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Rubber
 

Rubber

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    Rubber Rubber Presentation Transcript

    • ELASTOMERS & FIBERS
      11.03.2010
    • Elastomers
      A special class of linear polymers that display an exceptionally large amount of elastic deformation when a force is applied.
      low Young's modulus.
      Elastomers are amorphous polymers existing above their glass transition temperature , so that considerable segmental motion is possible.
    • Elastomers
      Elastomers are usually thermosets but may also be thermoplastic.
      The long polymer chains cross-link during curing, i.e., vulcanizing.
      Vulcanization is a chemical process for converting rubber or related polymers into more durable materials.
      These additives modify the polymer by forming cross-links (bridges) between individual polymer chains
    • Thermoplastic elastomers (TPE), sometimes referred to as thermoplastic rubbers, are a class of copolymers or a physical mix of polymers (usually a plastic and a rubber) which consist of materials with both thermoplastic and elastomeric properties.
    • Advantages
      TPE materials have the potential to be recyclable since they can be molded, extruded and reused like plastics, but they have typical elastic properties of rubbers which are not recyclable owing to their thermosetting characteristics.
    • Disadvantages
      relatively high cost
      poor chemical and heat resistance
      low thermal stability.
    • Rubber products used for their flexibility, good electrical insulation, low internal friction, & chemical resistance.
      Additives, accelerators, stiffeners, antioxidants.
      Artificial elastomers
    • Fibers
      Fibers represent a very important application of polymeric materials, including many examples from the categories of plastics and elastomers.
      Man-made fibers include materials such as nylon (a generic term for polyamides) , polyester, rayon, and acrylic.
    • Fibers
      combination of strength, weight, and durability.
      fibers are at least 100 times longer than they are wide. Typical natural and artificial fibers can have axial ratios (ratio of length to diameter) of 3000 or more.
    • Nylon
      synthetic fiber, known for its strength, elasticity, toughness, and resistance to abrasion, has commercial applications including clothing and carpeting.
      Nylon has a large electrical resistance.
    • bullet-proof vests
      layers of very strong fiber to "catch" and deform a bullet.
      A bulletproof vest consists of a panel, a vest-shaped sheet of advanced plastics polymers that is composed of many layers of Kevlar
      The layers of woven Kevlar are sewn together using Kevlar thread
    • bullet-proof vests
      It is placed inside of a fabric shell that is usually made from a polyester/cotton blend or nylon for comfort while wearing.
      A bulletproof vest may also have nylon padding for extra protection.
      built-in pouches are provided to hold plates made from either metal or ceramic bonded to fiberglass
    • bullet-proof vests
      fiber and yarn tensile strength
      fabric weavers test the tensile strength of the resultant cloth
      Though the bullet will leave a dent, it should be no deeper than 1.7 inches (4.4 centimeters).
    • Kevlar
      Kevlar, trademark for poly-para-phenyleneterephthalamide, a liquid polymer that can be spun into aramid fiber and woven into cloth. Originally, Kevlar was developed for use in tires, and later for such diverse products as ropes, and various parts for planes and boats.
    • Kevlar
      high strength material.
      Kevlar has many applications, ranging from bicycle tires and racing sails to body armor because of its high tensile strength-to-weight ratio—famously: "...5 times stronger than steel on an equal weight basis..."