Handbook of Polymeric Foams and Foam Technology

Transcription

1 Handbook of Polymeric Foams and Foam Technology 2nd Edition Edited by Daniel Klempner and Vahid Sendijarevic With contributions by R.M. Aseeva, K. Ashida, J.K. Backus, T. Baumann, R. Broos, L. Domeier, C.V. Gupta, J.R. Harper, R. Herrington, P.T. Kelly, D. Klempner, P. Knaub, R.F. Mausser, W. Nicholson, C.B. Park, C.P. Park, J.H. Saunders, V. Sendijarevic, F.A. Shutov, K.W. Suh, D. Visco, F. Xing HANSER Hanser Publishers, Munich Hanser Gardener Publications, Inc., Cincinnati

2 Contents Preface IX 1 Introduction References 4 2 Fundamentals of Foam Formation Introduction Fundamental Principles of Foam Formation Bubble Formation Bubble Growth Bubble Stability Supporting Evidence from Specific Foam Systems Thermoplastic Foams Polyurethane Foams Cellular Rubber Summary References 14 3 Cellular Structure and Properties of Foamed Polymers Introduction Porous and Cellular Systems Statistical Meaning of the Concept of a Cell Terminology Basic Relationships Packing Types Open- and Closed-Cell Foamed Plastics General Problems Open Cells and Density Reticulated Foams Density of Foamed Polymers Classification Density and Cell Size Density and Wall Thickness Cell Shape of Foamed Polymers Cell Shape Models and 14-Hedrons Anisotropy of Cell Shapes Cell Size of Foamed Polymers Methods of Estimation Cell Size and Number of Cells Cell Size and Wall Thickness Microcells Cell Size and Physical Properties Models of Cellular Structure and Calculation of Mechanical Properties of Foamed Polymers 38

3 XII Contents Flexible Foamed Polymers Rigid Foamed Polymers Cellular Structure and Thermal Conductivity of Foamed Polymers Thermal Conductivity of the Polymer Phase Thermal Conductivity of the Gas Phase Radiative Thermal Conductivity Convective Thermal Conductivity Effects of Variables on the Thermal Conductivity General Concepts Three Generations of Polymer Foams Six Structural Levels Quantitative Parameters of Cellular Structure Technological Concepts Advantages of Foamed Polymers References 52 4 Flexible Polyurethane Foams Introduction Applications Markets Basic Chemistry The Polymerization Reaction The Gas-Producing Reaction Foam Recipe Components Foam Morphology Review of Current Concepts Model for Flexible Foam Formation Preparation of Flexible Foam General Requirements Laboratory-Scale Cup-Foaming Laboratory Box-Foams Machine-Made Foam Mixing Heads Commercial-Scale Processes Foam Physical Properties Foam Density Load Bearing Airflow Cell Size Compression Set Tension Properties Tear Resilience Slabstock Foams Slabstock Chemistry Alternative Blowing Agent Developments High Load Bearing Foams High Resilience Foams 102

4 Contents XIII Foam Flammability Non-BHT Foams Emanations Recycling Molded Foam Seating Foams Comfort Durability Fogging and Odor References Rigid Polyurethane Foams Introduction Structure Chemistry Reactants Isocyanates Polyols Catalysts Stabilizers Blowing Agents Combustion Modifiers Formulations Foam Preparation Block and Sheet Pour-in-Place Spray Foam Physics Properties Density Mechanical Properties Water, Solvent, and Chemical Resistance Thermal Conductivity Combustibility Applications Health and Safety Isocyanates Polyols Catalysts Blowing Agents Future Trends References 138 Acknowledgement Polyisocyanurate Foams Introduction Isocyanurate Chemistry Catalysts for Cyclotrimerization 143

5 XIV Contents Kinetics and Mechanisms of Cyclotrimerization Relative Catalytic Activity Preparation of Modified Polyisocyanurate Foams Urethane-Modified Polyisocyanurate Foams Oxazolidone-Modified Polyisocyanurate Foams Amide-Modified Polyisocyanurate Foams Carbodiimide-Modified Polyisocyanurate Foams Imide-Modified Polyisocyanurate Foams Applications Composite Foam Boards Flame-Retardant Seamless Insulation [61] Building Insulation Chemical and Petrochemical Plant Insulation High-Rise Building Walls Chemical-Resistant Floats Cryogenic, Petrochemical, and Solar Energy Applications Highly Resilient Flexible Polyurethane Foams References Polystyrene and Structural Foam Introduction and General Description Nomenclature Chemistry and Preparation Theory of the Expansion Process Blowing Agent Selection Properties and Their Relation to Structure Test Methods Properties of Commercial Products Mechanical Properties Thermal Properties Moisture Resistance Electrical Properties Environmental Aging Other Properties Commercial Production and Processing Manufacturing Process Commercial Products and Processes Applications Cushioning Thermal Insulation Packaging Structural Components Marine Applications Electrical Insulation Space Filling and Seals Other Uses Energy Considerations in Foam Insulation 220

6 Contents XV Health and Safety Factors References Polyolefin Foam Introduction Chemistry and Preparation Foam Expansion with a Physical Blowing Agent Foam Expansion with a Chemical Blowing Agent Properties and Their Relation to Structure Properties of Commercial Products Relationships Between Structure and Properties Commercial Production and Processing Extrusion Processes Processes for Manufacturing Moldable Polyolefin Beads Cross-Linked Polyolefin Foam Sheet Processes Cross-Linked Polyolefin Foam Bun Stock Processes Applications Fabrication Major Applications References PVC Foams Introduction Characteristics of PVC PVC Structures Structure Changes During Processing Influence of PVC Fusion on Physical Properties Formulation Technology Overview of Formulas for PVC Foam Effects of Formulation Ingredients on the Foaming Process and Properties of Foamed Products Use of Recycled PVC in Foam Formulations Design of Experiment (DOE) for Foam Formulation Development Processing Technology Extrusion of PVC Foams Injection Molding of PVC Foams Foaming of PVC at Atmospheric Pressure Microcellular PVC Foams PVC/Wood Flour Composite Foams Mechanical Property Analyses and Test Standards Mechanical Properties ASTM and ISO Standards References Epoxy Foams Introduction Epoxy Chemistry and Formulations Blowing or Foaming Agents and Processes 349

