Structural Adhesives

I. Definitions.- A. Structural Adhesives.- B. Classification.- C. Organization of Book.- D. Units and Conversion Factors.- II. Background.- A. Structural Bonding.- 1. Joining Methods.- 2. Advantages of Structural Adhesives.- 3. Limitations of Structural Adhesives.- B. Principles of Structural Bonding.- 1. Surface and Interfacial Phenomena.- 2. Phase Change.- 3. Bond Failure.- C. Design of Adhesive Joints.- D. Testing.- E. Adhesive Selection.- III. Markets for Structural Adhesives.- A. Adhesive Markets.- B. Markets for Structural Adhesives.- 1. Transportation.- 2. Construction.- 3. Other Rigid Bonding.- 4. Consumer Products.- IV. Applications.- References.- 1. Fundamentals of Structural Adhesive Bonding.- I. Introduction.- II. Physical Properties of Polymers and Adhesives.- A. Stress-Strain Properties.- B. Dynamic Mechanical Properties.- III. Surface Energy and Aspects of Cohesion.- A. Thermodynamics.- B. Cohesive Strength.- C. Fracture Mechanics for Linear Elastic Solids.- IV. Theories of Adhesion.- A. Introduction.- B. Wettability/ Adsorption Theory.- C. Contact Angles and Wettability.- D. Components of Surface and Interfacial Tension.- E. van der Waals Forces.- F. Kinetics of Wetting.- G. Mechanical Interlocking.- H. Chemical Bonding at Interfaces.- I. Acid-Base Interactions.- J. The Diffusion Theory of Adhesion.- V. Criteria for Optimum Bond Strength.- References.- 2. Phenolic Resins.- I. Introduction.- II. Mechanism of Phenol-Formaldehyde Reactions.- A. Reactions under Strongly Acidic Conditions (pH 1-4).- B. Reactions under Weakly Acidic Conditions (pH 4-7).- 1. High ortho-ortho Novolacs.- 2. Superacidity.- 3. High ortho-ortho Resoles.- 4. Dibenzylic Ether Linkages.- 5. Cyclic Polynuclear Species.- C. Reactions under Basic Conditions (pH 7-11).- 1. Resoles.- 2. Self-condensation.- D. Resorcinol and m-Aminophenol Modified Phenolic Resins.- E. Modified Phenolic Resins.- 1. Etherified Resoles.- 2. Modification at the Phenolic Hydroxyl.- III. Curing Reactions.- A. Curing of Resoles.- B. Curing of Novolacs.- C. Thermal Degradation.- IV. Structural Phenolic Adhesives.- A. Introduction.- B. Phenolic Resins for Wood Bonding.- 1. Phenolic Resins.- 2. Resorcinol Modified Novolacs.- 3. m-Aminophenol Modified Novolacs.- C. Polymer Blends for Metal Bonding.- 1. Phenolic-Epoxy Blends.- 2. Phenolic-Polyvinyl Blends.- 3. Phenolic-Nitrile Blends.- 4. Polyamide Phenolics.- 5. Nylon Phenolics.- 6. Acrylic Phenolics.- 7. Neoprene Phenolics.- 8. Urethane Phenolics.- D. Cure Conditions and Properties.- E. Commercially Available Materials.- References.- 3. Epoxy Structural Adhesives.- I. Introduction.- II. Compounding Epoxy Structural Adhesives.- A. Overview of Adhesives and Epoxy Raw Materials.- B. Two-Part Room Temperature Curing Epoxy Adhesives.- 1. Nitrogen-containing Curatives.- 2. Sulfur-containing Curatives.- 3. Carboxyl-containing Curatives.- 4. Lewis Acid Catalysts.- 5. Encapsulation.- C. One-Part Heat Curing Paste Adhesives.- 1. Catalysts.- 2. Toughening Agents.- 3. Fillers, Filler Treatments, and Surfactants.- 4. Thixotropic Additives.- 5. Adhesion Promoters.- D. Epoxy Film Adhesives.- III. Recent Developments in Epoxy Structural Adhesives.- A. Epoxy Resins.- B. Room Temperature Amine Curing Agents.- C. Room Temperature Sulfur Curing Agents.- D. Room Temperature Acid Catalysts.- E. Heat Cure Amine Curatives and Catalysts.- 1. Primary Amine Curatives.- 2. Secondary Amine Curatives.- 3. Tertiary Amine Catalysts.- 4. Dicyandiamide and Derivatives.- 5. Imidazole Derivatives.- F. Heat Cure Carboxylic Acid Curatives.- G. Heat Cure Anhydride Curatives.- H. Heat Cure Cationic Catalysts.- I. Flexibilizing and Toughening Agents.- 1. Flexibilizing Agents.