Handbook of Adhesives and Surface Preparation

Technology, Applications and Manufacturing

Sina Ebnesajjad

• Publisher: William Andrew
• Year: 2010
• ISBN:
  9781437744620
• Topic: Scienze fisiche
• Subtopic: Fisica

Handbook of Adhesives and Surface Preparation provides a thoroughly practical survey of all aspects of adhesives technology from selection and surface preparation to industrial applications and health and environmental factors. The resulting handbook is a hard-working reference for a wide range of engineers and technicians working in the adhesives industry and a variety of industry sectors that make considerable use of adhesives. Particular attention is given to adhesives applications in the automotive, aerospace, medical, dental and electronics sectors.

• A handbook that truly focuses on the applied aspects of adhesives selection and applications: this is a book that won't gather dust on the shelf
• Provides practical techniques for rendering materials surfaces adherable
• Sector-based studies explore the specific issues for automotive and aerospace, medical, dental and electronics

1. Introduction and Adhesion Theories

Sina Ebnesajjad

1.1. Definition of Adhesives and Adhesive Bonding

An adhesive is a material that is applied to the surfaces of articles to join them permanently by an adhesive bonding process. An adhesive is a substance capable of forming bonds to each of the two parts when the final object consists of two sections that are bonded together. ¹ A feature of adhesives is the relatively small quantities that are required compared to the weight of the final objects.

Adhesion is difficult to define, and an entirely satisfactory definition has not been found. The following definition has been proposed by Wu. ²“Adhesion refers to the state in which two dissimilar bodies are held together by intimate interfacial contact such that mechanical force or work can be transferred across the interface. The interfacial forces holding the two phases together may arise from van der Waals forces, chemical bonding, or electrostatic attraction. Mechanical strength of the system is determined not only by the interfacial forces, but also by the mechanical properties of the interfacial zone and the two bulk phases.”

There are two principal types of adhesive bonding: structural and nonstructural. Structural adhesive bonding is bonding for applications in which the adherends (the objects being bonded) may experience large stresses up to their yield point. Structural adhesive bonds must be capable of transmitting stress without losing of integrity within design limits. ³ Bonds must also be durable throughout the useful service life of a part, which may be years. In addition to possessing significant resistance to aging, a structural bond is defined as having a shear strength greater than 7 MPa. Nonstructural adhesives are not required to support substantial loads but merely hold lightweight materials in place. This type of adhesive is sometimes called a “holding adhesive.” Pressure-sensitive tapes and packaging adhesives are examples of nonstructural adhesives.

The distinction between structural and nonstructural bonds is not always clear. For example, is a hot melt adhesive used in retaining a fabric's plies structural or nonstructural? One may argue that such an adhesive can be placed in either classification. However, the superglues (cyanoacrylates) are classified as structural adhesives even though they have poor resistance to moisture and heat.

1.2. Functions of Adhesives

The primary function of adhesives is to join parts together. Adhesives accomplish this goal by transmitting stresses from one member to another in a manner that distributes the stresses much more uniformly than can be achieved with mechanical fasteners. Adhesive bonding often provides structures that are mechanically equivalent to or stronger than conventional assemblies at lower cost and weight. In mechanical fastening, the strength of the structure is limited to that of the areas of the members in contact with the fasteners. ⁴ Obtaining adhesive bonds that are stronger than those of the strength of adherends is not unusual.

Smooth surfaces are an inherent advantage of adhesively joined structures and products. Exposed surfaces are not defaced and contours are not disturbed, as happens with mechanical fastening systems. This feature is important in function and appearance. Aerospace structures, including helicopter rotor blades, require smooth exteriors to minimize drag and to keep temperatures as low as possible. Lighter weight materials than are used with conventional fastening can often be used with adhesive bonding because the uniform stress distribution in the joint permits full utilization of the strength and rigidity of the adherends. ⁴ Adhesive bonding provides much larger areas for stress transfer throughout the part, thereby decreasing stress concentration in small areas.

Dissimilar materials, including plastics, are readily joined by many adhesives, provided that proper surface treatments are used. Adhesives can be used to join metals, plastics, ceramics, cork, rubber, and combinations of materials. Adhesives can also be formulated to be conductive. The focus of this book is on adhesives for bonding plastics, thermosets, elastomers, and metals.

Where temperature variations are encountered in the service of an item containing dissimilar materials, adhesives perform another useful function. Flexible adhesives are able to accommodate differences in the thermal expansion coefficients of the adherends, and therefore prevent damage that might occur if stiff fastening systems were used.

Sealing is another important function of adhesive joining. The continuous bond seals out liquids or gases that do not attack the adhesive (or sealant). Adhesives/sealants are often used in place of solid or cellular gaskets. Mechanical damping can be imparted to a structure through the use of adhesives formulated for that purpose. A related characteristic, fatigue resistance, can ...

Table of contents

• Cover Image
• Table of Contents
• PDL Handbook Series
• Front Matter
• Copyright
• Acknowledgments
• Dedication
• Preface
• 1. Introduction and Adhesion Theories
• 2. Introduction to Surface Preparation and Adhesion
• 3. Surface Tension and Its Measurement
• 4. Surface and Material Characterization Techniques
• 5. Material Surface Preparation Techniques
• 6. Surface Preparation of Metals
• 7. Surface Preparation of Thermoplastics, Thermosets, and Elastomers
• 8. Characteristics of Adhesive Materials
• 9. Heat-Resistant Adhesives
• 10. UV-Radiation Curing of Adhesives
• 11. Adhesives for Special Adherends
• 12. Adhesives for Electronics
• 13. Adhesives for Aerospace Structures
• 14. Adhesives for Medical and Dental Applications
• 15. Adhesion Promoters
• Appendix A. Safety, Environmental, and Economic Aspects and Future Trends
• Guidance for Industry and FDA Staff
• Glossary
• Index