Bulletproof VestGROUP 5

LOW ZHI MING

WONG WEN JIE DOUGLAS

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Table of Contents• General Overview

• Synthesis of polymer

• Processing of Polymer

• Manufacturing of Product

• Summary

• References

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General Overview

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General OverviewWhat constitutes a bulletproof vest?

• Absorbs impact from fire-arm projectiles

• Prevents projectiles and fragments from penetrating through

• Light weight but tough

• Utilizes layers of strong fiber (Kevlar)

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How does it work?• Bullet caught in a web of strong fibers

• Fibers absorb and disperse the impact

• Bullet is deformed

• Additional energy absorbed by each successive layer

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What is Kevlar?• A registered trademark for a para-aramid synthetic fiber

• Poly(p-phenylene terephthalamide), PPTA

• Belong to the group of polyamides

• Different grades of Kevlar

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Properties of KevlarAdvantages

• High tensile to weight strength

• High structural rigidity

• High heat resistance

• Resistance to low temperature

• High chemical resistance

• Low electrical conductivity

• Insoluble in water

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Disadvantage

• Suffer from ultra violet light degradation

Properties of Kevlar

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Synthesis of Polymer

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Synthesis of Polymer

+

n

+ (2n-1) HCl

para-phenylenediamine terephthaloyl chloride poly(p-phenylene terephthalamide)

• Step polymerization, condensation reaction

• Solvent used: N-methyl-pyrrolidone and calcium chloride

• Occurs under anhydrous conditions, between -15o C and 30o C

nn

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Processing of Polymer

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Processing of Polymer• Dry jet-wet spinning

• Polymer in concentrated sulfuric acid solution(~20% polymer)

• Extrusion and quenching

• Proceed in the bath while undergoing stretch

• Withdrawn from bath and wound up

• Subsequent washing step to remove residue acid solvent

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Manufacturing of Bulletproof Vest

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Manufacturing of Product• Making of panel cloth

• Twisting fibres into yarns

• Weaving in a simple pattern

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Manufacturing of Product• Cutting of the panels

• Fabric is first unrolled onto a cutting table that must be long

• As many layers as required are laid out on table

• Cut sheets placed on layers of cloth

• Cutting wheel tool

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Manufacturing of Product• Sewing of the ballistic panels

• Worker places stencil on top of layers

• Rubs chalk on exposed areas of panel

• Sewer stitches layers together

• Size label

• Finishing the vest

• Shells for panels sewn together in same factory

• Panels slipped into shells

• Accessories sewn on

• Boxed up and shipped to the customer

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Applications• Bodywork of F1 racing cars

• Walking boots

• Canoe

• Military helmet

• Backplate of Motorola smartphone

• Ropes & cables

• Tactical vests

• Bow of violin

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Summary

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Summary

• Poly (p-phenylene terephthalamide) is made by step polymerization

• Dry jet-wet spinning is used for processing of Kevlar

• Manufacturing steps include fabric roll production, cutting into panels, sewing up stacked panels and completion of whole vest

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Referenceshttp://compositeswiki.org/kevlar/

http://www2.dupont.com/Personal_Protection/en_GB/assets/PDF/Kevlar%C2%AE%20Technical%20Guide.pdf

http://www.madehow.com/Volume-1/Bulletproof-Vest.html

http://books.google.com.sg/books?id=AYjFoLCNHYUC&pg=PA482&lpg=PA482&dq=wet+spinning+kevlar+process&source=bl&ots=GP0uQw7rDA&sig=xcphLUe9v2OX7BlCZ1jD-xD9BJg&hl=en&sa=X&ei=by8PU-qOLauRigebs4CwCQ&ved=0CCcQ6AEwAA#v=onepage&q=wet%20spinning%20kevlar%20process&f=false

http://textilesupdate.com/french-machinery-at-techtextil-frankfurt

http://www.youtube.com/watch?v=eRabvfq8TdA

http://www.youtube.com/watch?v=S_jXAddQDnM

http://www.youtube.com/watch?v=6vSaw1esxLY

http://www.youtube.com/watch?v=CDfehw6LIR0

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End

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