Polymers - Definition and Classification
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Questions and Answers

What significant contribution did Hermann Staudinger make to the field of polymer science in 1927?

Hermann Staudinger published his research work entitled 'Uber Polymerisation', which was pivotal in the development of modern polymer theory.

In what year did production of polyvinyl chloride (PVC) resin begin, and what are its primary applications?

Production of polyvinyl chloride resin began in 1927, and it is primarily used to make plumbing lines, pipes, and bottles.

Identify two notable polymers invented in the 1930s and state their uses.

Nylon was synthesized by W. Carothers and is used for ropes, while polystyrene is widely used in packaging, including videocassettes.

What are the two types of polyethylene developed in 1941, and what are their common applications?

<p>Low density and high density polyethylene were developed, commonly used for manufacturing packaging films, pipes, and toys.</p> Signup and view all the answers

How did the polymer plastic industry change by 1976, and what notable polymer was developed by S. Kwolek in 1971?

<p>By 1976, the polymer plastic industry outstripped steel as the most widely used material. S. Kwolek developed Kevlar, a polymer capable of withstanding temperatures of 300 °C.</p> Signup and view all the answers

What is a polymer and how is it formed?

<p>A polymer is a macromolecule formed by linking together many monomers. These monomers are small molecules that repeat to create a long chain.</p> Signup and view all the answers

Define the term 'degree of polymerization' in the context of polymers.

<p>The degree of polymerization refers to the number of repeating units or monomers in a polymer chain. It determines the size of the polymer.</p> Signup and view all the answers

List the four classes of large biomolecules and their respective monomer units.

<p>The four classes are: Carbohydrates (sugars), Lipids (fatty acids), Proteins (amino acids), and Nucleic Acids (nucleotides).</p> Signup and view all the answers

What is the significance of vulcanization in rubber production?

<p>Vulcanization makes natural rubber more stable and durable by heating it with sulfur. This process significantly enhances its properties for practical applications like tires.</p> Signup and view all the answers

Explain the difference between a polymer and an oligomer.

<p>A polymer consists of a large number of repeating units, while an oligomer contains only a few monomers linked together. Polymers have higher molecular weights compared to oligomers.</p> Signup and view all the answers

What was Bakelite, and why was it significant in the history of synthetic plastics?

<p>Bakelite was the first synthetic plastic, synthesized by Leo Baekeland in 1907. It was significant for its hardness and high heat resistivity, making it a valuable electrical insulator.</p> Signup and view all the answers

Describe the role of monomers in the formation of macromolecules.

<p>Monomers are the basic building blocks of macromolecules, as they bond together to form long polymer chains. The properties of the resulting macromolecule depend on the types and arrangements of these monomers.</p> Signup and view all the answers

How did British Explorers contribute to our understanding of polymetric materials in the Mayan Civilization?

<p>British Explorers documented the use of natural rubber by the Mayans, who created balls from it, showcasing one of the earliest applications of polymeric materials. This historical insight highlights the long-standing use of polymers in human culture.</p> Signup and view all the answers

What distinguishes addition polymerization from condensation polymerization in terms of by-products?

<p>Addition polymerization does not produce by-products, while condensation polymerization typically results in by-products such as water or HCl.</p> Signup and view all the answers

Explain the significance of molecular mass in addition polymerization compared to condensation polymerization.

<p>In addition polymerization, the polymer molecular mass is an integral multiple of the monomer's mass, whereas in condensation polymerization, the polymer molecular mass is not an integral multiple.</p> Signup and view all the answers

Describe the role of reaction time in achieving higher molecular weight polymers in condensation polymerization.

<p>Longer reaction times are necessary for condensation polymerization to yield higher molecular weight polymers, as the molecular mass increases steadily with time.</p> Signup and view all the answers

What is co-polymerization and provide an example?

<p>Co-polymerization is the process of polymerizing two or more different monomer species together, such as in the production of styrene butadiene rubber, also known as Buna-S.</p> Signup and view all the answers

What types of mechanisms can addition polymerization follow?

<p>Addition polymerization can follow free radical or ionic mechanisms, including cationic or anionic processes.</p> Signup and view all the answers

How do the molecular species present in the reaction mixture differ between addition and condensation polymerization at any given stage?

<p>In addition polymerization, the reaction mixture contains monomers, higher polymers, and a small fraction of growing chains, while in condensation polymerization, it contains all types of molecular species including monomers, oligomers, and polymers.</p> Signup and view all the answers

Why are condensation polymerization reactions generally slower than addition polymerization?

<p>Condensation polymerization reactions are slower because they involve the reaction of two molecular species and often need longer timeframes to reach higher molecular weights.</p> Signup and view all the answers

Compare the types of polymers produced by addition polymerization and condensation polymerization.

