Polyurethane is a polymer made from organic compounds called isocyanates and polyols. It has many applications due to its versatile properties including flexibility, durability, impact resistance and insulation. Common uses include rigid and flexible foams for insulation and furniture, coatings, adhesives, elastomers and binders. Additives are used to modify properties and include flame retardants, colorants, and bacteriostats. Major applications sectors include construction, automotive, appliances, footwear and renewable energy like wind turbine blades.
2. • Introduction .
• Preparation .
• The properties .
• The types.
• Additives.
• The applications.
3. INTRODUCTION
• Polyurethane, any of a class of synthetic resinous, fibrous, or
elastomeric are compounds belonging to the family of organic
polymers made by the reaction of diisocyanates (organic
compounds containing two functional groups of structure
−NCO) with other difunctional compounds such as hydroxyl.
• Otto Baer and his colleagues in Germany first manufactured
polyurethane in 1937.
4. INTRODUCTION
• The one of polyurethane disadvantages it is a flammable solid
material and when we burn it by fire it will produce high
quantities of ( CO, hydrocyanidein ,in addition to nitrogen's
oxides, isocyanates , and other toxic products).
• It Consists of linked organ units with urethane radical . This
polymer is has a very wide using especially in industries
everything surrounding us which has an insulation, corrosion
&( cooled , heat) resistance properties is almost consists of
polyurethane.
5. PREPARATION
• Polyurethanes are made by the exothermic reactions between
alcohols with two or more reactive hydroxyl (-OH) groups per
molecule (diols, triols, polyols) and isocyanates that have more
than one reactive isocyanate group (-NCO) per molecule
(diisocyanates, polyisocyanates). For example a diisocyanate
reacts with a diol:
6. PREPARATION
Materials used :
• Polyol: it is a viscosus liquid susbstance of light yellow
color.
• MDI : the texture of the texture is dark yellow.
• Water.
• Triethylamine.
7.
8. PREPARATION
• Rigid foams are made with PMDI and polyether glycols, along with
low-molecular-weight dialcohols to increase the rigidity. Use of
PMDI, which contains a larger number of reactive functional
groups, results in a network polyurethane. A blowing agent such as
pentane is normally added to augment the foaming.
(Chlorofluorocarbons such as Freon [trademark] used to be
employed as blowing agents before they were declared
unacceptable for depleting ozone in the stratosphere.)
9. THE PROPERTIES
• Wide Range of Hardness :The classification of hardness for
polyurethane relies on the prepolymer's molecular structure
• High Load Bearing Capacity :Polyurethane has a high load
capacity in both tension and compression. Polyurethane may
undergo a change in shape under a heavy load, but will return to
its original shape once the load is removed with little
compression set in the material when designed properly for a
given application.
• Abrasion & Impact Resistance:For applications where severe
wear prove challenging, polyurethanes are an ideal solution even
at low temperatures.
10. THE PROPERTIES
• Flexibility : Polyurethanes perform very well when used in high flex
fatigue applications. Flexural properties can be isolated allowing
for very good elongation and recovery properties.
• Strong Bonding Properties: Polyurethane bonds to a wide range of
materials during the manufacturing process. These materials
include other plastics, metals, and wood. This property makes
polyurethane an ideal material for wheels, rollers, and inserts.
11. THE PROPERTIES
• Performance in Harsh Environments: Polyurethane is very
resistant to temperature extremes, meaning harsh
environmental conditions and many chemicals will not cause
material degradation.
• Color Ranges: Varying color pigments can be added to
polyurethane in the manufacturing process. Ultraviolet
shielding can be incorporated into the pigment to provide
better color stability in outdoor applications.
• Electrical Properties :Polyurethanes exhibit good electrical
insulating properties.
12. THE TYPES
• Rigid polyurethane foams: Rigid polyurethane foams represent
one of the most commonly known versatile and energy saving
insulation materials , these foams can significantly reduce
energy costs on the one hand and can make commercial and
residential appliances more comfortable and efficient on the
other hand
• Flexible polyurethane foams : comprise some block copolymers
whose flexibility is based on phase separation between the soft
and hard segments, thus pu. Foams may be modified through
deliberate control of the individual compositional ratios of these
segments
13. THE TYPES
• Polyurethane ionomers: the presence of ionic groups in the
polyurethane backbone chain has many advantages , such as
better dispersion in polar solvents due to their enhanced
hydrophobicity and improved thermal and chemical properties .
