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Revision: Polymers Chemistry HSC Science (General) 12th Standard Board Exam Maharashtra State Board

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Definitions [2]

Define rubber.

Polymers which are elastic in nature are called rubber.

Answer the following in one sentence.

Define the term: Vulcanization

The process by which a network of cross-links is introduced into an elastomer is called vulcanization.

Key Points

Key Points: Classification of Polymers> Based on Source or Origin
  • Polymers are classified based on their source or origin into three types: natural, semi-synthetic, and synthetic polymers.
  • Natural polymers are obtained from plants and animals, such as cellulose, starch, proteins, cotton, and silk.
  • Semi-synthetic polymers are chemically modified forms of natural polymers, e.g., cellulose acetate and cellulose nitrate (rayon).
  • Synthetic polymers are man-made and prepared in laboratories by polymerisation, such as nylon, polythene, Teflon, and Bakelite.
  • Synthetic polymers are further used to make fibres, rubbers, and plastics, which have wide industrial applications.
Key Points: Some Important Polymers
Polymer Monomer(s) Uses
Natural Rubber (Polyisoprene) Isoprene (2-methyl-1,3-butadiene) Exhibits elastic property
Neoprene Chloroprene (2-chloro-1,3-butadiene) Conveyer belts
Buna-S 1,3-Butadiene + Styrene Bubblegums, tyres
Buna-N 1,3-Butadiene + Acrylonitrile Rubber belts, shoe soles, O-rings, gaskets
Polypropene Propene Ropes, toys, pipes, fibres
Polystyrene Styrene Insulator, wrapping material, toys, radio & TV cabinets
PVC Vinyl chloride Rain coats, handbags, vinyl flooring, water pipes
Glyptal Ethylene glycol + Phthalic acid Paints and lacquers
Bakelite Phenol + Formaldehyde Combs, phonograph records, electrical switches, wooden planks
Nylon 6,6 Adipic acid + Hexamethylenediamine Fabrics, ropes, tyre cords
Nylon 6 ε-Caprolactam Fabrics, ropes
Terylene / Dacron Ethylene glycol + Terephthalic acid Fibres, safety belts, tents
Melamine-formaldehyde Melamine + Formaldehyde Unbreakable crockery
Urea-formaldehyde resin Urea + Formaldehyde Unbreakable cups, laminated sheets
Key Points: Classification of Polymers> Based on Biodegradability

Polymers are classified as biodegradable or non-biodegradable based on their biodegradability.

1. Biodegradable Polymers

  • Meaning: Polymers that decompose by microorganisms or enzymes.
  • Nature: Environment-friendly, as they break down naturally.
  • Examples: PHBV, Nylon-2–Nylon-6.
  • Special point: PHBV is a copolymer used in packaging, medical devices, and drug delivery.
  • Use: Helps reduce environmental pollution.

2. Non-Biodegradable Polymers

  • Meaning: Polymers that do not decompose by microorganisms.
  • Nature: Persist in the environment for a long time.
  • Examples: Polythene (LDPE, HDPE), Teflon, Nylon-6,6, PAN.
  • Use: Widely used in plastics, fibres, containers, insulation, etc.
  • Disadvantage: Causes environmental pollution due to slow decomposition.

Important Questions [41]

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