<p>Addition polymerization typically yields homo-chains, while condensation polymerization results in hetero-polymer chains.</p> Signup and view all the answers

What are the primary monomers that constitute starch and cellulose?

<p>Starch is a polymer of α-D-glucose, while cellulose is a polymer of β-D-glucose.</p> Signup and view all the answers

Identify the polymer formed by cis-isoprene and its common use.

<p>Natural rubber is the polymer formed by cis-isoprene and is commonly used for making tires and elastic materials.</p> Signup and view all the answers

How are biopolymers classified based on their biodegradability?

<p>Biopolymers can be classified as biodegradable or non-biodegradable based on their ability to break down in the environment.</p> Signup and view all the answers

What is the difference between low density polyethylene (LDPE) and high density polyethylene (HDPE)?

<p>LDPE has a branched structure, making it flexible and less dense, while HDPE has a linear structure, resulting in greater strength and rigidity.</p> Signup and view all the answers

Name two synthetic polymers and their main applications.

<p>Polyethylene (PE) is used for making bottles and insulation parts, while Nylon is primarily used in textiles and ropes.</p> Signup and view all the answers

What type of polymer is commonly used as an adhesive and give an example?

<p>Liquid resins are commonly used as adhesives, with epoxy adhesives being a prime example.</p> Signup and view all the answers

What are elastomers and what is their key characteristic?

<p>Elastomers are a type of polymer that can undergo significant elastic deformation and return to their original shape, such as vulcanized rubber.</p> Signup and view all the answers

What properties make HDPE suitable for use in high-impact applications?

<p>HDPE has high tensile strength, stiffness, and impact resistance due to its closely packed molecular structure.</p> Signup and view all the answers

What are the two functional groups present in urethane?

<p>The two functional groups in urethane are an O-R group and an NH-R group.</p> Signup and view all the answers

What is the primary method of preparing polyurethanes?

<p>Polyurethanes are prepared by the polymerization of a di-isocyanate and ethylene glycol.</p> Signup and view all the answers

What effect does a blowing agent have in the production of polyurethane?

<p>A blowing agent causes the formation of polyurethane foam during production.</p> Signup and view all the answers

In what applications is polyurethane foam commonly used?

<p>Polyurethane foam is used for furniture stuffing, carpet backings, and insulation.</p> Signup and view all the answers

What is a key advantage of polyurethane material regarding load capacity?

<p>Polyurethane has high load capacity in both tension and compression and can return to its original shape.</p> Signup and view all the answers

Who demonstrated the creation of polyurethane foam and in what year?

<p>Prof. Otto Bayer demonstrated the creation of polyurethane foam in 1952.</p> Signup and view all the answers

What are some benefits of using polyurethane materials in electrical applications?

<p>Polyurethanes exhibit good electrical insulating properties.</p> Signup and view all the answers

How does polyurethane demonstrate stability in different environmental conditions?

<p>Polyurethane remains stable with minimal swelling in water, oil, and grease.</p> Signup and view all the answers

What is the primary difference between Bakelite and Novolac?

<p>Bakelite is a cross-linked polymer, while Novolac is a linear polymer chain.</p> Signup and view all the answers

List three properties of Bakelite.

<p>Bakelite is rigid, hard, and resistant to non-oxidising acids.</p> Signup and view all the answers

What is one main use of epoxy resin in manufacturing?

<p>Epoxy resin is commonly used as an adhesive for glass and metals.</p> Signup and view all the answers

Why is vulcanization important for natural rubber?

<p>Vulcanization cross-links rubber, transforming it into a more durable material that can withstand stretching.</p> Signup and view all the answers

What challenges are associated with recycling epoxy resin?

<p>Epoxy resin cannot be reclaimed from waste and, therefore, cannot be recycled.</p> Signup and view all the answers

What role do polar groups play in the properties of epoxy resin?

<p>Polar groups in epoxy resin provide excellent adhesive properties.</p> Signup and view all the answers

Identify a key application of Bakelite and explain why it is suitable for that use.

<p>Bakelite is used in electrical insulator parts due to its excellent electrical insulating properties.</p> Signup and view all the answers

How can cold weather affect natural rubber?

<p>Cold weather can make natural rubber brittle and prone to cracking.</p> Signup and view all the answers

Flashcards

Polymer

A large molecule formed by linking many similar small molecules (monomers) together.

Monomer

A small molecule that is the building block of a polymer.

Degree of Polymerization

The number of repeating units in a polymer chain.

Macromolecule

A large molecule composed of thousands of covalently bonded atoms.