7 XVI Contents Inert Gas Blowing Agents Inert Liquid Blowing Agents Reactive Blowing Agents Expanding Syntactic Fillers Frothed Epoxies Epoxy Emulsions Non-Aqueous Liquid Extractable Pore Formers and CIPS Solid Extractable Pore Formers Stereolithography Combinations of Epoxy and Isocyanate Based Thermosets Three-Phase Syntactics Fiber-Reinforced Foams Removable Foams Applications Automotive (also See Adhesive Applications Below) Electronics Encapsulation Adhesives Building Retrofitting Dams, Tanks and Bridges Expanding Cores Sports Equipment Personal Care Products Thermoplastic Processing and Recycling lOLung Substitutes References Latex Foam and Sponge Introduction Dunlop Process Compounding Ingredients Processing Notes Foaming Freeze Process Original Freeze Process Newer Freeze Process Sponge Open-Cell Sponge Rubber Closed-Cell Sponge Rubber References Silicone Foams Background and Development Background Development of Silicone Foams Development of Flame-Retardant Foam Technology Chemistry and Preparation Foam Formation Optional Ingredients 381

8 Contents XVII Preparation Properties and Their Relationship to Structure Structural Features Physical Properties Commercial Production and Processing Metering Mixing Dispensing Equipment Selection Applications Foam Applications Forms of Foam Features of Silicone Products Areas of Application References Fluoropolymer Foams History and Introduction Chemistry and Physics of Foam Preparation Nucleation and Bubble Growth Properties and Their Relation to Cell Structure Physical Properties Thermal Properties Specific Heat Electrical Properties Commercial Production and Processing Foaming of FEP and PFA Resins Foaming of Fluoroelastomer Resins (such as Viton) Expansion of PTFE Resin Applications References Wood Flour Composite Foams Introduction Background on Polymeric Composites Natural Fibers and Their Properties Plastic/Wood Flour Composite Foams Major Issues in Development of PWC Foams Thermal Degradation of Natural Fibers Moisture Content and Volatile Emissions from Natural Fibers Dispersion of Natural Fiber and Fiber-Matrix Bonding Processing Difficulties Due to Increased Viscosity Phase Changes in Foaming of PWC Changes in Phase Morphology of the Extrudate During Microcellular Foaming and Fine-Celled PWC Foaming Polymer/Gas Solution Formation Cell Nucleation Cell Growth Control 424

9 XVIII Contents 14.4 Experiments and Discussion Effects of Volatile Emissions from Wood Flour During Extrusion Processing Foaming Experiments with Varying Content of Extractives Critical Processing Temperature in Extrusion Processing of PWC Foams Foaming with Various CBAs Conclusions References Phenolic Foams Chemistry and Foam Formation Phenolic Resins Crosslinking of Phenolic Resins Foam Formation Reduction in Corrosivity of Phenolic Foam Properties and Their Relation to Structure Commercial Production and Processing Applications References Flame Retardancy of Polymeric Foams Introduction The Combustion of Polymeric Foams Flame Combustion of Polymeric Foams Smoldering Combustion of Polymeric Foams Filtration Combustion of Gases in Polymeric Foams Test Methods and Fire Safety Classification Parameters 463 of Foamed Materials for the Assessment of Fire Hazards Recent Advances in Flame Retardancy of Polymeric Foams The Development of Foams Based on Inherently Thermally Stable and Flame Retardant Polymers Chemical and Physical Modification of Polymeric Foams Additive Flame Retardants References Syntactic Polymer Foams Introduction Hollow Sphere Fillers General Information Glass Microspheres Polymeric Microspheres Miscellaneous Other Microspheres Macrospheres Syntactic Foam Processing General Considerations Rheology of Syntactic Mixtures Casting and Molding Compositions 483

10 Contents XIX Regulating the Apparent Density Microsphere Space Factors and Packing Syntactic Foam Production Epoxy Syntactic Foams Oligoester Syntactic Foams Phenolic Syntactic Foams Organosilicone Syntactic Foams Polyimide Syntactic Foams Carbonized Syntactic Foams Syntactic Prepregs Miscellaneous Syntactic Foams Physical Properties of Syntactic Foams Strength Properties Water Absorption and Resistance to Hydrostatic Pressure Thermal Properties Recent Developments and Main Applications Sub-Sea and Shipbuilding Applications Structural Applications Aerospace Applications Other Applications References Blowing Agents for Polymeric Foams Introduction Classification Chemical Blowing Agents Main Characteristics Inorganic Blowing Agents Organic Blowing Agents Blowing Agents that Liberate Gases as a Result of Chemical Interaction between the Components Practical Guide for Selection of CBAs Physical Blowing Agents and Environmental Problems Main Characteristics Volatile Liquids Solid Blowing Agents Gases Nucleazites References 547 Appendix Letters of the Roman Alphabet 549 Capital Greek Letters 550 Lower Case Greek Letters 551 Appendix Conversion Factors between English and S.I. Units for Quantities Used in Describing the Physical Properties of Foams 552