polymers and polymer composites

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