2. DEFINITION
ADHESIVES
1. A material used for holding two surfaces
together. It must wet the surfaces, adhere to
the surfaces, develop strength after it has been
applied, and remain stable.
2. It is made from inorganic mineral sources, or
biological sources
3. Adhesive bonding provides flexibility in design
and in the use of different materials
4. a mixture in a liquid or semi-liquid state that
bonds items together.
3.
4. HISTORY
4000 B.C
The first evidence of a substance being used as
an adhesive
Archaeologists studying burial sites of
prehistoric
tribes found foodstuffs buried with the
deceased in broken pottery vessels
that had been repaired with sticky resins from
tree sap.
5. HISTORY
Archaeologists have also uncovered statues from
Babylonian temples that have ivory
eyeballs glued into eye sockets. This tar-like glue
has held for almost
6,000 years.
The period of time between 1500-1000 B.C. gave
further proof that
glue had become a method of assembly. Paintings
and murals showed
details of wood gluing operations. A casket
removed from the tomb of
King Tut shows the use of glue in its construction.
6. HISTORY
The next period of activity is from 1-500 A.D. when the
Romans and Greeks developed the art of veneering and
marquetry, which is the bonding of thin sections or layers
of wood.
7. HISTORY
The next period of activity is from 1-500 A.D. when the
Romans and Greeks developed the art of veneering and
marquetry, which is the bonding of thin sections or layers
of wood.
The industrial revolution caused an
explosion in technical breakthroughs that resulted in new
materials becoming available for use in formulating
adhesives.
8. TYPES OF ADHESIVES
ANIMAL GLUES
are made from the
protein extracted from the bones, hide,
hoofs, and horns of animals by boiling. The
extract is cooked to form a gelatin material.
The gelatin can the be re-liquified with heat,
which gives it quick setting properties. Its
major use has been in the wood and
furniture industry.
9. TYPES OF ADHESIVES
ON BASIS OF CURING METHOD:
A. Non reactive adhesives
1. Drying adhesives
2. Hot Melt Adhesives
3. Pressure sensitive adhesives
B. Reactive adhesives
1. UV light curing adhesives
2. Heat curing adhesives
3. Moisture curing adhesives
10. Solvent based adhesives
are a mixture of ingredients (typically
polymers) dissolved in a Solutions. Solutions
are acrylic polymers in petroleum based
solvents. Solvent Based adhesives are divided
into:
Wet Bonding adhesives are those where
substrates are joined while adhesive is still wet
and then allowed to evaporate.
Contact Adhesives in which both substrates
are coated with adhesive which is allowed to
evaporate before the bond is made and the
bond is formed by bringing the two coated
substrates together.
11. Water based adhesives
These are adhesives that use water as a carrier
or diluting medium, and set by allowing the
water to evaporate or be absorbed by the
substrate.
One of the major advantages of water based
(or waterborne) adhesives is the absence of
volatile organic compounds (VOCs).
Water Based adhesives are divided into
wet bonding adhesives and contact adhesives
same as defined in solvent based adhesives.
12. Hot Melt Adhesives
also known as hot glue is commonly supplied
in solid cylindrical sticks of various diameters,
designed to be melted in an electric hot glue
gun.
Pressure Sensitive
Adhesive (PSA)
adhesives that form a bond with the substrate
on application of light pressure. PSA can be of
water based, solvent based and hot melt.
13. CELLULOSE ADHESIVE
is made from a natural polymer found in trees and woody
plants. It is the adhesive used on the
cellophane wrapper on cigarette packs; it
is the adhesive on decals we put on
windows; and, interestingly enough, the
adhesive used on the strippable wallpaper
we have in our homes that allows us to
remove the paper easily.
ultraviolet curing adhesives
solidify or harden when it exposed to one source of
ultraviolet radiation with an predefined intensity
and wavelength. This process of curing requires less
time as compared to heat cured adhesives
14. FISH GLUE
a similar protein-based
glue made from the skins and bones of fish.
An exceptionally clear adhesive can be
CASEIN GLUE
made from a protein
isolated from milk. The extraction process
creates an adhesive that is waterproof. Its
first use was in bonding the seam of
cigarette paper.