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Oligomer

A molecule comprised of a few monomers bonded together.

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Vulcanization

The process of treating natural rubber with sulfur to improve its stability and strength.

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Bakelite

An early synthetic plastic, known for its hardness and heat resistance.

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Four classes of biomolecules

Carbohydrates, lipids, proteins, and nucleic acids are large biological molecules.

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Nylon invention year

Nylon was synthesized in 1938 by W. Carothers.

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Polyvinyl chloride (PVC) use

PVC resin is used to make plumbing lines, pipes, and bottles.

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Polyethylene development year

Polyethylene was developed in 1941.

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Kevelar's high-temp use

Kevelar, a polymer, can withstand a temperature of 300°C.

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Polystyrene use cases

Polystyrene is used in videocassettes and packaging.

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Addition Polymerization

A type of polymerization where monomers join together to form a polymer in a chain-like reaction without any loss of atoms.

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Condensation Polymerization

A type of polymerization where monomers react together with the elimination of a small molecule like water or HCl.

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Chain Growth Polymerization

Another term for addition polymerization

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Step Growth Polymerization

Another term for condensation polymerization

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Co-polymerization

The polymerization of two or more different monomers to produce a copolymer.

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Polymer Molecular Mass (Addition)

An exact multiple of the original monomer unit's molecular mass.

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Polymer Molecular Mass (Condensation)

Not an exact multiple of the original monomer unit's molecular mass.

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Byproduct in Condensation polymerization

Small molecules like water or HCl are eliminated during the reaction.

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Natural polymers

Polymers found in nature, formed by living organisms. Examples include starch, cellulose, and natural rubber.

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Starch

A natural polymer composed of α-D-glucose units, providing energy storage in plants.

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Cellulose

A natural polymer composed of β-D-glucose units, forming the structural framework of plants.

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Natural rubber

A natural polymer composed of cis-isoprene units, known for its elasticity.

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Synthetic polymers

Polymers created by humans through chemical processes, like polyethylene (PE), polystyrene (PS), and nylon.

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Biodegradable polymer

A synthetic polymer that can be broken down by microorganisms in nature.

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Plastic

A type of synthetic polymer that is hard and tough, often used in everyday objects.

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Elastomer

A type of synthetic polymer that exhibits high elasticity, similar to natural rubber.

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Urethane

A compound with an O-R group and an NH-R group attached to the same carbonyl carbon.

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Polyurethane

A thermosetting polymer (usually) formed by polymerizing a di-isocyanate with ethylene glycol.

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Polyurethane Foam

A type of polyurethane formed in the presence of a blowing agent, creating air pockets for a spongy texture.

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Blowing Agent

A substance used in the production of polyurethane foam to introduce gas bubbles, leading to a lighter, less dense material.

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Methylene Diphenylisocyanate

A common monomer used in the production of polyurethane.

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Polyurethane Properties

Polyurethanes are strong, elastic, and resistant to water, oil, and grease. They also have good electrical insulating properties.

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Polyurethane Applications

Polyurethane foam is used in furniture, carpet backing, and insulation. Other applications include elastic fabrics (spandex), paints and varnishes, and solid tires.

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Novolac

A linear polymer formed by the reaction of phenol and formaldehyde, used as a precursor for Bakelite.

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Epoxy Resin Properties

Epoxy resins are strong adhesives with high resistance to chemicals, water, and heat.

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Epoxy Resin Uses

Epoxy resins are used in coatings, adhesives, and fiberglass-reinforced plastics, often in construction and manufacturing.

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Polyisoprene and Rubber

Natural rubber is a polymer made of polyisoprene, which can also be produced synthetically.

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Crosslinking in Rubber

The process of adding cross-links to rubber molecules, making it stronger and less likely to deform permanently.

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Recyclability of Thermosets

Thermosetting plastics, like Bakelite and epoxy resins, cannot be melted and reshaped, making them difficult to recycle.

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Study Notes

Polymers - Definition and Classification

  • Polymers are large macromolecules composed of thousands of covalently bonded atoms.
  • Polymers are built from monomers, which are smaller building-block molecules.
  • A polymer is a long molecule consisting of many similar building blocks.
  • The four classes of large biomolecules are carbohydrates, lipids, proteins, and nucleic acids.
  • These macromolecules are polymers built from monomers, such as sugars for carbohydrates, fatty acids for lipids, amino acids for proteins, and nucleotides for nucleic acids.
  • A species that has only a few monomers bonded together is called an oligomer.

Polymer Definition

  • Polymers are macromolecules formed by linking together a large number of small molecules.
  • Polymers exhibit high molecular weight.
  • The degree of polymerization (n) is the number of repeating units in a polymer.

