2. Composite Materials
Classification of composites
Polymer & Polymer matrix composite
Classification of Polymers
Fibers in PMCs
Applications Of PMCs
Limitations of PMC
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Contents:
3. Composite Materials
Made from two or more
constituent materials
Materials having
significantly different
physical or chemical
properties.
Produced material have
different characteristics
from the individual
components.
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5. Polymer & Polymer matrix composite
• Polymer :
A large molecule (macromolecule) composed of
repeating structural units (monomer) typically
connected by covalent chemical bonds.
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6. Polymer & Polymer matrix composite
• Polymer Matrix Composite (PMC):
Consisting of a polymer (resin) matrix and fiber.
Very popular due to their low cost and simple fabrication
methods.
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8. 8
Thermosetting and Thermoplastics Polymers
Thermosetting
Polymers
Extensive crosslinking
formed by covalent bonds.
High Thermal stability.
High dimensional
stability.
Low weight.
High rigidity.
Can not be recycled due
to its heavy covalent bonds.
Thermoplastics
No chemical linking between
individual molecules.
Molecules are bonded by weak
secondary bonds like Van der walls
bonds and hydrogen.
Parts can be made and joined by
heating.
Can be remolded, and recycled.
B e tter toughness and impact
resistance than thermosets.
9. Fibers in PMCs:
Various forms:
Discontinuous (chopped)
Continuous or woven as a fabric
Fibers used
• Principal fiber materials in FRPs are glass, carbon, and Kevlar 49.
• Less common fibers include boron, SiC, Al2O3 and steel.
• Glass (in particular E-glass) is the most common fiber material in today's
FRPs; its use to reinforce plastics dates from around 1920.
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10. Resin Transfer Molding
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In the RTM process, dry reinforcement is pre-shaped and oriented into
skeleton of the actual part known as the preform which is inserted into a
heated matched die mold .
The heated mold is closed and the liquid resin is injected.
The part is cured in mold.
Finally mold is opened and part is removed from mold.
11. Advantages
Large complex shapes and curvatures can be made easily.
High level of automation.
Simpler than in manual operations.
Takes less time to produce.
Low volatile emission
Cost effective.
Low skill labor required
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Resin Transfer Molding
12. Disadvantages
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• Mold design is complex.
• Requires Mold-filling Analysis.
• Fiber reinforcement may Move during resin transfer.
Resin Transfer Molding
14. Manufacturing Process of thermoplastics
polymers:
Injection Molding
• Closed Mold process
• Polymer is Mixed with very
short reinforcing fibers
(10- 40%)
• Polymer-fiber mixture in
form of pellets is fed
through a hopper.
• The material is then
conveyed forward by a
feeding screw and forced
into a split mold, filling its
cavity through a feeding
system with sprue gate
and runners.
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15. Injection Molding (CONT.)
• Reciprocating screw since it
not only rotates but also
moves forward and backward
according to the steps of the
molding cycle.
• It acts as a ram in the filling
step.
• then retracts backward in the
molding step.
• Heating elements, placed over
the barrel, soften and melt the
polymer.
• The mold is equipped with a
cooling system providing
controlled cooling and
solidification of the material.
Cooling
channel
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19. APPLICATIONS OF PMCs
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Aerospace and Military Aircraft
The aerospace industry is estimated to consume about 50
percent of advanced composites production in the United
States.
The primary matrix materials used in aerospace applications
are epoxies, and the most common reinforcements are
carbon/graphite, aramid (e.g. Kevlar), and high-stiffness glass
fibers.
Compared with metals, the principal advantages of advanced
composites in aerospace applications are their superior
specific strength and stiffness, resulting in weight savings of
10 to 60 percent over metal designs.
21. Automotive Industry
The principal motivation for introducing PMCs is cost savings
Because the industry is mature and highly competitive.
Because of greatly improved corrosion resistance PMC
automobiles could last 20 or more years compared to the current
average vehicle lifetime.
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APPLICATIONS OF PMCs
23. .
APPLICATIONS OF PMCs
Construction
A potentially high-volume market for PMCs lies in construction
applications especially in.. Construction of
Buildings
Bridges
Housing
Lampposts
Smokestacks
Highway culverts
The smith road bridge all-composites
bridge, Ohio, USA
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24. Medical Devices
The impact of PMCs on orthopedic devices such as
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Hips
Knees
bone plates,
intramedullary nails is expected to be especially
significant.
APPLICATIONS OF PMCs
25. Advantages of PMC
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Good inplane stiffness and strength.
Low density.
Relatively low cost.
Corrosion resistance.
Low coefficient of thermal expansion.
Relatively mature technology.
Excellent in-service experience.
26. Limitations of PMC
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Low maximum working temperature.
Sensitivity to radiation and moisture.
Processing temperature are generally higher than
those with thermosets.
Required special processing equipment.
Thermoset resins have poor impact resistance.
27. Conclusion
In 21st century we are in need of light but stronger
materials. From automobile to aerospace, medical ,
military technology and even in household we need
heavy duty, corrosion resistant material. Here comes the
composites with all those specifications. And day by day
the field of composite materials is getting stronger.
Among all the composites Polymer Matrix Composites
(PMC) have a strong place due to its specialization.
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