DEVELOPMENT OF A RECYCLED COMPRESSION MOULDING COMPOUND Adam W. Smith Doctor of Philosophy Department of Mechanical Engineering McGill University Montreal, Québec March 2021 A thesis submitted to McGill University in partial fulfillment of the requirements of the degree of Doctor of Philosophy © Adam W. Smith, 2021 For Tarah, Alistair and Kingsley I TABLE OF CONTENTS TABLE OF CONTENTS ....................................................................................................................... II ACKNOWLEDGEMENTS ................................................................................................................... VI CONTRIBUTIONS OF THE AUTHOR ................................................................................................VIII ABSTRACT ..................................................................................................................................... IX RÉSUMÉ ......................................................................................................................................... XI LIST OF TABLES ...........................................................................................................................XIII LIST OF FIGURES ........................................................................................................................... XV LIST OF SYMBOLS & ABBREVIATIONS ...................................................................................... XXIII 1 INTRODUCTION ................................................................................................................... 29 1.1 A Growing Industry ................................................................................................... 29 1.2 Uncured Prepreg Offcuts ........................................................................................... 30 1.3 Composites Recycling................................................................................................ 31 1.4 A Recycled Prepreg Moulding Compound ................................................................ 32 1.5 Problem Statement ..................................................................................................... 33 1.6 Outline ........................................................................................................................ 34 2 LITERATURE REVIEW ......................................................................................................... 35 2.1 Composites Recycling................................................................................................ 35 2.1.1 Mechanical Recycling .................................................................................... 36 2.1.2 Incineration ..................................................................................................... 37 2.1.3 Fibre Reclamation .......................................................................................... 37 2.1.4 Reforming of Thermoplastic Composites ...................................................... 40 2.1.5 Uncured Prepreg Recycling ............................................................................ 42 2.1.6 Commercial Efforts ........................................................................................ 43 2.2 Long Discontinuous Fibre Composites ...................................................................... 44 2.2.1 Definition........................................................................................................ 44 2.2.2 Flow-Compaction ........................................................................................... 46 2.2.3 Mechanical Performance ................................................................................ 48 2.3 Expansion of Knowledge ........................................................................................... 50 II 3 THESIS OBJECTIVES AND STRUCTURE ............................................................................... 52 3.1 Thesis Objectives ....................................................................................................... 52 3.2 Thesis Structure.......................................................................................................... 53 4 RESIN CHARACTERIZATION ............................................................................................... 54 4.1 Materials..................................................................................................................... 54 4.2 Resin Extraction ......................................................................................................... 55 4.3 Cure Kinetics.............................................................................................................. 57 4.3.1 Test Matrix ..................................................................................................... 57 4.3.2 Model Fitting .................................................................................................. 58 4.3.3 Goodness of Fit .............................................................................................. 62 4.3.4 Model Validation ............................................................................................ 63 4.4 Rheology .................................................................................................................... 67 4.4.1 Test Matrix ..................................................................................................... 67 4.4.2 Model Fitting .................................................................................................. 67 4.4.3 Goodness of Fit .............................................................................................. 70 4.4.4 Model Validation ............................................................................................ 71 4.5 Glass Transition Temperature .................................................................................... 72 4.5.1 Test Matrix ..................................................................................................... 72 4.5.2 Model Fitting .................................................................................................. 72 5 ONE-DIMENSIONAL PREPREG FLOW-COMPACTION ......................................................... 75 5.1 Flow-Compaction Mechanisms ................................................................................. 75 5.2 Processing-Related Defects ........................................................................................ 76 5.3 Flow-Compaction Method ......................................................................................... 77 5.3.1 Specimen Design ............................................................................................ 77 5.3.2 Apparatus........................................................................................................ 78 5.3.3 Experiment Workflow .................................................................................... 79 5.4 Effect of Resin Viscosity ........................................................................................... 84 5.4.1 Temperature Reduction Trials ........................................................................ 84 5.4.2 Prepreg Staging .............................................................................................. 86 5.4.3 Test Matrix ..................................................................................................... 89 5.4.4 Results ............................................................................................................ 91 5.5 Effect of Mould Closure Rate .................................................................................... 97 5.5.1 Test Matrix ..................................................................................................... 97 5.5.2 Results ............................................................................................................ 98 5.6 Compression Moulding Process Map ...................................................................... 102 III 6 PREPREG AGEING ............................................................................................................. 104 6.1 Offcut Variability & Staging.................................................................................... 104 6.2 Methodology ............................................................................................................ 105 6.2.1 Offcut Ageing ............................................................................................... 105 6.2.2 DSC .............................................................................................................. 106 6.2.3 FT-IR ............................................................................................................ 106 6.2.4 GPC .............................................................................................................. 110 6.2.5 Tack .............................................................................................................. 112 6.3 Results ...................................................................................................................... 115 6.3.1 DSC .............................................................................................................. 115 6.3.2 FT-IR ............................................................................................................ 116 6.3.3 GPC .............................................................................................................