Polymeric Materials Chapter 3
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Questions and Answers

Which of the following is NOT a type of synthetic polymer?

  • Polystyrene (PS)
  • Nylon
  • Polyethylene (PE)
  • Natural rubber (correct)

    • All synthetic polymers are biodegradable.

    False

    What is a random copolymer?

    A copolymer in which the different types of monomers are arranged randomly.

    ___ polymers are human-made and can be classified into thermoplastics, thermosets, and elastomers.

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

    Which type of polymer is known for being elastic?

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

    Match the following types of synthetic polymers with their properties:

    <p>Thermoplastics = Melt upon heating Thermosets = Set permanently when cured Elastomers = Flexible and rubber-like Synthetic fibers = Used in textiles</p> Signup and view all the answers

    Name one example of a biodegradable polymer.

    <p>Natural rubber</p> Signup and view all the answers

    Biopolymers include materials such as ___ and starch.

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

    What is the fundamental building block of a polymer called?

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

    A homopolymer is made from multiple types of monomers.

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

    Which of the following is a natural polymer?

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

    What does DP stand for in the context of polymers?

    <p>Degree of Polymerization</p> Signup and view all the answers

    Polycaprolactone (PCL) is classified as a natural polymer.

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

    A ______ is a polymer chain that consists of a single atom type.

    <p>homochain polymer</p> Signup and view all the answers

    What type of polymer contains more than one atom type in the backbone?

    <p>Heterochain polymer</p> Signup and view all the answers

    What are the three classifications of polymers based on their structure?

    <p>Linear, Branched, Network (Crosslinked)</p> Signup and view all the answers

    Polymerization that involves adding monomers one by one to form a polymer is called __________.

    <p>Addition polymerization</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>End groups = Structural units that terminate polymer chains Living Polymers = Polymers capable of further polymerization Homopolymer = Made from a single type of monomer Copolymer = Made from two or more different types of monomers</p> Signup and view all the answers

    Match the following types of branched polymers with their characteristics:

    <p>Star = Several linear chains connected at one point Dendrimer = Near spherical shapes with generation numbers up to 5-7 Comb = High number of similarly long side chains</p> Signup and view all the answers

    Telechelic polymers contain reactive end groups that can undergo polymerization.

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

    Calculate the degree of polymerization (DP) for PVC if its molecular weight (Mn) is 21,150 g/mol and the repeat unit molecular weight is 62.496 g/mol.

    <p>338.42</p> Signup and view all the answers

    What type of polymer is cellulose nitrate classified as?

    <p>Semi-synthetic polymer</p> Signup and view all the answers

    Star polymers are used primarily as viscosity modifiers in high-performance engine oils.

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

    The __________ density of a network polymer is related to its hardness.

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

    Which process involves the removal of small molecules to form a polymer?

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

    In addition polymerization, all monomer atoms are included in the final polymer structure.

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

    What small molecule is expelled during the formation of Nylon-6,6?

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

    In __________ polymerization, the reactive site is consumed during the process, leading to termination.

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

    Match the following types of polymerization with their characteristics:

    <p>Addition polymerization = Incorporates all atoms from the monomers Condensation polymerization = Generates by-products like water or HCl Nylon-6,6 = Formed from adipoyl chloride and hexamethylene diamine Termination = Ends the growth of the polymer chain</p> Signup and view all the answers

    What is a common feature of both addition and condensation polymerization?

    <p>Both result in the formation of a polymer</p> Signup and view all the answers

    What type of polymerization occurs when part of the monomer is eliminated during the process?

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

    Thermoplastic polymers cannot be remelted or reshaped once they are cooled.

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

    The reactive site in a polymer chain remains indefinitely active in addition polymerization.

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

    What is one common characteristic of elastomers?

    <p>They stretch and return to their original form.</p> Signup and view all the answers

    Which phase boundary aspect allows for continued reaction in condensation polymerization?

    <p>Removing the polymer</p> Signup and view all the answers

    A thermosetting polymer is typically stronger than a __________ polymer.

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

    Match the type of polymer with its description:

    <p>Thermoplastic = Can be remelted and remolded Thermoset = Cross-linked and cannot be melted Elastomer = Can stretch and return to original shape Addition polymerization = No part of the monomer is eliminated</p> Signup and view all the answers

    What is the glass transition temperature (Tg)?

    <p>The temperature at which a polymer becomes hard and brittle.</p> Signup and view all the answers

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

    <p>Rubber bands</p> Signup and view all the answers

    Melting temperature (Tm) and glass transition temperature (Tg) are the same for polymers.

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

    All elastomers are classified as thermosetting polymers.

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

    What is the role of NaOH in the synthesis of Nylon 6,6?

    <p>It acts as a catalyst in the reaction.</p> Signup and view all the answers

    What happens to polymer chains during melting?

    <p>The chains fall out of their crystal structures and become a disordered liquid.</p> Signup and view all the answers

    Rubber elastomers like polyisoprene are used above their _____ state.

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

    Which of the following materials is likely used below its glass transition temperature?

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

    Match the following polymers with their respective states at Tg:

    <p>Polystyrene = Glassy state Polyisoprene = Rubbery state Polyisobutylene = Rubbery state Crystalline polymers = Glassy state and melting</p> Signup and view all the answers

    The amorphous portion of a crystalline polymer undergoes glass transition.

