| |
|
|
| |
| Introduction to Polymer |
- There are various items around us that are made up of polymers such as protein, starch, polyethylene and nylon.
- The basic unit of a polymer is called a monomer.
- The reaction of monomer fusion to produce a polymer is called the polymerisation reaction.
- Polymers can be classified into several groups based on the source of the polymer, the way the polymer is produced and the characteristics of the resulting polymer.
|
|
| |
| Definition of Polymer |
| A long chain molecule that is made from a combination of many repeating basic units. |
|
| |
| Source of Polymer |
- Polymers consist of natural polymers or synthetic polymers.
- Natural polymers are polymers that are produced naturally and can be obtained from the environment.
- Examples of natural polymers include starch, protein and cotton.
- Synthetic polymers are produced by humans through chemical reactions in laboratories or in factories.
- Nylon, polyethylene, polystyrene and polyvinyl chloride (PVC) are among the examples of synthetic polymers produced in the industrial sector.
- Starch is a natural polymer made from glucose.
- Meat is one of the sources of protein. Proteins are made from amino acids that are a type of monomer.
|
|
| |
 |
| |
| Source of Polymer |
Polymer |
Monomer |
| Natural |
Starch |
Glucose |
| Natural |
Cellulose |
Glucose |
| Natural |
Protein |
Amino acid |
| Natural |
Natural rubber |
Isoprene |
| Synthetic |
Polystyrene |
Styrene |
| Synthetic |
Polypropene |
Propene |
| Synthetic |
Polyvinyl chloride |
Vinyl chloride |
|
| |
 |
| |
| Types of Polymer |
- The structure of thermoplastic polymers is as shown below:
- Characteristic of thermoplastic polymers:
- Can be molded repeatedly after being heated and can be recycled.
- When heated, the thermoplastic polymer melts and hardens when cooled.
- Example:
- Polyethane, polyvinyl chloride (PVC), nylon..
|
- Th structure of thermosetting polymers is as shown below:
- Characteristic of thermosetting polymers:
- Cannot be remoulded after heating.
- Normally disintegrate or burn upon heating and cannot be recycled.
- Example:
|
- The structure of elastomer polymers is as shown below:
- Characteristic of elastomer polymers:
- Can be stretched and can return to their original shape when released.
- Possess high elasticity properties.
- Example: Polyurethane, styrene-butadiene rubber (SBR).
|
|
| |
| Polymerisation Reaction |
- Polymerisation reactions are divided into two types, namely addition polymerisation and condensation polymerisation.
- Addition polymerisation occurs when the monomer has a double covalent bond between the carbons, C = C reacting with each other.
|
|
| |
| Types of Polymerisation Reaction |
- Addition polymerisation occurs when monomers that have double covalent bonds between two carbon atoms, C C react with one another.
- Examples of polymers that are produced through addition polymerisations are shown in table below with their respective monomers.
| Monomer |
Polymer |
Charateristic |
Use |
| Ethene |
Polyethene |
Durable and strong. |
Plastic bags, plastic bottles and plastic packaging. |
| Propene |
Polypropene |
Durable. |
Toys and textile. |
| Chloroethene (vinyl chloride) |
Polychloroethene (Polyvinyl chloride, PVC) |
Strong and hard. |
Water pipes and electrical insulators. |
| Styrene |
Polystyrene |
Light and heat insulator. |
Heat insulators and food packaging. |
- During the reaction, double bonds are "opened" and monomers are "added" to the molecular chain to produce a polymer.
- The following diagram shows the polymerisation of ethene to produce polyethene.
| Addition Polymerisation of Ethene |
 |
|
| Condensation Polymerisation |
- Condensation polymerisation involves at least two different types of monomers.
- The monomers involved have two functional groups involved in the polymerization reaction.
- The result of condensation polymerization is a polymer and another product such as water or HCl molecules.
- The condensation polymerisation to produce terylene and nylon is as shown below:
| Condensation Polymerisation to Produce Terylene |
 |
| Condensation Polymerisation to Produce Nylon |
 |
|
|
| |
 |
| |
| Uses of Synthetic Polymers |
- Various medical and laboratory devices are made from polypropene.
- The most widespread use of polyethylene is as a plastic bag.
- Nylon produces yarn that is important for the textile industry.
- Acrylic polymer coatings are used to produce waterproof roofs.
|
|
| |
| Polymers and Environment |
- The nature of some polymers which are durable and take a very long time to decompose causes serious pollution problems.
- Pollution in the oceans causes many living things to die and microplastics to enter the food chain.
- Garbage disposal centers are filled with non-biodegradable plastic bags that will affect the environment.
- Recycling is the easiest way for consumers to ensure synthetic polymers do not end up in landfills.
- The introduction of degradable or decomposable polymers especially for plastic products allows pollution to be reduced.
- Additives are included to allow plastic items to decompose naturally by bacteria (biodegradation) or decompose by light (photodegradation).
- Plastic items will decompose faster and can reduce the problem of dumping plastic items at landfills as well as safer for wild animals.
|
|
| |
