polymer composite materials. In 2012, he received the Discovery Early Career Researcher Award from the Australia Research Council, as the inaugural recipient. Thomas Keller obtained his civil engineering degree and his doctoral degree from the Swiss Federal Institute of Technology (ETH) Zurich. In 2007, he was appointed Full Professor of Structures at the School of Architecture, Civil and Environmental Engineering at the Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland. In addition, Thomas Keller is founder and director of the Composite Construction Laboratory (CCLab). His research work is focused on polymer composites and hybrid materials and engineering structures with an emphasis on lightweight multifunctional structures.