Introduction of Polymers
Modern life cannot be imagined without polymers. In order to manage our daily life in a simple and easy way, the importance of polymers is immense. If we take a closer look, we can see that most of the items used in our daily life are made of polymers. For example Brush, plastic cups, plastic bags, buckets, toys, synthetic cloth, tyres, electrical insulating materials, etc. Even the proteins in our body are polymers. All these materials are made with different types of polymers. So, in this chapter, we will be discussing different types of polymers.
What are Polymers?
• A Polymer is a combination of many repeating subunits.
• The polymers are giant molecules with high molecular masses (103 -107u)
• These repeating subunits are called ‘monomers’.
• The word ‘polymer’ is derived from two Greek words, Poly – means ‘many’ and ‘Mer’ – means ‘unit or part’.
• For example the monomer ethylene gets linked with many other ethylene molecules to form polyethylene, or a large number of vinyl chloride molecules combine to form polyvinyl chloride.
Common classifications of polymers
• Based on some special features (such as source, and structure) the following are some of the common classifications of polymers.
1. Classification Based on Source.
2. Classification Based on Structure of Polymers
3. Classification Based on Mode of Polymerisation
4. Classification Based on Molecular Forces
Classification of Polymers Based on Source
• there are three subcategories-
- 1. Natural polymers
- 2. Semi-synthetic polymers
- 3. Synthetic polymers
- Natural polymers are the most common type of polymers.
- These are found in humans and animals.
- Examples – Resins and Rubber, Starch and Cellulose (found in Plants), Proteins (found in Animals).
- Semi-Synthetic polymers are produced artificially in labs by the modification of natural polymers.
- Example – Cellulose acetate (rayon) and cellulose nitrate, both are Cellulose derivatives
- Synthetic polymers are artificially produced by humans.
- Due to high demand, these are produced commercially by industries.
- Example: – Plastic (polythene), Nylon 6, 6, Synthetic rubbers (Buna – S)
Classification of Polymers based on Structure of Polymers
• Polymers based on Structure are subdivided into three categories:
- Linear polymers
- Branched-chain polymers
- Cross-linked or Network polymers
- Monomers are united together to form a long straight chain.
- High melting and boiling points, high density and high tensile strength. (Due to well-packed structure)
- Example: – High-density polythene, Polyvinyl chloride (PVC), Nylon.
- This type of polymer is used to make bottles, Buckets, and PVC pipes.
- Linear chain which has branches.
- Low density, low melting points.
- They are not well packed due to the formation of branches.
- Low melting and boiling points, low density, and low tensile strength. (Due to the formation of branches, they are loosely tied)
- Example: – Low-density polyethylene (LDPE).
- Low-density polyethylene is used to manufacture plastic bags, dispensing bottles, tubing, and wash bottles.
Cross-linked or Network polymers
- Network polymer is formed by bi-functional and tri-functional monomers.
- The monomers are linked together by strong covalent bonds.
- A three-dimensional network formed by the monomers of the cross-linked polymers.
- Example: – Bakelite, Melamine.
- Bakelite is widely used in the manufacturing of electrical insulating materials.
- Melamine is primarily used in the manufacturing of floor tile, kitchenware, and fabrics.
Classification of Polymers based on the Mode of Polymerisation
- On the basis of the mode of polymerization, the polymers can also be classified into two subgroups.
- Addition polymers
- Condensation polymers
- This polymer is formed by the Simply repeated addition of monomeric units. (Molecules of single monomer)
- In addition polymerization reaction never produced any by-products (e.g water)
- The monomeric unit is unsaturated or possesses double bonds.
- Additional polymer is non-biodegradable and resistant to acids.
- Example:- Polythene, polypropene.
- This polymer is formed by the Simply repeated addition of two different monomeric units. (Molecule of two different monomers)
- The condensation reaction produced by-products (usually water)
- The monomeric unit contains reactive functional groups that attend to the molecules.
- Carboxylic acid and alcohol are the two functional groups.
- Biodegradable and can be hydrolyzed by acids.
- Example:- nylon 6, Terylene (Dacron), Nylon 6, 6
Classification of polymers based on Molecular Force
• Mechanical properties of polymers depend on the intermolecular force of the polymer.
• Some of the mechanical properties are elasticity, toughness, tensile strength
• These mechanical properties are governed by intermolecular forces like…..
