Algebra Chapter 10
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Questions and Answers

Which of the following statements correctly describes addition polymerization?

  • It involves the liberation of by-products during the reaction.
  • It requires a minimum of two different monomers with functional groups.
  • It always produces a thermosetting plastic.
  • It occurs in the presence of multiple bonds in one or more monomers. (correct)

    • What is the glass transition temperature (Tg) of a polymer defined as?

  • The temperature where polymers become thermoplastic.
  • The temperature above which all polymers are always flexible.
  • The temperature below which an amorphous polymer is glassy and brittle. (correct)
  • The temperature at which a polymer starts to crystallize.

    • Which monomer is used to produce PVC?

  • CH2=CH2
  • CH2=CHCl (correct)
  • CF2=CF2
  • CH2=C(CH3)CO2CH3

    • What does knowing the Tg of a polymer help predict?

    <p>The flow properties and softening temperature of the polymer.</p> Signup and view all the answers

    Which of the following polymers is produced through condensation polymerization?

    <p>Nylon 6,6</p> Signup and view all the answers

    Which of the following is true about the properties of addition and condensation polymers?

    <p>Addition polymers typically yield thermoplastics, while condensation can yield thermosetting plastics.</p> Signup and view all the answers

    Which monomer is used to produce natural rubber?

    <p>CH2=CH C(CH3)=CH2</p> Signup and view all the answers

    What is the primary characteristic of condensation polymerization compared to addition polymerization?

    <p>It always liberates by-products such as water.</p> Signup and view all the answers

    Which property makes epoxy resin suitable for electrical insulation applications?

    <p>Good electrical insulation properties</p> Signup and view all the answers

    In which application is ABS co-polymer NOT commonly used?

    <p>Production of solar panels</p> Signup and view all the answers

    What distinguishes ABS from other plastics during its molding process?

    <p>Dimensionally stable with less shrinkage</p> Signup and view all the answers

    What benefit does using a solvent provide in polymerization?

    <p>It aids in the removal of heat of polymerization.</p> Signup and view all the answers

    Which of the following is NOT a property of epoxy resins?

    <p>Low modulus of elasticity</p> Signup and view all the answers

    What is a primary disadvantage of using solvents in polymer synthesis?

    <p>It may lead to low molecular weights due to chain transfer.</p> Signup and view all the answers

    Which temperature indicates the glass transition temperature (Tg) of ABS?

    <p>105 °C</p> Signup and view all the answers

    Which statement about suspension polymerization is accurate?

    <p>It separates the polymerization process into independent bulk polymerization nuclei.</p> Signup and view all the answers

    Which of the following stabilizers is NOT typically used in suspension polymerization?

    <p>Acetic acid</p> Signup and view all the answers

    What is a common characteristic of polypropylene (PP)?

    <p>It serves as both plastic and fiber.</p> Signup and view all the answers

    Which of the following statements about ABS co-polymer is true?

    <p>It has high surface brightness.</p> Signup and view all the answers

    What is a characteristic physical property of the product obtained from suspension polymerization?

    <p>The product has a narrow molecular weight distribution.</p> Signup and view all the answers

    What is a reason why suspension polymerization can be considered more economical?

    <p>It uses water as a heat transfer medium.</p> Signup and view all the answers

    What application does epoxy resin have in the construction industry?

    <p>Used as anti-corrosive paint on metal</p> Signup and view all the answers

    Which of the following describes a limitation of suspension polymerization?

    <p>It is not suitable for monomer-soluble initiators.</p> Signup and view all the answers

    What is one significant advantage of solvent use in polymerization?

    <p>It reduces thermal control difficulties.</p> Signup and view all the answers

    What is the number-average molecular weight (Mn) of a sample where 50% of the molecules have a molecular weight of 60000, 20% have 20000, and 30% have 40000?

    <p>43000</p> Signup and view all the answers

    In a polymer, if the weight-average molecular weight (Mw) is significantly higher than the number-average molecular weight (Mn), what does this indicate about the distribution of molecular weights?

    <p>The polymer is polydisperse.</p> Signup and view all the answers

    If a polymer sample consists of 40% of molecules with molecular weight 16000 and 10% with molecular weight 10000, what is the likely trend in the average molecular weight of the sample?

    <p>It will be significantly higher due to higher molecular weight presence.</p> Signup and view all the answers

    How do you calculate the weight-average molecular weight (Mw) of a polymer sample with molecular weights of 2×10, 3×10, and 1×10?

    <p>Multiply each molecular weight by its mole fraction and sum the results.</p> Signup and view all the answers

    What is the weight-average molecular weight (Mw) of a polymer consisting of 3 molecules with 30000 weight, 2 with 60000, and 5 with 10000?

    <p>39999</p> Signup and view all the answers

    If a polymer sample's number-average molecular weight is above 35000, which of the following could possibly be true about the sample's composition?