15. STARCH
a carbohydrate extracted
from vegetable plants such as corn, rice,
wheat, potatoes, and is probably better
known as paste. Major use area is in
bonding paper and paper products such
as bookbinding, corrugated boxes, paper
bags, and wallpaper paste
16. CLASSIFICATION OF
ADHESIVES
CHEMICAL REACTIVE
Basically an adhesive of this type is supplied in a low molecular
weight form and after application a polymerisation reaction is
allowed to take place.
polymerisation can be achieved by:
moisture & heat
THERMOPLASTIC
Basically the adhesives in this class are thermoplastic in nature which
means they are heated
to a sufficient temperature where they will flow and wet the
substrates and then set and
develop the bulk strength on cooling.
17. EVAPORATION OR DIFFUSION
In adhesives of this class the adhesive polymers is essentially in its
final form however, wetting of the adherend is achieved by dissolving
or dispersing the polymers in a suitable solvent.
18. USES OF ADHESIVES
Physically interlocks Materials
Physically interlocks and chemically bonds
materials
Dissolves plastics, which then re-harden,
similar to welding
Binds to water and hydroxyl groups on
substrate surface
20. PROPERTIES
PHYSICAL PROPERTIES
Adhesion to a variety of substrates allows bonding of dissimilar
materials if necessary
High damping capacity of the adhesive dissipates dynamic
stresses of vibration, motion, & impact throughout the bond &
peel stresses at the bond line
Flexibility and damping resistance resists thermal expansion
stresses when the coefficients of thermal expansion are
different between adhesive and substrates
21. ENVIRONMENTAL RESISTANCE
Resists end-use or post-processing temperatures to maintain
adhesive chemistry and the physical bond
Withstands physical shock at a range of temperatures
Maintains adhesive performance despite exposure to UV
light, rain, salt water, and other weathering conditions
22. DEFINITION
SEALANTS
A sealant is a viscous material
that changes state to become
solid, once applied, and is used
to prevent the penetration of air,
gas, noise, dust, fire, smoke, or
liquid from one location through
a barrier into another.
23. sealants are used to close small openings that are
difficult to shut with other materials, such as
concrete, and drywall
24. A material that has the necessary adhesive and
cohesive properties to form a seal.
25. Sealants, despite not having great strength, convey a
number of properties. They seal top structures to the
substrate, and are particularly effective in
waterproofing processes by keeping moisture out (or
in) the components in which they are used.
26. They can provide thermal and acoustical insulation,
and may serve as fire barriers.
27. HISTORY
Sealants were first used in prehistory in the broadest
sense as mud, grass and reeds to seal dwellings from the
weather.
In the 17th century glazing putty was first used to seal
window glass made with linseed oil and chalk, later
other drying oils were also used to make oil-based putties
which were often referred to as caulks. In the
1920's polymers such as acrylic polymers, butyl polymers
and silicone polymers were first developed and used in
sealants. By the 1960's synthetic-polymer-based sealants
were widely available.
29. TYPES OF SEALANTS
Silicone Sealants
A flexible and waterproof substance normally used as a
sealant for sealing joins around baths, sinks or other
plumbing fixtures.
It can withstand very high temperatures, making it ideal
for applications that suffer high heat exposure
31. Elastic Sealant
A sealant made of a flexible material in
a plastic state during forming or application. A
common elastomeric sealant, polysulfide, is a high-
performance type, made of either
polysulfide polymer or rubber.
35. USES OF SEALANTS
1. Horizontal and vertical metal-to-metal and masonry-to-
masonry expansion and control joints
Floor tile expansion joint over concrete control joint
38. 4. Spandrel glass
- An architectural material
used to cover construction
materials, disguise things
like arches and columns,
and present a finished,
seamless, and sleek exterior
to buildings.
39. 5. Perimeter of doors and
fixed window frames
6. Fixing larger cracks
40. 7. Waterproofing
Expansion joints in Building Facades
Lap Joints – Flashing/Coping
Door/Window/Curtain wall perimeters
Traffic Joints – Vehicular/Pedestrian
Glazing – Structural/Backbedding
41. 8. Acoustical
Interior wall joints
Base and top plate
Thresholds
Exterior wall joints and window
perimeters
9. Firestopping
Wall to Wall Joints
Floor to Floor Joints
Floor to Wall Joints
Head of Wall Joints
Wall Penetrations
44. The main difference between adhesives and sealants is that
sealants typically have lower strength and higher elongation
than adhesives do.
Sealants generally contain inert filler material and are usually
formulated with an elastomer to give the required flexibility
and elongation.
They usually have a paste consistency to allow filling of gaps
between substrates. Low shrinkage after application is often
required.
Many adhesive technologies can be formulated into sealants.
DIFFERENCE BETWEEN SEALANTS AND ADHESIVES
