Education Journalist | Study Abroad Lead
Polymer can be defined as a large molecule or macromolecule, fundamentally made up of a number of smaller molecules. Natural polymers are those found in plants and animals; synthetic polymers are those manufactured by humans. All polymers are produced through the process of polymerization, in which their monomer building blocks react to form polymer chains, which are the 3-D networks that contain the polymer links. The kind of functional groups that are connected to the reactants determines the sort of polymerization mechanism that is used.
| Table of Content |
Key Terms: Polymers, Polymerization, Natural Polymers, Synthetic Polymers, Monomers, Tensile Strength, Density, Bakelite
What are Polymers?
[Click Here for Sample Questions]
A polymer refers to a large molecule (macromolecule) which is a combination of many subunits called monomers. Polymers can be classified into basically two types:
- Natural Polymers: Polymers found naturally in plants and animals.
- Synthetic Polymers: Polymers made by man artificially.
In addition to reflecting the monomer(s) from which the polymers are made, the repeating structural unit of most simple polymers also offers a clear method for representing these macromolecules in drawings.
Polymers
Read More: Difference Between Natural Polymers and Synthetic Polymers
Classification of Polymers
[Click Here for Previous Year's Questions]
Due to their complex forms, diverse behaviours, and wide range of applications, polymers cannot be categorised into a single group. So, using the following criteria, we may categorise polymers.
Classification of Polymers based on the Structure of the Monomer Chain
This category has the following classifications:
- Linear Polymers: This category includes polymers with a structure made up of long, straight chains. A linear polymer is an example of which is PVC, or polyvinyl chloride, which is primarily used for building pipes and electrical wires.
- Branched-Chain Polymers: They are defined as those in which a polymer's linear chains produce branches. For instance, Low-density polyethene.
- Cross-linked Polymers: Bifunctional and trifunctional monomers make up their structure. They have a stronger covalent bond in comparison to linear polymers. Examples in this group include melamine and bakelite.
Read More:
| Related Links | ||
|---|---|---|
| Neoprene | Amorphous and Crystalline Solids | Polyurethane Foam |
| Elastic Limit | Bulk Modulus | Shear Modulus |
| Polyamides | Derivations of Kinetic Energy | Sigma and Pi Bonds |
Classification of Polymers based on the Source of Availability
There are three types of polymers under this classification, namely,
- Natural Polymers: They are present in both plants and animals naturally. For instance, proteins, carbohydrates, cellulose, and rubber. Additionally, there are biopolymers, which are biodegradable polymers.
- Semi-Synthetic Polymers: These polymers are created through further chemical modification of naturally occurring polymers, for instance, cellulose nitrate and cellulose acetate as examples.
- Synthetic Polymers: These polymers are synthetic. The most popular synthetic polymer is plastic. It is utilised in many sectors and dairy products. Nylon-6, 6, polyethers, etc. are a few examples.
Other Ways to Classify Polymers
[Click Here for Sample Questions]
Here are some other ways in which we can classify polymers:
Classification Based on Monomers
- Homomer: This kind only contains one kind of monomer unit. Polyethene, for instance.
- Co-polymer or Heteropolymer: It is made up of various kinds of monomer units.
Classification Based on Molecular Forces
- Elastomers: These are solids that resemble rubber and have weak interfacial forces. Rubber, for example.
- Fibres: Strong, resilient, have high tensile strength and have strong forces of interaction. Nylon -6, for instance, has a 6.
- Thermoplastic Materials: These have intermediate attraction forces. For instance, polyvinyl chloride.
- Thermosetting Polymers: The material's mechanical characteristics are significantly enhanced by thermosetting polymers. Improved chemical and heat resistance is offered. Phenolics, epoxies, and silicones are a few examples.
Read More: Difference Between Thermoplastic and Thermosetting Plastic
Classification Based on Polymerization
- Repeated addition of monomers with double or triple bonds creates polymers through the process of addition polymerization. For example, polyethene, Teflon, and Polyvinyl chloride (PVC).
- The process of condensation polymerization entails several condensation reactions between two various bi- or tri-functional monomers. For example, Nylon -6, 6, perylene, and polyesters.
Classification of Polymers
Physical Properties of Polymers
[Click Here for Previous Year's Questions]
The major physical properties of polymers are as follows:
- Tensile Strength: A polymer's tensile strength refers to its ability to extend without breaking. This characteristic of polymers affects physical toughness and durability.
- High Melting and Boiling Points: These are two characteristics of polymers. Longer chains and stronger intermolecular interactions result in greater melting and boiling points.
- Hardness: Hard polymers are resistant to being penetrated by hard materials. They are employed in the production of building devices and can survive deterioration, scrapes, and use.
- Density: Based on the variations in densities, polymers are divided into high-density polymers and low-density polymers.
- Heat Capacity/Heat Conductivity: These properties determine how well a polymer insulates heat. The ability of a polymer to conduct heat depends on how rigid its molecular structure is.
- Thermal Expansion: This attribute measures how much a polymer expands or shrinks in response to heat or cold.
- Crystallinity: Because they are brittle, polymers with less crystallinity are more useful. The sort of organisation of polymeric chains determines this feature.
- Elasticity: Polymers with weakened intermolecular links are more elastic and may stretch farther.
