Types of polymers, polymerization, and common polymers (e.g., polyethylene, PVC)

1. Definition of Polymers

  1. Polymers are large molecules made by repeating structural units called monomers.
  2. The process of forming polymers from monomers is called polymerization.
  3. Polymers can be natural (e.g., rubber, proteins) or synthetic (e.g., plastics).

2. Types of Polymers Based on Origin

  1. Natural Polymers: Found in nature, e.g., cellulose, starch, proteins.
  2. Semi-synthetic Polymers: Derived from natural polymers, e.g., rayon.
  3. Synthetic Polymers: Man-made, e.g., nylon, polyethylene.

3. Types of Polymers Based on Structure

  1. Linear Polymers: Long chains with no branches, e.g., polyethylene.
  2. Branched Polymers: Chains with side branches, e.g., low-density polyethylene (LDPE).
  3. Cross-linked Polymers: Chains interconnected by bonds, e.g., vulcanized rubber.

4. Types of Polymerization

  1. Addition Polymerization: Monomers add together without loss of any molecule, e.g., polyethylene.
  2. Condensation Polymerization: Monomers join with the elimination of small molecules (like water), e.g., nylon, polyester.
  3. Copolymerization: Two or more different monomers polymerize together, e.g., SBR (styrene-butadiene rubber).

5. Common Polymers and Their Applications

  1. Polyethylene: Used in packaging, bottles, and containers. Types:
    • LDPE: Flexible and used for plastic bags.
    • HDPE: Strong and used for containers.
  2. Polyvinyl Chloride (PVC): Used in pipes, cables, and flooring.
  3. Polystyrene: Used in insulation and disposable cups.
  4. Nylon: A synthetic fiber used in textiles, ropes, and brushes.
  5. Teflon: Known for its non-stick properties, used in cookware.
  6. Rubber: Can be natural or synthetic, used in tires and seals.

6. Properties of Polymers

  1. Thermoplastics: Can be melted and reshaped, e.g., polyethylene, PVC.
  2. Thermosetting Polymers: Harden permanently after molding, e.g., Bakelite.
  3. Elasticity: Some polymers, like rubber, exhibit elasticity.
  4. Durability: Polymers are highly durable and resistant to chemicals.

7. Environmental Concerns

  1. Non-biodegradable polymers contribute to plastic pollution.
  2. Efforts are being made to develop biodegradable polymers (e.g., polylactic acid).
  3. Recycling and reuse can help reduce environmental impact.
Category
Polymers
Organic Chemistry
Chemistry