This presentation contains the synthesis, properties and applications of synthetic Resins like Phenol Formaldehyde,Urea Formaldehyde and Melamine formaldehyde.

2. What is a Thermoset?
• Thermoset materials are those materials that are made
by polymers joined together by chemical bonds,
acquiring a highly cross linked polymer structure.
• The highly cross linked structure produced by chemical
bonds in thermoset materials, is directly responsible for
the high mechanical and physical strength (high strength
to support high stress or load, temperature ...) compared
with thermoplastics or elastomers materials.

3. • On the other hand is this highly cross linked structure
which provides a poor elasticity or elongation of this
materials.

4. • One of characteristic parameter of thermosets materials
are the gel point, which refers to the time when the
material changes from an irreversible way-viscous liquid
state to a solid state during the curing process. Once has
been transferred the gel point the material stops flowing
and it can not be moulded or processed .
• One of the negative aspects of thermosets is its no ability
to recycle, because once they are cross linked or cured it
is impossible to return to a liquid phase material.

5. • They can not melt.
• Generally do not swell in the presence of certain solvents.
• They are insoluble in most of the solvents.
• High resistance to creep.
• Examples and applications of thermoset plastic materials:
• Epoxy resins - used as coating materials, caulks, manufacture of insulating materials, etc ...
• Phenolic resins - tool handles, billiard balls, sprockets, insulation, etc ...
• Unsaturated polyester resins - manufacture of plastics reinforced fibreglass commonly known
as polyester, fillers, etc ..

6. • Synthetic resins are materials with a property of interest
that is similar to natural plant resins: they are viscous
liquids that are capable of hardening permanently.
• Chemically they are very different from the various
resinous compounds secreted by plants.
• Synthetic resins comprise a large class of synthetic
products that have some of the physical properties of
natural resins but are different chemically.
• Synthetic resins are not clearly differentiated from plastics.

8. • UF is an “amino resin” or “amine-formaldehyde” class of
thermoset adhesive.
• They have good Binding property.
• Good adhesion, high curing rate and low cost.
• Brittleness.
• Urea and Formaldehyde are usually in different mole ratios.
Repeating unit of UF

10. • Density: 1500 Kg/m3.
• Tensile strength: 48-78 MNm-2 .
• Compressive strength: 70-110 MNm-2 .
• Better electrical properties.
• Scratch free.
• Get affected by sunlight.

11. These are the uses of UF:
Glues for plywood.
Cellulose and foam products.
Paints..
Surface coatings.
Adhesives.
Plugs, switches, buttons etc.

12. • Urea-formaldehyde is pervasive. Examples include decorative laminates,
textiles, paper, foundry sand moulds, wrinkle resistant fabrics, cotton
blends, rayon, corduroy, etc.
• It is also used to glue wood together.
• Urea formaldehyde was commonly used when producing electrical
appliances casing.
• Urea formaldehyde is also used in agriculture as a controlled release source of
nitrogen fertilizer. Urea formaldehyde’s rate of decomposition into
CO2 and NH3 is determined by the action of microbes found naturally in most
soils. The activity of these microbes, and, therefore, the rate of nitrogen
release, is temperature dependent. The optimum temperature for microbe
activity is approximately 70-90 °F (approx 20-30 °C).

15. •The First phenolic resins were produced by poly condensation
of phenol with aldehyde in 1860.
•In 1860 ‘VON BAYER’ First reported the reaction between
phenol and aldehyde.
•The phenol resin condensation was used industrially in 1902 by
‘BLUMMER’ for production of Novolacs.

