The functional requirements of adhesive joints are multifaceted, generally including mechanical strength, heat resistance, oil resistance, waterproofness, conductivity and other characteristics, as well as environmental stress resistance. The selected adhesive must also have corresponding functions. The following introduces the relevant adhesives according to typical functional requirements.

1. Mechanical strength

This type of adhesive should have good mechanical strength, including tensile strength, shear strength, and peel strength. Commonly used adhesives are epoxy resin adhesives, but their peel strength is poor. If epoxy-nitrile adhesives and phenolic-nitrile adhesives are used, satisfactory results can be obtained. In the repair of machine tool guide rail wear, wear-resistant adhesives are required. AR-5 wear-resistant adhesive can be used. Its hardness reaches 11.8HB. It is composed of epoxy resin and inorganic fillers. For plastic carpets and beverage bottle labels, adhesives require higher shear strength and lower peel strength.

2. Heat resistance

Generally, the long-term use temperature of polymer adhesives is below 200°C. However, in the special use of some materials, the long-term use temperature is required to be above 200°C. For example, the adhesive in microelectronic components must be bonded to the 400°C substrate in an inert atmosphere; the structural adhesive used in supersonic flight is required to be used for tens of thousands of hours at 230°C; the adhesive used on missiles is required to maintain mechanical properties for more than 1 minute at 540°C. These are all special adhesives for special purposes.

3. Oil resistance

The bonding of oil pipeline joints and parts in lubricating oil requires the adhesive to be bonded in an oily and humid environment, where surface treatment is not possible, and to obtain sufficient strength.

4. Water resistance

Generally speaking, polar adhesives are more hydrophilic, and the joint strength will drop sharply in a humid environment.

5. Optical properties

In addition to having a certain bonding strength, the adhesive used for optical parts must also meet the requirements of light transmittance, which is generally above 90%.

6. Other functions

The functional requirements of adhesive joints are diverse, such as electromagnetic, acoustic and physiological effects.