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Kluwer Academic Structural Adhesives Chemistry And Technology 1986 Edition by S.R. Hartshorn
Adhesives in general and structural adhesives in particular are the subjects of much academic interest as well as commercial importance. Structural bonding as a method of joining offers a number of advantages over mechanical fastening. However in order to achieve satisfactory results the proper adhesive must be selected and the appropriate bonding procedures followed. The purpose of Structural Adhesives: Chemistry and Technology is to review the major classes of structural adhesives and the principles of adhesion and bonding as these relate to structural joints. Each chapter provides an overview of the topic under discussion with a list of references to the relevant literature. In addition to describing the chemistry involved other aspects of structural adhesive technology are covered such as formula- tion testing and end uses. Some structural adhesives especially epoxies and phenolics have a long history of successful use and are now widely employed. Others such as the structural acrylics and cyanoacrylates are beginning to gain industrial acceptance.Urethanes and anaerobics have limited but important uses while high-temperature adhesives are still largely in the research and development stage. Table of contents : 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.show more