Adhesive Bonding

1
Adhesive Bonding

• Used to bond two or more different materials
  together

2
Grouping Adhesives

• Arranged by their use 1. nonstructural, 2.
  structural
• Nonstructural does not support a load. Examples
  are glues and cements.
• Structural can withstand a load over a long
  period of time. These include thermoplastics,
  thermosets, adhesive alloys, elastomers, metal
  alloys.

3
Organic and Synthetic

• Organic adhesives are compounds in which carbon
  and hydrogen form the base of the adhesive and
  can be traced back to living things. Early
  examples used animal hide, fish, and casein or
  milk glues. Starch and Soya flour were also
  used.
• Synthetic adhesives are human made. They adhere
  to the base material and they change from a
  liquid to a solid to form a bond (except for
  pressure sensitive adhesives). Many have a
  hardener and a catalyst to speed up curing time.
  Most also have a solvent which suspends the
  adhesive with other components and allows the
  adhesive to spread. Fillers and diluents are
  also used to strengthen and allow workability of
  the adhesive. Synthetic adhesives are made up of
  polymers.

4
Thermoplastic Adhesives

• These adhesives contain a basic tackiness and are
  softened by heat and often when exposed to water.
  
• The glue joint is somewhat flexible and soft.

5
Thermosetting Plastics

• These adhesives develop their adhesive bonding
  characteristics during a curing process causing
  the material to polymerize into long-chain
  organic molecules producing a adhesive bond.
• Does not soften when heated and a brittle join is
  produced.

6
Polymerization of a Thermoset

• Polymerization can be caused by the following
• Plural components The chemical action is started
  by mixing the adhesive material with the curing
  agent.
• Heat the chemical action is started by an
  outside heat source.
• Moisture The chemical action is started with
  moisture in the air or the base material. These
  are quick setting adhesives.

7
Adhesive Alloys

• These are a mix of adhesive materials. Usually
  thermosetting materials.
• Provide great strength, creep resistance, and
  resistant to the environment.
• Examples include epoxy/nylon, epoxy/phenolic,
  and epoxy/polysulfide.

8
Elastomers

• Nonstructural adhesives.
• Consist of natural and synthetic rubber material.
  They can stretch over twice their normal length.
  
• Often solvent based and are low creep resistant.
• Examples include contact cement and adhesives for
  bonding paneling, drywall, flooring, and ceramic
  tile. Pressure-sensitive tape and paper are
  coated with elastomers.

9
Metal Alloy Adhesives

• Use an inorganic adhesive.
• These include soldering and brazing. These
  adhesives are unlike welding because they do not
  melt the base material.
• They use a melted metal alloy as a bonding agent.
• Soldering uses a tin-lead base alloy.
• Brazing is similar to soldering but uses a base
  of copper, brass and bronze, silver alloy , or
  aluminum alloy.
• Both solder and brazing use capillary attraction
  to draw the braze metal into the joint.

10
Bibliography

• Wright, R. T. (1999). Processes of manufacturing
  pp. 358-370 Tinley Park, IL Goodheart-Wilcox.