Questions and Answers
What are the classifications of polymers?
What are natural polymers commonly found in?
Plants and animals
Name two examples of natural polymers.
Proteins and cellulose
What is cellulose composed of?
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What are semi-synthetic polymers?
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What are man-made (synthetic) polymers?
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What are three parameters for the classification of polymers?
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What are the two types of chemical structures in polymers?
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What is the difference between homopolymers and co-polymers?
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List the three types of polymers based on polymeric structures.
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Describe linear polymers.
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What characterizes branched polymers?
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What defines cross-linked polymers?
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What does tacticity refer to in polymers?
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What are the three types of tacticity?
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What does the backbone of polymers consist of?
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What are thermoplastics?
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How do thermoset materials behave when heated?
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What are elastomers?
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Study Notes
Classification of Polymers
- Polymers fall into three main categories: Natural, Semi-synthetic, and Man-made (synthetic).
Natural Polymers
- Naturally occurring polymers found in plants and animals often consist of a single type of monomer.
Examples of Natural Polymers
- Proteins: Present in both plants and animals.
- Cellulose: A polysaccharide derived from plants composed of sugar monomers.
- Natural rubber: Harvested from the latex of tropical plants.
Semi-synthetic Polymers
- Derived from natural polymers that have been chemically modified.
Man-made (Synthetic) Polymers
- Created in laboratories or industrial factories.
- Examples include:
- Nylon: Commonly used in clothing.
- Teflon: Used for non-stick cooking utensils.
- Epoxy resins: Utilized as binders in countertops and floor coatings.
Classification Parameters
- Polymers can be classified based on:
- Chemical Structures
- Polymeric Structures
- Tacticity
- Thermal behavior
- Molecular forces
- Methods of synthesis
Chemical Structures
- Two types:
- Homopolymers: Consist of identical monomers (e.g., A-A-A).
- Co-polymers: Combination of two different monomers (e.g., A-B-A-B).
Comparison of Homopolymers and Co-polymers
- Homopolymers: Formed through addition polymerization, exhibit simple structures, and include examples such as PVC and polyethylene.
- Co-polymers: Formed via condensation polymerization, tend to have complex structures, and include examples like polyvinyl acetate and butadiene rubber.
Polymeric Structures
- Three types:
- Linear: Long, straight chains providing density and high melting points.
- Branched: Feature branches off a linear chain, resulting in lower density and melting points.
- Cross-linked: Chains are chemically bonded, producing strong, stable materials that are difficult to recycle.
Tacticity
- Refers to the stereochemistry of polymer arrangements.
- Three types:
- Isotactic: Substituents on the same side of the polymer backbone.
- Syndiotactic: Substituents in alternating positions.
- Atactic (heterotactic): Substituents randomly positioned along the backbone.
Polymer Backbones
- Composed primarily of hydrocarbons.
Thermoplastics
- Characterized by linear or branched structures held by intermolecular forces (Van der Waals).
- They soften when heated and can be reshaped upon cooling.
- Example: ABS (Acrylonitrile Butadiene Styrene), used in toys and safety gear.
Thermosets
- Form cross-linked structures upon heating, creating irreversible reactions.
- Retain strength and structure at high temperatures.
- Example: Bakelite, used in electrical outlets and kitchenware.
Elastomers
- Known as "elastic polymers," these can stretch and return to their original shape due to long chain polymers with weak intermolecular forces.
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Description
Explore the classification of polymers through these flashcards. Learn about the different categories such as natural, semi-synthetic, and synthetic polymers, along with examples found in nature. This is a useful resource for students studying materials science or chemistry.
