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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• Withdrawn from bath and wound up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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