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

    What percentage of a typical crystalline polymer sample is usually amorphous?

    <p>40-70%</p> Signup and view all the answers

    Study Notes

    Chapter 3: Polymeric Materials

    • The presentation is about polymeric materials, specifically focusing on different types of polymers, their properties, and polymerization methods.
    • The presenter is Dr. Nur Nabilah Shahidan, and the presentation room is BSP 2.18.

    Outline

    • 7.1 Polymerization and Properties of Polymers: This section discusses the process of polymerization and the resulting properties of polymers.
    • 7.2 Effect of Structural Modification and Temperature on Properties of Polymers: This section examines how structural changes and temperature variations affect polymer properties.
    • 7.3 High-Strength Thermoplastics: This section focuses on high-strength thermoplastic materials.

    What is a Polymer?

    • A polymer is a large molecule made up of repeating small building blocks called monomers.
    • Monomers are the building blocks of polymers.
    • The structure of the repeating unit in a polymer depends on the monomer used.

    Definitions of Common Polymer Terms

    • Repeating Unit: The fundamental repeating structural unit in a polymer chain, which depends on the monomer used in the synthesis process.

    • Base Unit: The smallest possible repeating unit; independent of the synthetic route.

    • Degree of Polymerization (DP): The average number of repeating units per chain, calculated as the ratio of the number-average molecular weight (Mn) to the molecular weight of a repeating unit (m).

    • End Groups: Structural units terminating a polymer chain.

    • Living Polymers/Telechelic Polymers: Macromonomers or oligomers with reactive end groups capable of undergoing polymerization (usually by heat), leading to network polymers.

    Types of Atoms in Polymer Backbone

    • Homochain Polymer: Polymer chain (backbone) consisting of a single atom type.
    • Heterochain Polymer: Polymer chain (backbone) containing more than one atom type.

    Order of Repeating Units in Backbone

    • Homopolymer: Polymer made from a single monomer.
    • Copolymer: Polymer made from more than one type of monomer.
    • Different types of copolymers exist, including random, block, alternating and graft copolymers, each offering specific properties.

    Classification of Polymers

    • Polymers are classified by their origin (synthetic, bio, semi-synthetic), structure (linear, branch chain, cross-linked, network), types (thermosets, thermoplastics, elastomers), and polymerization types (addition, condensation).

    Synthetic Polymers

    • These are human-made polymers.
    • They are categorized into thermoplastic, thermoset, elastomers, and synthetic fibers.
    • Common examples include low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), nylon, and Teflon (PTFE).

    Biopolymers

    • These are polymers occurring naturally.
    • Examples include natural rubber, natural silk, cellulose, starch, proteins.
    • These polymers are biodegradable.

    Semi-Synthetic Polymers

    • Polymers obtained by treating natural polymers with simple chemical processes to alter their properties.
    • Cellulose nitrate is an example.

    Classification by Structure

    • Linear: No branching aside from pendant groups.
    • Branched: May have only a few side chains or many side chains per repeating unit.
    • Network/Crosslinked: Crosslink density related to hardness; average of more than two crosslinks per chain forming an infinite network.
    • Star polymers: Several linear polymer chains connected at one point.
    • Dendrimers: Highly branched, near-spherical shapes.
    • Comb polymers: High number of side chains all similar in length originating from macromonomers.

    Classification Based on Polymerisation Types

    • Polymerization: A chemical process creating polymers from monomers.
    • Addition Polymerization: Monomers add one by one to an active site on the growing chain, with no byproducts (e.g., polyethylene from ethylene). The mechanism includes initiation, propagation, termination.
    • Condensation Polymerization: Formation from monomers with the loss of small molecules like water, alcohol, or ammonia (e.g., nylon). This reaction differs from addition polymerization by the expulsion of small molecules like HCl gas.

    Types of Polymers

    • Thermoset: Cross-linked polymer, not meltable.
    • Thermoplastic: Meltable plastic.
    • Elastomer: Polymer that stretches and returns to its original shape and may be thermoplastic or thermoset.

    Thermosetting and Thermoplastic Properties

    • Thermoplastics: Melts and can be re-molded.
    • Thermosets: Can't be re-melted and decompose when heated.

    Examples of Thermoplastics

    • Polyethylene (PE)
    • Poly(vinyl chloride) (PVC)
    • Polytetrafluoroethylene (PTFE)
    • Polypropylene (PP)

    Elastomers

    • Elastomers are flexible polymers that can be deformed under force, but they return to their original shape once the stress is removed.
    • Covalent bonds (cross-links) between polymer chains enable the elastic behavior

    Effect of Temperature on Properties

    • Glass Transition Temperature (Tg): The temperature at which a polymer transitions from a hard, brittle state to a softer, more flexible state.
    • Melting Temperature (Tm): The temperature at which a polymer transitions from a solid to a liquid state (crystalline polymers only).

    Polymer Crystallinity

    • Polymers are rarely 100% crystalline.
    • Crystalline regions are difficult to form with all chains aligned, leading to amorphous regions alongside crystalline regions in polymers.

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    Polymeric Materials PDF

    Description

    Explore the fascinating world of polymeric materials in this quiz based on Chapter 3. Delve into the processes of polymerization, the impact of structural modifications, and the characteristics of high-strength thermoplastics. Test your understanding of how these materials are formed and their unique properties.

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