Analysis of Fire Performance, Smoke Development and Combustion Gases from Flame Retarded Rigid Polyurethane Foams by David Olabode Adeosun A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Doctor of Philosophy in Mechanical Engineering Waterloo, Ontario, Canada, 2014 © David Olabode Adeosun 2014 Author’s Declaration I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Abstract Rigid polyurethane foam is a polymeric material which is widely used for thermal insulation in building construction and other applications. Given recent emphasis on energy conservation and efficiency, there has been continuous growth in its use over the years. This raises significant fire safety concerns since polyurethanes are inherently very flammable and prone to release toxic gases as the foam thermally decomposes and burns. To improve fire safety characteristics by reducing ignitability and flammability of the foams, various flame retardants (FR) have been introduced into base foam formulations. But with the introduction of FR agents, there has been rising concern within the fire safety community and general public regarding the overall benefits versus detrimental impacts of even commonly used FR agents. In the case of rigid polyurethane foam, however, such an assessment is difficult as there are few cross comparisons in the literature that detail the impacts of different concentrations of common fire retardants, such as brominated, phosphorus-based and expandable graphite agents, on the fire behavior, smoke development and toxic gas production for even single base foam formulations. The present experimental work focuses on a systematic evaluation of these factors using three common, commercial fire retardants added in concentrations of 0%wt, 10%wt and 20%wt to a single formulation of rigid polyurethane foam. Cone calorimeter and smoke density tests are used to simulate well ventilated and poorly ventilated fire conditions during material fire performance assessment, while FTIR, Novatech P 695 gas analyzers and TD-GC/MS methods are used to investigate the gases evolved during oxidative pyrolysis and combustion of the samples. Concentration measurements of principal fire gases such as CO, CO2, reduced O2, and NOx iii are combined with more detailed investigation of the volatile organic compounds generated during the fire testing. Use of gas absorption sampling followed by off-line Thermal Desorption/Gas Chromatography/Mass Spectrometry (TD-GC-MS) analysis for identification of toxic gases has proven of significant benefit in this application. The full set of data obtained provides a more comprehensive identification of the evolved products during three characteristic periods in the combustion process. As such, it expands current knowledge and provides valuable new insight and understanding of thermal degradation, combustion and smoke development, as well as overall fire performance, of fire retarded rigid polyurethane foams in well-ventilated and poorly ventilated environments. iv Acknowledgements I would like to thank several people without whom this work would not have been possible. My profound gratitude goes to my supervisor, Professor Elizabeth Weckman, for her mentorship, support, technical guidance and insightful comments over the years. Thank you for being patient with me during my learning curves. I would also like to thank Professors William Epling, David Torvi and Tadeusz Gorecki who offered valuable advice during our discussion meetings. My thanks also go to all members of the Examining Committee for their advice and suggestions in the course of this study. My special thanks to Gord Hitchman, the Research Specialist at the UW Fire Labs, who provided valuable help and expertise in the experimental design and lab work; his presence in the lab throughout most of this work, was of great help. Thank you Gord. I would also like to thank Mr Andy Barber for his technical assistance in troubleshooting the electronics in the Novatech Gas Analyzer systems. I also express my gratitude to Woodbridge Foam Corporation for supplying the foam samples used in this study and thanks to Mr. Herbert Schmidt for creating time out of his tight work schedule for the production of the samples we used over the course of this study. I would also like to acknowledge my colleagues at the University of Waterloo Fire Research Group for their support and encouragement throughout my study period. I particularly appreciate Ms Janet Rigg and Mr. Matt DiDomizio for their contributions towards this work. I am also grateful to Faten Salim and Mathew Edwards at the Analytical Chemistry Lab for their co-operation and support in the use of GC/MS equipment. v Finally, I acknowledge the help and faithfulness of God in the pursuit of this study. I owe it all to Him. And to my wife and family who have always spurred and encouraged me into excellence in life and ministry. Thank you all for being there. vi Table of Contents AUTHOR’S DECLARATION ...................................................................................................... II ABSTRACT ............................................................................................................................ III ACKNOWLEDGEMENTS .......................................................................................................... V TABLE OF CONTENTS ........................................................................................................... VII LIST OF FIGURES .................................................................................................................... X LIST OF TABLES .................................................................................................................... XII NOMENCLATURE ................................................................................................................ XIII ACRONYMS ......................................................................................................................... XV CHAPTER ONE: INTRODUCTION ............................................................................................. 1 1.1 POLYURETHANE FOAMS AND FIRES................................................................................................. 1 1.2 MOTIVATION ............................................................................................................................. 5 1.3 RESEARCH OBJECTIVES ................................................................................................................. 7 CHAPTER TWO: LITERATURE REVIEW ................................................................................... 10 2.1 POLYURETHANE FOAM PRODUCTION ............................................................................................ 10 2.2 FLAME RETARDANTS MECHANISMS IN RIGID POLYURETHANE FOAMS .................................................... 11 2.2.1 Brominated Flame Retardants ..................................................................................... 14 2.2.2 Phosphorus Flame Retardants ...................................................................................... 20 2.2.3 Intumescent Flame Retardants..................................................................................... 23 2.3 SUMMARY OF WORK TO DATE ON FLAME RETARDED RIGID POLYURETHANE FOAMS ................................. 25 2.4 STAGES OF FIRE DEVELOPMENT .................................................................................................. 28 2.4.1 Stage I: Thermo-oxidative pyrolysis .............................................................................. 31 2.4.2 Stage II: Fully Developed Fires ...................................................................................... 38 2.4.3 Stage III: Post Flashover Fires ....................................................................................... 40 2.5 FIRE PERFORMANCE CHARACTERISTICS .......................................................................................... 41 2.6 COMBUSTION PRODUCTS ........................................................................................................... 45 2.6.1 Smoke Products ............................................................................................................ 47 2.6.2 Principal Fire Gases ....................................................................................................... 50 2.6.2.1 Reduced Oxygen Concentration (O2) ..................................................................... 53 2.6.2.2 Carbon dioxide (CO2) ............................................................................................. 53 2.6.2.3 Carbon monoxide yield (CO) .................................................................................. 54 2.6.2.4 Smoke Toxicity Index (CO/CO2).............................................................................. 54 2.6.2.5 Nitrogen Oxides (NOx) ........................................................................................... 55 vii 2.6.2.6 Organic Compounds............................................................................................... 56 2.7 GAS GENERATION METHODS ...................................................................................................... 59 CHAPTER THREE: EXPERIMENTAL APPARATUS AND