What is adhesive? What are the main physical properties and testing standards of adhesives?

What is adhesive?

The use of adhesives is used in all aspects of life and production, such as adhesives for electronic components, adhesives for automotive interior parts, adhesives for packaging materials, surface bonding of shoe materials and other construction or decorative materials; then what are adhesives? What are the main physical properties and testing standards of adhesives?
Adhesion (bonding, bonding, gluing, gluing) refers to the technology in which the surfaces of homogenous or dissimilar objects are joined together with an adhesive, which has the characteristics of continuous stress distribution, light weight, or sealing, and low temperature for most processes. Adhesive bonding is especially suitable for the connection of different materials, different thicknesses, ultra-thin specifications and complex components.
A class of natural or synthetic, organic or inorganic substances that can connect two or more parts or materials through interfacial adhesion and cohesion, collectively referred to as adhesives, also known as adhesives , customarily referred to as glue. In short, an adhesive is a substance that binds the adherends together through adhesion. “Adhesive” is a generic standard term.

Main physical properties of adhesive

  1. Operation time
    Maximum time interval between adhesive mixing and pairing of parts to be bonded
  2. Initial curing time
    Time to Removable Strength Allows Adequate Strength for Handling Bonds, including Moving Parts from Fixtures
  3. Complete curing time
    Time required to achieve final mechanical properties after adhesive mixing
  4. Storage period
    Under certain conditions, the adhesive can still maintain its handling properties and the storage time of the specified strength
  5. Bonding strength
    Under the action of external force, the stress required to make the interface between the adhesive and the adherend in the adhesive part break down or its vicinity
  6. Shear strength
    Shear strength refers to the shear force that the unit bonding surface can withstand when the bonding part is damaged, and its unit is expressed in MPa (N/mm2)
  7. Uneven pull-off strength
    The maximum load that the joint can bear when subjected to uneven pull-off force, because the load is mostly concentrated on two edges or one edge of the adhesive layer, and the force is per unit length rather than per unit area, and the unit is KN/m
  8. Tensile strength
    Tensile strength, also known as uniform pull-off strength and positive tensile strength, refers to the tensile force per unit area when the adhesive is damaged by force, and the unit is expressed in MPa (N/mm2).
  9. Peel strength
    Peel strength is the maximum load per unit width that can withstand when the bonded parts are separated under the specified peeling conditions, and its unit is expressed in KN/m

Common test items for adhesives

  1. Physical properties
    General properties: thickness; viscosity; water resistance
    Mechanical Testing: Tensile Properties; Peel Strength; Tensile Shear Strength; Compressive Shear Strength; Horizontal and Vertical Tack
    Burning performance: horizontal burning; vertical burning; glow wire burning
    Electrical properties: surface and volume resistivity of insulating materials; surface resistivity of anti-static materials; dielectric strength, breakdown voltage; withstand voltage
  2. Aging test
    Rapid UV aging; xenon lamp aging; temperature and humidity aging; salt spray aging; appearance and performance evaluation after aging
  3. Component analysis
    Principal component qualitative analysis; full component qualitative analysis; full component quantitative analysis; ash content
  4. Reliability
    Temperature and humidity cycle; temperature shock; waterproof and dustproof; vibration test

Current relevant standards for adhesives

  1. GB 18581-2009 Limits of Hazardous Substances in Solvent-Based Wood Coatings for Interior Decoration Materials
  2. GB/T 2791-1995 Adhesive T peel strength test method flexible material to flexible material
  3. GB/T 27934.3-2011 Process control and testing methods for lamination of paper printed matter
  4. GB/T 2794-2013 Determination of Adhesive Viscosity Single Cylinder Rotational Viscometer Method
  5. GB/T 16585-1996 Vulcanized rubber artificial weathering (fluorescent ultraviolet lamp) test method
  6. GB/T 7124-2008 Adhesive Shear Strength
  7. ASTM D 1781-1998 Adhesive Roller Peel Test Method

Adhesives are widely used in various fields of the national economy and have become indispensable for the development of the national economy due to their advantages of realizing the connection of the same or dissimilar materials, no stress concentration at the joint, high bonding strength, and easy to realize automatic chemical operation. chemical products.

What is the above ie adhesive? What are the main physical properties and testing standards of adhesives? For more information about adhesives, log in to the Thermal Adhesives Network (www.coolthermo.com) to inquire!

A New Choice for Thermal Management – Thermal pad

With the development of industrial production and technology, people continue to put forward new requirements for materials. In the field of electronic appliances, due to the rapid development of integration technology and assembly technology, electronic components and logic circuits are developing in the direction of lightness, thinness and smallness, and the heat is also increased. High thermal conductivity insulating materials are required to effectively remove the heat generated by electronic equipment, which is related to the product’s heat. Service life is related to quality reliability.

The commonly used cooling methods in the past are: natural cooling, ventilation or the use of larger cabinets. As the heating area becomes wider and wider, the heat generated is also increasing, forcing electronic equipment manufacturers to take more effective cooling measures. Thermal interface materials also came into being.

thermal pad

Thermally conductive gasket is one of thermal interface materials. Broadly speaking, it refers to a sheet-like object that can conduct heat. Such objects can be metal plates, epoxy thermally conductive sheets, thermally conductive plastics, thermally conductive rubber, etc.; For example, we will use the silicone rubber material as the basic frame and the sheet-like thermally conductive insulating silicone rubber material filled with the thermally conductive material as the thermally conductive gasket, also known as the thermally conductive silicone rubber.

As one of thermal interface materials, thermal pads have obvious advantages compared with other thermal interface materials.

First of all, the thermal conductive gasket is compressible, soft and elastic, and has the function of buffering and shockproof for the application environment under low pressure;

Secondly, thermal pads have a certain self-adhesiveness. For applications that do not require high viscosity, there is no need to apply adhesive on the surface of thermal pads;

Third, different from other thermal interface materials such as thermally conductive silicone grease, thermally conductive potting glue and thermally conductive phase change materials, thermally conductive gaskets can be easily reused, which is very important for installation and testing;

Fourth, the thickness of the thermal pad is optional. For different gaps, thermal pads with different thicknesses can be selected, that is to say, the thermal pad has a wider application environment;

Finally, it should be emphasized that the thermal conductivity of the thermal pad is very stable, and the thermal conduction effect will not be affected by the increase or decrease of the thickness, which is very different from thermal grease.

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