Unit 4
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Questions and Answers

Which of the following is classified as a natural polymer?

  • Low-density polyethylene (LDPE)
  • Cellulose (correct)
  • Polyvinyl chloride (PVC)
  • Polystyrene (PS)

    • What type of polymer is created through addition polymerization?

  • Natural rubber
  • Polystyrene (PS) (correct)
  • Starch
  • Cellulose acetate

    • Which of the following polymers has applications in making flexible pipes and toys?

  • Polypropylene (PP)
  • Polystyrene (PS)
  • Polytetrafluoroethylene (PTFE)
  • Low-density polyethylene (LDPE) (correct)

    • Which polymer is known for its strength and is often used for making bottles and plastic bags?

    <p>High-density polyethylene (HDPE)</p> Signup and view all the answers

    What characteristic distinguishes semi-synthetic polymers from natural and synthetic polymers?

    <p>They are derived from natural sources but chemically modified.</p> Signup and view all the answers

    Which type of polymer is often used for making inner insulation in coaxial cables?

    <p>Polytetrafluoroethylene (PTFE)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of thermosetting plastics?

    <p>They can be remolded</p> Signup and view all the answers

    Which of the following materials is classified as a thermoplastic?

    <p>Polystyrene (PS)</p> Signup and view all the answers

    Which polymer is primarily used in the construction of non-stick surfaces on cookware?

    <p>Polytetrafluoroethylene (PTFE)</p> Signup and view all the answers

    What type of polymer is composed of two or more different monomer subunits?

    <p>Copolymers</p> Signup and view all the answers

    Which additive is primarily used to give color to plastics?

    <p>Pigment</p> Signup and view all the answers

    Which statement about vulcanized rubber is true?

    <p>It cannot be remolded.</p> Signup and view all the answers

    What are petrochemicals primarily derived from?

    <p>Natural gas and oil refinery streams</p> Signup and view all the answers

    Which of these materials is considered a thermoplastic?

    <p>Polyurethane</p> Signup and view all the answers

    What is a primary function of stabilizers in plastics?

    <p>Prevent degradation</p> Signup and view all the answers

    Which of the following statements about thermoplastics is incorrect?

    <p>They have a three-dimensional network structure.</p> Signup and view all the answers

    Which type of polymer is formed through the loss of small molecules during its formation?

    <p>Condensation Polymers</p> Signup and view all the answers

    What distinguishes thermosetting plastics from thermoplastics?

    <p>Thermosets do not soften when heated.</p> Signup and view all the answers

    Which of the following is an example of a natural polymer?

    <p>Wool</p> Signup and view all the answers

    Which factor primarily influences the classification of polymers as fibers?

    <p>Their structure and strength</p> Signup and view all the answers

    What is a key characteristic of elastomers?

    <p>They exhibit exceptional elasticity and resilience.</p> Signup and view all the answers

    Which of the following polymers does NOT fall under the thermoplastic category?

    <p>Bakelite</p> Signup and view all the answers

    How do condensation polymers differ from addition polymers in their structure?

    <p>Condensation polymers may not be exact multiples of monomer units.</p> Signup and view all the answers

    Which of the following is a synthetic polymer used widely in various applications?

    <p>Polypropylene</p> Signup and view all the answers

    Study Notes

    Examples of Common Polymers

    • Low-density polyethylene (LDPE) is used for squeeze bottles, toys, flexible pipes, and insulation covers for electric wires.
    • High-density polyethylene (HDPE) is used for bottles, pipes, inner insulation of coax cable, plastic bags, and other applications.
    • Polypropylene (PP) is used for auto parts, industrial fibers, food containers, bag liners, dishware, and textile/food wrapping.
    • Polystyrene (PS) is used for petri dishes, CD cases, and plastic cutlery.
    • Polytetrafluoroethylene (PTFE) is used for low friction bearings, non-stick pans, inner insulation of coax cables, and coatings against chemical attack.
    • Polyvinyl chloride (PVC) is used for pipes, fencing, lawn chairs, handbags, curtains, non-food bottles, raincoats, toys, vinyl flooring, and electrical installation insulations.
    • Styrene Butadiene Rubber (SBR) is used as an adhesive and bonding agent.

