By –Bala Vignesh.v
Prakash.D
 Any substance that is capable of
holding materials together in a
functional manner by surface
attachment that resists separation is
called adhesive.
 The two materials which are to be
joined are called “ADHEREND”.
It should make a strong bond between two adherends.
It should be able to spread over the surfaces of adherends.
It should not be affected by air ,heat or moisture.
It should resist chemicals, acids and bases.
High peel and impact strength , combined with excellent shear strength. Good
environmental resistance and elevated-temperature properties (upto 177 Celsius).
CLASSIFICATIONS
OF ADHESIVE
1.Based on composition of principal
components.
2.Based on mechanism of adhesion.
Natural materials.
starch
glue.
1.vegetable
2.animal
3.casein
4.blood albumin
Synthetic materials
1.phenolformaldehyde
2.epoxy
3.melamine
 Starch adhesives are a type of eco-friendly adhesive made from natural starches,
which are derived from plants such as corn, wheat, and cassava.
 Biodegradable
 Non-toxic
 renewable.
A type of eco-friendly adhesive derived from plant-based starches
 A type of adhesive made from the milk protein casein, extracted from
skimmed milk.
 Blood albumin glue, also known as blood cement or blood adhesive, is a type of
adhesive made from serum albumen, a protein component of blood
 Phenol formaldehyde resins (PF) are a class of synthetic polymers produced by the
reaction of phenol (an alcohol derived from benzine) with formaldehyde (derived
from methane.)
 This glue is the most commonly used glue in WATERPROOF contruction panels,
beams and including many of the marine plywoods.
 Melamine adhesive is primarily composed of melamine resin, a thermosetting
plastic material derived from melamine and formaldehyde.
 is a specialized type of adhesive designed for bonding wood, particleboard,ETC.
BASED ON
MECHANISM OF
ADHESION
1.
Chemically reactive
2.
Pressure sensitive
3.
Solvent responsive
4.
Heat sealing
Chemically reactive adhesives are typically characterized by the formation of permanent bonds
between substrates, providing resistance to chemicals, moisture, and heat.
PRESSURE SNSITIVE:
Pressure sensitive adhesives (PSAs) are a type of non-reactive adhesive that forms a bond
when pressure is applied to bond the adhesive with a surface
HEAT SEALING:
A type of adhesive designed to bond two substrates together when exposed to heat
and pressure.
Also known as heat seal coatings or thermoplastic adhesives.
 Absorption – a thin film bonds two materials on a molecular
level. This is also known as electrostatic adhesion.
 Mechanical adhesion – bonds which occur between porous
or uneven surfaces
 Chemical bonding – the strongest and most durable bonds,
where the adhesive molecules react with the surface and
molecules and fuse them together.
Adhesives are made of molecules that can attract other groups of atoms,
similar to static electricity. When glue is applied to a surface, the adhesive
molecules enter the surface's pores and spaces, bonding with the surface
molecules. As the glue dries, it hardens, causing the molecules to stick
together.
 Physical factors:
Surface tension
FACTORS
AFFECTING
ADHESIVE ACTIONS
Porosity of surface
Thickness of adhesive film
Shelf life
 Chemical factors
Degree of polymerization
Ph of medium
1
The bonding is free
from any residual
stresses , high heat.
2
3
4
By using adhesives,
Galvanic corrosion of
dissimilar joints is
minimized by
preventing direct metal
to metal contact.
They can be applied to
the surface of any
material,such as glass
and metal,metal and
metal,plastic and metal
, etc.
Surfaces are easily and
quickly attached by
adhesives.
The bond strength of adhesive mayerials decrease rapidly with rise in
temperature and by and large they are organic materials so they cannot be used
at high temperatures.
Adhesives are susceptible to high humidity.
For reliable strength by use of adhesives only plain and clean surface is
necessary.
Adhesive strength is usually lower than joining methods like welding and
riveting.
For bonding of loud speakers
Coat and seal electrical connections and battery
terminals against corrosion.
Casting of electronic parts inside a safety sensor
PCB(printed circuit board) makes use of
adhesives to mount devices , and to improve
circuit board perfomance.
 Adhesives are ideal for aircraft as they
reduce the need for mechanical
fastner(which add to the aircraft weight)
and allow greater freedom of substrate
material choice.
 Thread locking: anaerobic adhesives are
used for thread locking , which prevents
vibration loosening.
 Structural bonding :adhesives are used to
bond components and fill air gaps in
aircraft.
 Weight Reduction: Adhesives can replace mechanical fasteners, reducing vehicle
weight and improving fuel efficiency.
 Improved Safety: Adhesives can absorb impacts, reducing the risk of injury and
damage to passengers and vehicles.
 Increased Efficiency: Adhesives can improve the thermal management of batteries
and electrical components, extending their lifespan and improving overall vehicle
performance.
 Reduced Maintenance: Adhesives can provide a durable and long-lasting bond,
reducing the need for repairs and maintenance
1.Mechanical engineering :
Mechanical applications are welding, screwing and riveting.
Recently , adhesive bonding has become more widely used in this area
Marine engineering :
Moisture resistance of adhesives is helpful For marine environments
Durablity of adhesives in wet conditions is extremely good.