    <p>It includes a significant proportion of high molecular weight molecules.</p> Signup and view all the answers

    What is the significance of determining both Mn and Mw in a polymer sample?

    <p>To understand the distribution and behavior of the polymer chains.</p> Signup and view all the answers

    In the context of a polymer sample with molecular weights of 16000, 14000, 12000, and 10000 being proportioned 40%, 30%, 20%, and 10%, what would be the Mn and Mw of the sample?

    <p>14000 and 14300</p> Signup and view all the answers

    Which material exhibits the highest actuation strain?

    <p>Electroactive polymers (EAP)</p> Signup and view all the answers

    What is the typical force range of Electroactive polymers (EAP)?

    <p>0.1 - 3 MPa</p> Signup and view all the answers

    Which statement regarding the drive voltage requirements for materials is true?

    <p>Shape memory alloys (SMA) does not require drive voltage.</p> Signup and view all the answers

    What is a crucial factor affecting the biodegradation of polymers?

    <p>The presence of micro-organisms</p> Signup and view all the answers

    Which type of material has the fastest reaction speed?

    <p>Electroactive polymers (EAP)</p> Signup and view all the answers

    Which factor does NOT significantly influence biodegradable reactions?

    <p>Color of the environment</p> Signup and view all the answers

    How does the force generation of shape memory alloys (SMA) compare to that of electroactive ceramics (EAC)?

    <p>SMA generates considerably more force than EAC.</p> Signup and view all the answers

    Which statement regarding the fracture toughness of materials is accurate?

    <p>Shape memory alloys (SMA) are elastic.</p> Signup and view all the answers

    Study Notes

    Molecular Weight Calculations

    • Ni = Number of molecules
    • Mi = Molecular weight of each type of molecule
    • Number-average molecular weight (Mn) calculated from molecular weights and quantities
    • Weight-average molecular weight (Mw) signifies the average considering mass distribution
    • Polydispersity Index (PDI) indicates the distribution of molecular weights in a polymer sample

    Addition Polymers

    • Common addition polymers include:
      • LDPE & HDPE: Derived from ethylene (CH2=CH2)
      • PVC: Derived from vinyl chloride (CH2=CHCl)
      • Orlon: Derived from acrylonitrile (CH2=CHCN)
      • Teflon: Derived from tetrafluoroethylene (CF2=CF2)
      • PMMA: Derived from methacrylic acid (CH2=C(CH3)CO2CH3)
      • Natural rubber: Derived from isoprene (CH2=CH C(CH3)=CH2)

    Condensation Polymerization

    • Requires at least two different monomers with functional groups
    • By-products like water (H2O) released during the polymerization process
    • Chain growth occurs at two active centers, both in thermosetting and thermoplastic polymers

    Glass Transition Temperature (Tg)

    • Tg indicates temperature where polymer transitions from a hard, brittle state to a soft, flexible state
    • Significance:
      • Anticipates flow properties and softening temperatures
      • Facilitates comparison of polymer samples for functional applications
      • Provides insights into thermal expansion and flexibility

    Suspension Polymerization

    • Water-insoluble monomers are polymerized in fine droplets suspended in water
    • Aqueous phase serves as an efficient heat transfer medium
    • Droplet size depends on monomer-to-water ratio and stabilizer concentration
    • Results in narrower molecular weight distribution and is economical due to the use of water

    Applications of Specialty Polymers

    • Epoxy Resins
      • Used in surface coatings, adhesives, and electrical insulators
      • Excellent structural strength, low shrinking during curing
    • ABS Copolymer
      • Made from acrylonitrile, butadiene, and styrene
      • Exhibits high tensile strength, flexibility, and corrosion resistance
      • Applications in automotive parts and electronic enclosures

    Properties of Polypropylene (PP)

    • Versatile polymer utilized in plastics and fibers
    • Acts efficiently as both a plastic and a flexible material

    Bio-based and Biodegradable Polymers

    • Break down via bacterial decomposition or enzymatic reactions
    • Examples of natural biopolymers include cellulose and keratin
    • Factors affecting biodegradation:
      • Microorganisms: Various species aid in degradation
      • Environment: Temperature, moisture, salts, and pH crucial for microbial activity
      • Polymer nature: Presence of hydrolysable or oxidizable bonds influences breakdown speed

    Comparison of Smart Materials

    • Electroactive Polymers (EAP): High actuation strain (>10%), low density (1-2.5 g/cc)
    • Shape Memory Alloys (SMA): Lower actuation strain (<8%), high force (around 700 MPa)
    • Electroactive Ceramics (EAC): Very low reaction speed; generally fragile compared to polymers

    These notes encapsulate critical aspects of polymer chemistry and engineering applications for a foundational understanding of the subject matter.

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    Description

    This quiz focuses on concepts covered in Algebra Chapter 10, emphasizing calculations involving numerical values and their weighted averages. Test your understanding of solving equations and applying mathematical operations effectively.

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