    Classification of Polymers

    • Based on Origin of Source:
      • Natural polymers: Found in nature, e.g., cellulose, rubber, proteins.
      • Semi-synthetic polymers: Modified natural polymers, e.g., rayon, cellophane.
      • Synthetic polymers: Man-made polymers, e.g., polyethylene, nylon.
    • Based on Structure:
      • Linear polymers: Long, straight chains.
      • Branched chain polymers: Have side chains attached.
      • Cross-linked polymers: Chains connected by chemical bonds.
    • Based on Molecular Forces:
      • Elastomers: Highly elastic, can stretch and return to original shape, e.g., rubber.
      • Fibers: Long, thin strands with high tensile strength, e.g., cotton, nylon.
      • Thermoplastics: Soften on heating and solidify on cooling, recyclable, e.g., polyethylene, nylon.
      • Thermosets: Harden irreversibly on heating, strong and durable, not recyclable, e.g., Bakelite, epoxy resins.
    • Based on Mode of Polymerization:
      • Addition polymerization: Monomers add to form polymer without releasing small molecules, e.g., polyethylene, PVC.
      • Condensation polymerization: Monomers react, releasing small molecules like water, e.g., nylon, polyester.

    Mechanism of Addition Polymerization

    • In this process, monomers add together without losing small molecules.
    • The polymer formed is an exact multiple of the monomer unit.
    • Examples: Polyethylene, PVC, polypropylene.

    Classification of Polymers Based on Mode of Polymerization

    • Condensation Polymers:
      • Monomers react with loss of small molecules like water or HCl.
      • The polymer is not an exact multiple of the monomer unit.
      • Examples: Nylon, PET, Bakelite, Melamine-formaldehyde resin.

    Classification of Polymers Based on Molecular Forces

    • Elastomers:
      • High elasticity, tensile strength, flexibility, and resilience.
      • Return to original shape after deformation.
      • Examples: Natural rubber, polyurethanes, polybutadiene, silicone.

    Classification of Polymers Based on Molecular Forces

    • Fibers:
      • Long, thin strands with high tensile strength, flexibility.
      • Used in packaging, textiles, and non-woven fabrics.
      • Examples: Natural fibers - cotton, wool, silk. Synthetic fibers - polyester, nylon, acrylic.

    Classification of Polymers Based on Molecular Forces

    • Thermoplastics:
      • Soften on heating and solidify on cooling.
      • Held together by weak intermolecular forces.
      • Can be reshaped and recycled.
      • Examples: Polyethylene, nylon, polyvinyl chloride.

    Classification of Polymers Based on Molecular Forces

    • Thermosets:
      • Harden irreversibly on heating.
      • Molecules form a rigid, cross-linked network.
      • Strong, durable, and resistant to heat.
      • Not recyclable.
      • Examples: Vulcanized rubber, Bakelite, polyurethane, epoxy resin, vinyl ester resin.

    Difference Between Thermoplastics & Thermosetting Plastics

    • Thermoplastics:
      • Formed by addition polymerization.
      • Linear polymer chains.
      • Soften on heating, stiffen on cooling.
      • Can be remolded.
      • Usually soft, weak, less brittle.
      • Recyclable.
      • Soluble in some solvents.
    • Thermosetting Plastics:
      • Formed by condensation polymerization.
      • Three-dimensional network structure with strong covalent bonds.
      • Do not soften on heating.
      • Cannot be remolded.
      • Typically hard, strong, more brittle.
      • Not recyclable.
      • Insoluble in most solvents.

    Copolymers

    • Homopolymers: Synthesized from a single type of monomer.
    • Copolymers: Composed of two or more different monomer subunits linked together.

    Plastic Additives

    • Pigment: Adds color.
    • Stabilizer: Prevents degradation (breakdown).
    • Lubricant: Makes molding easier.
    • Filler: Adds strength.
    • Plasticizer: Increases flexibility.

    Videos

    • Learn about the history and discovery of vulcanized rubber, nylon, and Bakelite.

    Petrochemicals

    • Derived from natural gas liquids and oil refinery streams.
    • Used to make plastics, fibers, and other synthetic materials.

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    Related Documents

    AECH 1103 - Topic 4 Polymers And Petrochemicals PDF

    Description

    This quiz explores various common polymers, detailing their applications and classifications. You'll learn about materials like LDPE, HDPE, and PVC, including where they are commonly found. Test your knowledge on the properties and uses of these important substances.

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