1. Van der Waals forces
2. Hydrogen bonds are present in the polymer.
• Based on the intermolecular forces present in the polymer, polymers are divided into four subclasses. they are _
3. Thermoplastic polymers
4. Thermosetting polymers
Elastomers or Rubber
- Weakest intermolecular force (Van der Waals force) of attraction between molecules.
- Due to this weakest force, the polymer can be stretched by applying some force and when the force is released the polymer returns its original shape.
- Example: – Buna-S, Buna-N, Neoprene.
- Strong molecular forces (like hydrogen bonding).
- High tensile strength and high modulus.
- Example: – Polyamides (nylon 6, 6), Polyesters (Terylene)
- Long chain linear or slightly branched molecules.
- It becomes soft on heating and hard on cooling.
- Its intermolecular forces of attraction are intermediate between elastomers and fibers.
- Weak intermolecular forces of attraction due to Weak Vander Waals force
- The thermoplastic polymer is prepared by the addition polymerization reaction.
- Low molecular weights.
- Soluble in organic solvents.
- Example: – Polystyrene, Polythene, Polyvinyls.
- Heavily branched, cross-linked polymer.
- Also known as thermoset
- Also called rigid temperature polymers.
- The thermosetting polymer is prepared by the condensation polymerization reaction.
- Cannot be softened by heating.
- The strong intermolecular force of attraction is due to strong covalent bonds.
- These are hard, strong, more brittle, and cannot be reused,
- Thermosetting polymers don’t soften on heating.
- High molecular weights.
- Insoluble in organic solvents.
- Examples: – Polyester, Epoxy-resin, Urea-formaldehyde, and Melamine.
Classification of Polymers Infographics
List of Polymers, Monomers, and Uses
|Polypropylene||• Propane||• Manufacturing of Ropes, Toys, Pipes, Fibres|
|Polystyrene||• Styrene||• Insulator|
• Wrapping material
• Manufacture of Toys
• Manufacture of Radio and
/ Dacron or terylene
|• Ethylene glycol|
• Terephthalic acid
|• Used in blending with cotton and wool fibres|
• Glass reinforcing materials in safety helmets
| Polyvinyl chloride|
|• Vinyl chloride||• Manufacture of rain coats,|
hand bags, vinyl flooring, water pipes
|Glyptal.||• Ethylene glycol|
• Phthalic acid
|• Manufacture of Paints and Lacquers|
|Urea-formaldehyde Resin||• Urea|
|• For making Unbreakable cups and Laminated Sheets.|
|• Making combs|
• Electrical switches
• Handles of Utensils
• Computer discs
| Poly β-hydroxybutyrate|
– co-β-hydroxy valerate
|• 3-hydroxybutanoic acid|
• 3 – hydroxypentanoic acid
|• Used in the packaging of|
|Buna – N||•1, 3 – butadiene|
|• Used in making oil seals, Tank lining|
|Neoprene||• Chloroprene.||• Used for manufacturing Conveyor belts|
Gaskets and Hoses.
|• Manufacturing of unbreakable crockery|
|• Tetrafluoroethene||• Used in making oil seals and|
gaskets , non–stick surface coated utensils
|• Acrylonitrile||• Making commercial fibres as orlon or acrilan|
|Nylon 6||• Caprolactum||• Manufacture of tyre cords, fabrics, and ropes|
|Nylon 6,6||• Hexamethylenediamine|
• Adipic acid
|• Used in making sheets, bristles|
for brushes and in the textile industry
Types of Polymers: Previous Year Questions
Q1. PVC is obtained by the polymerization of? [SSC Section Officer (Audit) 2005]
Answer: Vinyl chloride
Q2. The Polymerization of which, is used in the polyethylene manufacturing industry? [SSC Section Officer (Commercial Audit) 2005]
Q3. A polymeric substance used to make parachute is? [SSC Tax Assistant (Income Tax & Central Excise) 2005]
Q4. The Polythene is a polymer of? [SSC Section Officer (Audit) 2006]
Q5. The polymer used in making plastic crockery is? [SSC CGL Prelim 2007]
Q6. The name of the plastic polymer from which combs, toys, bowls etc., can be made, is? [SSC Combined Matric Level (PRE) 2002]
Q7. Natural rubber is the polymer of [SSC MTS 2011]
Q8. Bakelite is a copolymer of Phenol and? [SSC Stenographer Grade ‘C’ & ‘D’ 2011]
Frequently Asked Questions (FAQ)
Answer: Nylon 66
Answer: Dialkyl dichloro silane
Answer: Terephthalic acid
Answer: Polyamide polymer
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