• Coatings , adhesives ,sealants and elastomers: there is growing
range of applications and advantageous markets that maybe
derived from the use of pus as coatings ,adhesives , sealants
or elastomers ,this is because pus of ten reveals excellent and
versatile mechanical , chemical and physical properties
• Binders: polyurethane binders are often used to bond different
types of fiber and other materials to each other , binders made
from polyurethane help to provide a permanent gluing effect
between organic materials and long strand lumbers , medium
density fiber board , particle board and straw board
14. THE TYPES
• Waterborne polyurethane dispersion: coating and adhesive
that make use of water primarily as the solvent are often
referred to as waterborne polyurethane, there are several
pieces of legislation that place restrictions on the amount of
allowed volatile organic solvents and other hazardous air
pollutions that maybe release into the environment.
• Thermoplastic polyurethane: reveal vast combination of both
physical properties and processing applications , Usually
they’re flexible and elastic with good resistance to impact,
abrasion and water, there is the possibility for coloring as well
fabrication using a wide range of techniques
15. ADDITIVESColornats:
• Many flexible foam products are color coded during manufacture to
- To identify product grade
- To conceal yellowing,
- To make an appealing consumer product
• The historical method of coloring foam was to blend in traditional
pigments or dyes.
• Typical inorganic coloring agents included titanium dioxide, iron
oxides and chromium oxide.
• Organic pigments originated from the azo/diazo dyes,
phthalocyanines and dioxazines, as well as carbon black .
• Typical problems encountered with these colorants included high
viscosity, foam instability, migrating color and a limited range of
available colors .
16. ADDITIVES
Flame retardants :
• Low-density, open-celled flexible polyurethane foams have a large
surface area and high permeability to air and thus will burn given
the application of sufficient ignition source and oxygen .
• Flame retardants are often added to reduce this flammability.
• The choice of flame retardant for any specific foam often depends
upon the intended service application of that foam and the
attendant flammability testing scenario governing that application
• The most widely used flame retardants are the chlorinated
phosphate esters, chlorinated paraffins and melamine powders
have also been used.
17. ADDITIVESAntistatic Agents:
•
Some flexible foams are used in packaging, clothing and other
applications where it is desired to minimize the electrical
resistance of the foam so that buildup of static electrical charges is
minimized. This has traditionally been accomplished through the
addition of ionizable metal salts, carboxylic acid salts, phosphate
esters and mixtures thereof.
• These agents function either by being inherently conductive or by
absorbing moisture from the air.
• The desired net result is orders of magnitude reduction in foam
surface resistivity.
18. ADDITIVES
• Bacteriostats:
• Under certain conditions of warmth and high humidity,
polyurethane foams are susceptible to attack by
microorganisms.When that is a concern, additives against
bacteria, yeast or fungi are added to the foam during
manufacture.
19. THE APPLICATIONS
• Polyurethane is one of most widely polymers which it is
used in industries and many applications.
• It is achieve this publicity because it ease to dealing with it
& manipulating its properties.
• We use it in coating,insulation,different types of foams
,textiles , foot wears , and many other applications and they
used it in different percentage as in following
table(according to USA usage):
20.
21. THE APPLICATIONS
• in renewable energy sector (PU) is ideal for manufacturing wind
turbine rotor blades. It offers advantages over other plastic
systems such as epoxy and unsaturated polyester resins in
terms of process, cost efficiency and mechanical properties.
22. THE APPLICATIONS
• one of most unique application is oleo sponge: it is
a technology for recovering oil and other petroleum
products from bodies of water .
23. THE APPLICATIONS
• MDF WOOD : IS A type of wood which use specially in furniture due
to the unique properties of its such as :
• Excellent mechanical strength properties
Emission-free gluing
Outstanding long-term stability under permanent load
• In the past they were blend sawdust & other additives with urea
resins but with the time they noted that it’s released toxic
formaldehyde so they replace it with polyurethane which has
greater stability than urea and gives MDF more properties .
• It has this widely usage because of its physical & chemicals
properties and it’s easy to paint with many different colors than
normal wood and also it has less pores than wood as shown in fig.