16. Phenol-formaldehyde (PF) resins are formed by the
polycondensation between phenol and formaldehyde.
The polycondensation reaction can be catalyzed either by acids
or bases. The acid- catalysed reaction proceeds as follows:
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18. Similarly, the alkali-catalyzed reaction can be represented as follows:
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19. In both the cases further condensation between methylol phenols
and phenols occurs to give the methylene compounds:
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20. If excess of formaldehyde is taken and the reaction
allowed to continue to almost all the available ortho -
and para -positions of phenol molecules, a cross-linked
three-dimensional polymer will ultimately result:
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21. Low stage of polymerization, leading only to linear molecules
phenol is reacted with 75% of the stoichiometric quantity of
formaldehyde using an acid catalyst .In this case, an insufficient
quantity of the formaldehyde , only linear molecules are formed :
The resin formed can be stored for any length of time without
hardening , and further cross-linking, whenever necessary, can
be effected by: adding excess of formaldehyde and then heating.
These types of PF resins are called ‘Novolac' resins or 'BakeIite'
resins.
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23. • The phenolic resin’s polarisability is 10-24cm3 and Enthalpy
of vaporization is 43.52 kJ/mol.
• It’s polar surface area is 9.23 Å2 .
• It has 1 H bond donor and 1 H bond acceptor.
• 72.5 °C is it‘s flash point,
• 181.8 °C at 760 mmHg it’s boiling point and 0.614 mmHg at
25°C is it’s vapour pressure.
• It has Wide variation depending on fillers and nature of resin.
• It is Smooth and has lustrous surface.
• Usually it seems hard and rigid, with good dimensional
stability.
• It may be brittle in thin sections with low impact strength.

24.  Phenolic resins are mainly used in the circuit
board production that is for making circuit board
like PCB ….etc.

25.  Radio cabinet

26.  Engine ignition equipment

27.  Camera

28.  Aerospace application
FIBRE REINFORCED
PLASTICS

30. • Melamine formaldehyde or melamine resin (short Melamine
or MF) is a hard, very durable, and versatile thermosetting
plastic (aminoplast) with good fire and heat resistance.
• It is made from melamine and formaldehyde by condensation
of the two monomers.
• Its good fire retardant properties are due to the release of
nitrogen gas when burned or charred.

31. • MF resins are quite similar to urea-formaldehyde (UF)
resins and are fully compatible with them and, therefore,
are often co-reacted with them to reduce formaldehyde
emissions from particle boards and to prevent degradation
of glue bonds caused by hydrolytic degradation of the UF
polymers.
• The resin blend is called melamine–urea–formaldehyde
(MUF).
• Compared to natural woods or wood veneers, melamine
composite boards and overlay materials have improved
heat, moisture, scratch, and chemicals resistance.

32. • Melamine formaldehyde resins are primarily made up of melamine and
formaldehyde with formaldehyde acting as the cross linker. The melamine
reacts with formaldehyde under slightly alkaline conditions to form
mixtures of various methylolmelamines:

33. • Further heating causes condensation of the
methylolmelamines:

34. Melamine and formaldehyde can also react to give
methylol derivatives of melamine as shown :
•The poly-condensation of methylol melamine derivatives with
larger quantities of melamine will give a linear polymer.
• This polymer when reacted further with additional quantities
of formaldehyde, will give a three-dimensional network as
shown which is found to be insoluble in many solvents.
methylol melaminemelamine
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36. • Melamine resins are used for the manufacture of many
products, including kitchenware, laminates, overlay
materials, particle boards, and floor tiles.
• Melamine is also used in the manufacture of flame-
resistant materials.
• These include textiles such as upholstery, firemen
uniforms, thermal liners, and heat resistant gloves and
aprons.
• Melamine and its salts are also used as fire-retardant
additives in paints, plastics, and paper.

37. • Sulfonated melamine formaldehyde (SMF) is used as a
super-plasticizer for making high-resistance concrete.
• It is mainly used to reduce the water content in concrete
while increasing the fluidity and the workability of it
during handling and pouring.
• The result is a concrete with a lower porosity and a
higher mechanical strength, which exhibits an improved
resistance to aggressive environments and has, therefore,
a longer lifetime.
• One of the most important applications of melamine is the
fabrication of particleboards.

39. amino resins phenolic resins
color colorless colorful
tensile strength Better less
Hardness Better Less
Heat resistance Lower Higher
Moisture resistance lower Higher
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