- 2. Toughening Agents.- J. Fillers.- 1. Reinforcing Fillers.- 2. Glass Fillers.- 3. Corrosion-inhibiting Fillers.- 4. Adhesion-promoting Fillers.- 5. Cure-promoting Fillers.- 6. Electrical Conductivity-promoting Fillers.- 7. Silica Fillers.- 8. Flow Control Fillers.- K. Additives.- 1. Adhesion Promoters.- 2. Adhesive-strengthening Additives.- 3. Heat and/ or Moisture Resistance Additives.- 4. Film-forming Additives.- 5. Dispersing Additives.- References.- 4. Polyurethane Structural Adhesives.- I. Introduction.- II. Polyurethane Chemistry.- III. Structure-Property Relationships in Polyurethanes.- A. General Concepts.- B. Effect of Soft Segment.- C. Effect of Hard Segment.- D. Chemical Crosslinking.- E. Stability of Polyurethanes.- 1. Thermal Stability.- 2. Oxidative Stability.- 3. Solvolytic Stability.- 4. Stabilization.- IV. Polyurethane Structural Adhesive Applications.- A. Introduction.- B. Two-Part Adhesives.- C. One-Part Adhesives.- 1. Moisture Cure.- 2. Heat Cure.- D. Comparison of One-Part and Two-Part Systems.- E. Plastic and Metal Bonding.- 1. Trends.- 2. Substrate Preparation.- 3. Bond Testing.- F. Wood Bonding.- References.- 5. Anaerobic and Structural Acrylic Adhesives.- I. Introduction.- II. Anaerobic Adhesives.- A. Background.- B. Formulation Components.- 1. Monomers.- 2. Initiators.- 3. Accelerators.- 4. Stabilizers/ Inhibitors.- 5. Modifiers.- C. Chemistry of Anaerobic Adhesives.- D. End Use Applications.- E. Anaerobic Products and Performance.- III. Structural Acrylic Adhesives.- A. Background.- B. Formulation Components.- 1. Monomers.- 2. Catalyst Systems.- 3. Tougheners.- C. Chemistry.- D. Applications.- E. Commercial Product Performance.- References.- 6. Cyanoacrylate Adhesives.- I. Introduction.- II. Cyanoacrylate Chemistry.- A. General Description.- B. Monomer Synthesis.- 1. Alkyl Cyanoacrylates.- 2. Biscyanoacrylates.- 3. 2-Substituted-l-Cyanoacrylates.- C. Properties of Cyanoacrylate Monomers.- D. Polymerization of Cyanoacrylate Monomers.- 1. Introduction.- 2. Initiation.- 3. Propagation.- 4. Chain Transfer and Termination.- 5. Bulk Polymerization.- E. Polymerization Modifiers.- 1. Initiators.- 2. Accelerators.- 3. Inhibitors.- F. Properties of Polycyanoacrylates.- III. Cyanoacrylate Adhesive Properties.- A. Bond Strength.- 1. Introduction.- 2. Bond Strength Modifiers.- B. Durability.- 1. Introduction.- 2. Heat Durability.- 3. Heat Resistance Promoters.- 4. Moisture Durability.- C. Other Adhesive Properties and Modifiers.- 1. Viscosity.- 2. Colorants and Dyes.- 3. Miscellaneous Properties and Modifiers.- IV. Cyanoacrylate Application and Uses.- A. Bondable Substrates.- B. Surface Preparation.- 1. Metals.- 2. Polymers.- 3. Glass and Ceramics.- 4. Wood.- C. Toxicology and Safety.- 1. Handling Precautions.- 2. Toxicology.- D. Containers and Storage.- E. Application Methods and Equipment.- 1. Adhesive Application.- 2. Application Equipment.- F. Typical Industrial Applications.- V. Summary.- A. Advantages of Cyanoacrylate Adhesives.- B. Disadvantages of Cyanoacrylate Adhesives.- C. A Comparison of Cyanoacrylates with Other Adhesives.- D. A Summary of Recent Improvements to Cyanoacrylate Adhesives.- References.- 7. High-Temperature Polymers and Adhesives.- I. Introduction.- II. High-Temperature Polymers.- A. Theory of Thermal Stability.- B. Measurement of Thermal Stability.- C. Heat-Resistant Polymers.- 1. Aromatic Conjugated Polymers.- 2. Ladder Polymers.- 3. Stepladder Polymers.- 4. Aromatic Linked by Aliphatic or Functional Group.- III. High-Temperature Adhesives.- A. Condensation-Type Adhesives.- 1. Polyimides.- 2. Polyphenylquinoxaline.- B. Addition-Type Adhesives.- 1. Norbornene End Groups.- 2. Acetylene End Groups.