POLYMERS AND POLYMERS AND POLYMER POLYMER
COMPOSITESCOMPOSITES
Contents• Topics• Introduction on polymers• Definition• Advantages• Disadvantages• Classification• Origin of composites• Classification • Matrices• Reinforcements• Processing• Characterization• Applications • Future trends• Conclusion
Introduction
• Polymers are using for making • Fancy decoration items• Textiles• Building materials or packing materials • Light and elegant luggage made of
Plastics.• Plastic chairs to add colour and comfort.• Armour shield made of Polycarbonate
combines the transparency of glass and strength of steal
What is a polymer?• A long
molecule made up from lots of small molecules called
• monomers.
Elastomers, plastics & fibres
THERMOPlASTICS
Thermosets
Polymers replaced metals, ceramics and
wood. Why?• High strength • Light weight • Good flexibility • Special electrical properties• Resistance to chemicals• Ability for quick and more
production.• Fabrication into complex shapes in
wide variety of colours.
Crystalline polymers
Glass transion temperature
Are polymers mostly amorphous, crystalline, or in-between? Also, what is the glass transition temperature? the Tg of a Rubber band is below RT the Tg of polystyrene is above RT Glass transition temperature (Tg) Crystalline transition temperature (Tc)Melt Transition (Tm)Decomposition temperature (Td)
Glass transition temperature
Glassblowing at temperatures just above the glass transition
Tacticity-Isotactic
Syndiotactic
Tacticity- atactic
Significance:• Polymers can be used to • Bond objects• Seal joints• Fill cavities• Bear loads• Clothing the naked to powering a space
vehicle to even replacing a human organ.» Artificial heart» Artificial kidney
• Limbs etc
Why composites?• Individual polymers not alone satisfy our
needs. Search for new materials started and composites originated.
• • Composite materials are made of more than
one phase, in order to achieve combined properties that cannot be met by a single-phase material.
• Composites are able to meet diverse design requirements with significant weight savings as w ell as high strength-to- weight ratio
What are composites?
• Composite" is a material having two or more distinct constituents or phases.
• "Polymer composite" is a homogeneous polymer based material created by the synthetic assembly of a polymer and reinforcement to obtain specific properties.
• Natural composites • Eg.Bone, mollusc shells and wood
Origin of composites• Charles Macintosh in the middle of
the nineteenth century• Raincoats are made from two layers
of cotton fabric and embedded them in natural rubber.
• Rubber -waterproof• Cotton layers –comfortable to wear.• Combination of water resistance of
polyisoprene and the comfort of cotton.
First Composite
Advantages over conventional
materials • Tensile strength of composites is four to six time
grater than that of steel or aluminum• 30-45% lighter than aluminum structures
designed to the same functional requirenmts• Composites are versatile than metals• Long life offers excellent fatigue, impact,
environmental resistance and reduced maintenance
• Composites enjoy reduced life cycle cost compared to metals
• Exhibit excellent corrosion resistance and fire retardancy
Classification of composites
• BLENDS- a blend is a mixture of two or more substances.
Eg: steel, which is a combination of iron and carbon.
FIBER COMPOSITES-Composites
• Contain fibers in the matrix material
Fiberglass fish holding tanks
NANOCOMPOSITES • Composites in which the fiber
reinforcement is on the extremely small "nano scale" (1*10-9 meters) are known as nanocomposites
• Clay particles is a common nano-component in composites
Bio composites • Biocomposites
are materials made by nature or synthetically that include some type of natural material in its structure. The amazing thing is that it grows with the fruit
Natural composites• Wood • Cotton • Hemp • Soyabean • Wheat • Corn
What is a fiber reinforced polymer
plastics?• Fiber reinforced composites
(FRP) are composites prepared by the incorporation of fibers into Plastic material
• Combination of polymeric substances with solid fillers give rise to filled composites
FRPS
MATRICES/RESINS/BINDER
•Thermoplastics. • polyolefins, polyamides, vinyl
polymers, polyacetals, polysulphones, polycarbonates, polyphenylenes and polyimides. Acrylonititrile-butadiene-styrene(ABS), Fluropolymers,Nylons,Styrene -acrylonitrile
Thermosets• Unsaturated polyesters • Epoxides, acrylic resins, alkyd resins• Diallyl phthalate (DAP). • Melamine formaldehyde• Phenol resins• Polyurethane
Fibers• A wide range of amorphous and
crystalline materials can be used as the fibre
• Glass fibers –largest used fibers• Carbon fiber • Aramid fibers• Nylon fibers• Natural fibers
What Fibers Do
• Act as a reinforcement• Increase the overall strength
What the Matrix Does
• The matrix holds the fibers together. (binder)
• The matrix can absorb energy by deforming under stress. The matrix adds toughness to the composite.
• Fibers have good tensile strength (that is, they're strong when you pull on them), they usually have awful compressional strength.
• The matrix gives compressional strength to the composite.
Mechanism of Reinforcement
• The reinforcement of a low modulus polymer with a high modulus, high strength fiber uses the plastic flow of the polymeric material under stress to transfer the load to the fibre this results in a high strength, high modulus composite.
:
• Parameters• Strength of the fibers and of
the polymer matrix.
• Elastic modulus of the fibers and of the matrix.
• Aspect ratio of the fibers (L/D)
Applications of FRPs
Compounding-incorporation of additives into the matrix
• Vulcanisers• Accelerators• Activators• Fillers• Colourig agents• Stabilizers• Plasticizers
Moulding-conversion of compounded mix to a desired
shapeCompression moulding
Compression Moulding
Injection moulding
Injection Moulding
INJECTION MOULDING PROCEDURE
Injection Moulding
INJECTION MOULDED COMPONENTS
INJECTION MOULDED COMPONENTS
INJECTION MOULDING MACHINE
Transfer Moulding
TRANSFER MOULDED COMPONENTS
Extrusion Moulding
TUBE EXTRUDED COMPONENTS
Blow moulding
Types of blow moulding
Blow moulded products
FRP Manufacturing• Hand lay –up• Spray lay up• Filament winding process
Hand- lay up
Filament winding
Spray –up Process
Spray-up process
Filament winding process
Filament winding
Pultrusion
Resin Transfer Process
Laminate Process
Laminates-a product obtained by joining two or more
layers of a solid material.• Parallel laminate-
grains of the layers are parallel to each other
• cross laminate-Some layers are right angles to each other
• Adherends-layers of the materials are so bonded by an adhesive
• Plywood-cross laminate
Laminates----• Laminated plastics-impregnating sheets
of paper, wood, fiber with a resin solution• Thermosetting resin• Fiber is passed through a solution of resin
bath• Dried at suitable temp (< curing temp)• Cut into suitable size and piled one over
another• Cured in a hydraulic press 180OC,
120kg/cm2
Laminates---• Laminated glass-joining glass
plates/sheets with a layers of plastic in between them
• Safety glass-dry sheet of plastic between two glass sheets
• Thermocole-is a formed plastic –blowing air/plastic through molten PS or Polyurethane
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