History of Polymers

  • Mayan civilization used polymers in their children's' games.
  • 1839: Charles Goodyear discovered vulcanization, improving natural rubber.
  • 1907: Leo Baekeland synthesized Bakelite, the first synthetic plastic.
  • 1917: M. Polanyi discovered the chemical structure of cellulose using X-ray crystallography.
  • 1920: Staudinger published research on polymer theory.
  • 1927: Polyvinyl chloride resin production began.
  • 1930: Polystyrene was invented.
  • 1938: Nylon was synthesized.
  • 1941: Polyethylene started to be used.
  • 1970: Mouldable high temperature polymers were developed.
  • 1971: Kevlar was developed.
  • 1976: The polymer plastic industry surpassed steel in usage.

Types of Polymerization Reactions

  • Addition (Chain Growth): Exact multiples of the original monomer molecules. E.g., polymerization of ethylene forms polyethylene.
  • Condensation (Step Growth): Molecules react with the removal of a small molecule like water. E.g., formation of Nylon-6,6 from hexamethylene diamine and adipic acid.
  • Co-Polymerization: Joint polymerization of two or more different monomer species. E.g., formation of styrene-butadiene rubber (SBR).

Polymer Classification

  • Based on Source:
    • Natural polymers - cellulose, starch, protein, natural rubber
    • Synthetic polymers - polyethylene, polystyrene, nylon, PVC, Bakelite
  • Based on Biodegradability:
    • Biodegradable polymers - poly(hydroxypentanoate), other biopolymers
    • Non-biodegradable polymers - poly(vinyl acetate), polystyrene
  • Based on Form and Use:
    • Plastics - hard and tough materials
    • Elastomers - vulcanized rubber with good strength and elongation
    • Fibres - used for reinforcement and support in structures
    • Liquid resins - used as adhesives, sealants, etc.

Polymer Nomenclature

  • Homo polymer: A single type of monomer. E.g., polyethylene.
  • Copolymer: Different types of monomers. E.g., styrene-butadiene rubber.
  • Linear, branched, cross-linked: Different arrangements of monomers in the polymer chain.

Tacticity (Stereochemistry of Polymers)

  • Isotactic: All side groups are oriented on the same side of the polymer chain.
  • Syndiotactic: Side groups alternate on opposite sides of the polymer chain.
  • Atactic: Side groups are randomly arranged.

Properties and Uses of Common Polymers

  • Polyethylene (PE): Rigid, waxy white, translucent, thermoplastic material. Used as injection and extrusion molding material (insulators, bottle caps, flexible bottles).
  • Polyvinyl Chloride (PVC): Colourless, odourless, chemically inert powder. Resistant to light, chemicals, and heat. Used in pipe work, tank lining, safety helmets, and refrigerator components.
  • Polymethyl Methacrylate (PMMA): Hard and fairly rigid material. High optical transparency, resistant to sunlight. Used in lenses, aircraft light fixtures, and TV screens.
  • Polytetrafluoroethylene (PTFE): High regular, crystalline powder. High chemical resistance (strong acids, solvents). Used as non-stick coating in cookware, insulation, and leakproof tapes.
  • Bakelite: Hard, scratch-resistant, infusible solid. Excellent electrical insulator. Used in electrical parts, molded items, and impregnating materials.
  • Epoxy Resin: Thermosetting plastic. Cannot be recycled. Used as a surface coating, adhesive, glass-fibre reinforcement, and components in aircraft/automobiles.
  • Polyisoprene (Rubber): Natural, can be synthesized, becomes brittle in cold weather.
  • Polyesters: Strong, durable and hydrophobic. Used in fabrics, insulation, and packaging. A common type is polyethylene terephthalate (PET).

Polymer Synthesis

  • Condensation polymerization, addition polymerization

Effect of Polymer Structure on Properties

  • Mechanical Properties:
    • Strength depends on the magnitude and distribution of forces between polymer chains (e.g., van der Waals forces, covalent bonds).
    • Plastic deformation is the change in shape of the polymer due to heat or pressure.
  • Physical Properties:
    • Crystallinity relates to the ordered arrangement of polymer chains, which affects density, melting point, and strength.
  • Thermal Properties:
    • Glass transition temperature (Tg) is the temperature at which a polymer transitions from a hard, glassy state to a soft, rubbery state. Higher molecular weight and crystalline structure leads to higher Tg.
  • Chemical Properties:
    • Polymer resistance towards various chemicals (acids, solvents, water, etc)

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Explore the fascinating world of polymers, their definitions, classifications, and the monomers that compose them. This quiz covers the four classes of large biomolecules and the history of polymers. Test your knowledge on these essential macromolecules used in various applications.

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