- 3. Maleimide End Groups.- C. Thermoplastic Adhesives.- D. Miscellaneous Other Polymers for Adhesive Applications.- IV. Bonding Technology of High-Temperature Adhesives.- A. Substrates and Surface Preparation.- 1. Surface Preparation of Titanium.- 2. Surface Preparation of Aluminum and Other Adherends.- B. Comparative Properties of High-Temperature Adhesives.- V. Applications of High-Temperature Adhesives.- A. General Considerations.- B. Applications.- 1. Aerospace.- 2. Electronics.- 3. Electrical.- 4. Automotive.- 5. Miscellaneous.- VI. Trends and Conclusions.- References.- 8. The Durability of Structural Adhesive Joints.- I. Introduction.- II. Factors Affecting Durability.- A. Nature of the Adhesive.- 1. General Considerations.- 2. Resistance to Hydrolysis.- 3. Mechanical Properties.- 4. Effect of Adhesive Formulation.- 5. Adhesives for Aluminum.- 6. Adhesives for Wood.- 7. Other Structural Adhesives.- B. Nature of the Adherends.- 1. Metal Adherends.- 2. Wood Adherends.- 3. Plastic Adherends.- 4. Thermal Stability of the Adhesive.- 5. Hydrolytic Stability of the Adhesive.- 6. Cure of the Adhesive.- C. Nature of the Surface.- 1. Effect of Surface Preparation.- 2. Characterization of Oxide Layer Structure.- 3. Hydration of Oxide Layer.- 4. Stabilization of the Oxide Interface.- D. Environmental Conditions.- E. Processing Conditions.- III. The Effect of Water.- A. Uptake of Water.- 1. Diffusion Coefficients.- 2. Equilibrium Water Uptake.- 3. Uptake of Water by an Adhesive Joint.- B. Effect of Water on Joint Strength.- C. Effect of Water on Joint Durability.- 1. Thermodynamic Considerations.- 2. Irreversible Effects.- 3. A Mechanism for Environmental Failure of Adhesive Bonds.- IV. Assessment of Durability.- A. Sustained Load Methods.- 1. Individual Specimens.- 2. Multiple Specimens.- B. Endurance Limit.- C. Cyclic Stress Testing.- D. Hot Water Soak.- E. Fracture Mechanics Tests.- 1. Fracture Energy.- 2. Failure under Sustained Loads.- 3. Cyclic Loading.- F. Prediction of Service Life.- 1. Reaction Rate Method.- 2. Statistical Approaches.- V. Summary.- References.- 9. Testing, Analysis, and Design of Structural Adhesive Joints.- I. Introduction.- II. Mechanical Testing of Adhesive Joints.- A. Introduction.- B. Tensile Tests.- C. Shear Tests.- 1. Lap Shear Tests.- 2. Compressive Shear Tests.- 3. Torsional Shear Test.- D. Peel Tests.- E. Other Tests.- III. Stress Analysis of Adhesive Joints.- A. Introduction.- B. Tensile Loads.- C. Shear Loads.- D. Peel Loads.- IV. Fracture Mechanics of Adhesive Joints.- A. Introduction.- B. Fracture Mechanics Theories.- C. Fracture Mechanics Applied to Adhesive Joints.- V. Adhesive Joint Design.- A. Introduction.- B. Butt Joints.- C. Lap Joints.- D. Scarf and Modified Joints.- E. Design Criteria.- VI. Summary.- References.- 10. Industrial Application Methods.- I. Introduction.- II. Factors Affecting the Choice of a Method of Application.- A. Adhesive Properties.- 1. Physical Form.- 2. Curing Mechanism.- B. Substrate Properties.- 1. Material.- 2. Condition.- 3. Shape.- C. Conditions of Manufacture.- III. Application Methods and Equipment.- A. Dispensing.- 1. Liquids and Pastes.- 2. Films.- 3. Powders.- B. Handling Multiple-Component Adhesives.- 1. Pumps.- 2. Hoses.- 3. Mixers and Valves.- 4. Cleaning.- C. Heat Curing.- 1. Hot Air Ovens.- 2. Localized Hot Air.- 3. Infrared Ovens.- 4. Localized Infrared.- 5. Electrical Induction.- 6. RF and Microwave Energy.- 7. Hot Oil Baths.- 8. Condensing Vapors.- 9. Autoclaves.- 10. Hot Platen Press.- IV. Conclusion.- Appendix I: Standard Definitions of Terms Relating to Adhesives.- Appendix II: SI Units and Conversion Factors.- Appendix III: ASTM Standards Relating to Adhesives.