- Resistance to Electric Current: The majority of polymers are poor electrical conductors. Nowadays, semiconductor gadgets use conductive polymers. The conjugated carbon-carbon double bonds give rise to their conductivity.
Read More: Difference between Conductors and Insulators
Chemical Properties of Polymers
[Click Here for Sample Questions]
Listed below are the major chemical properties of polymers:
- Bonding and Reactivity: The reactivity of polymers is determined by the strong covalent bond and various weak forces, including hydrogen bonding, between the particles. Polymers typically withstand chemicals because of their low reactivity.
- Interaction between the Reactive Groups: Each monomer's dipole determines the intermolecular forces between them. The hydrogen bond is created by the carbonyl group (amide group) found at the side chains of the monomers.
- The quality of polymers, like paints, is also influenced by their adhesion to surfaces, how they interact with coatings, and the outside environment.
- Biodegradability: Decomposers can cause polymers to break down. Synthetic polymers cannot biodegrade, although natural polymers can, such as rubber.
Factors Affecting Properties of a Polymer
[Click Here for Previous Year's Questions]
The properties of a polymer are influenced by a number of variables. Below is a discussion of a few of them:
- Temperature: Polymers are temperature-sensitive; as the temperature rises, so do their flexibility and compressive strength. As the temperature rises, the molecules' kinetic energy rises and their Young's modulus falls.
- Chain Length: It can be assumed that as a polymer's chain length rises, so does its strength.
- Branching: The mechanical strength of polymers rises along with branching. High-density polyethylene, for instance, has a low degree of crystallinity and poor mechanical characteristics. Polymers become stiffer, harder, and stronger as a result of branching.
- Cross-Linking: When polymer chains are widely connected together by potent covalent bonds, their strength rises and melting them becomes challenging.
- Nature of Side Groups: Polar side groups make polymeric chains more attracted to one another, strengthening them through hydrogen bonding and other attractive forces.
Read More: Decomposition
Uses of Polymers
[Click Here for Sample Questions]
Some of the important uses of polymers are as follows.
- Polypropene is used in a wide range of industries such as plastics, aircraft, construction, rope, toys, textiles, packaging, stationery, etc.
- Polystyrene is one of the most basic forms of plastic and is used to make bottles, toys, containers, trays, disposable glasses and plates, etc and it also acts as an insulator.
- Polyvinyl chloride is used in manufacturing sewage pipes and is also used as an insulator in electric cables. It also finds its usage in clothing and furniture and is used for the construction of doors and windows too.
- Urea-formaldehyde resins are used in the manufacturing of adhesives, moulds, laminated sheets, etc.
- Glyptal is brought into use for manufacturing paints, coatings, and lacquers.
- Bakelite is used in making various appliances and household items such as electrical switches, kitchen products, toys, jewellery, firearms, insulators, etc.
Uses of Polystyrene
Things to Remember
- Polymers are chemical compounds with large molecules that frequently resemble long chains and are composed of seemingly limitless interconnecting link series.
- Chain length, side group content, branching, and cross-linking all affect a polymer's physical characteristics including strength and flexibility.
- Polymers can be classified on numerous bases such as on the basis of their source of availability, the structure of the monomer chain, polymerization and molecular forces.
- Both crystalline (more ordered, crystal-like) and amorphous (less ordered) regions can be found in synthetic polymers.
- The degree of crystallinity, which ranges from zero for an entirely non-crystalline polymer to one for an idealised wholly crystalline polymer, is what defines a polymer's crystallinity.
Read More: Polypropylene
Important PYQs Based On Polymers
- Which Of The Following Is Not A Synthetic Fibre
- Which Of The Following Polymers Is Prepared By Con
- Which Of The Following Structures Represents Neopr
- Which One Of The Following Is A Chain Growth Polym
- Which One Of The Following Is An Example For Biode
- Which One Of The Following Monomers Form Biodegrad
- Which One Of The Following Sets Forms The Biodegra
- Zeigler Natta Catalyst Is Used To Prepare
- Acrilan Is A Hard Horny And A High Melting Materia
- Formaldehyde Polymerizes To Form Glucose According
- Which One Of The Following Is Not Correctly Matche
- Which Of The Following Has Ester Linkage
- Which Of The Following Is A Condensation Polymer
- Which Of The Following Is A Example Of Co Polymer
- Which Of The Following Is Not A Semi Synthetic Pol
- Which Of The Following Is Not A Synthetic Polymer
- Which Of The Following Is Not An Example Of Additi
- Which Of The Following Is Not An Example Of Rubber
- Which Of The Following Is Not True For Thermoplast
- Which Of The Following Represents The Example Of H
Sample Questions
Ques. Describe polymers and their characteristics. (3 Marks)
Ans. A polymer is any class of natural or manmade substance made of very massive molecules, known as macromolecules, which are collections of monomers, or simpler chemical building blocks. Depending on how they are structured, polymers can have various qualities. For instance, entanglement occurs in polymers with relatively high molecular weight and long chain lengths, and the mobility and flexibility of polymer chains are facilitated by a deficiency of covalent intermolecular connections.
Ques. What are the polymers' physical characteristics? Which three characteristics do polymers have? (3 Marks)
Ans. Tensile strength, hardness, heat conductivity, electrical conductivity, refractive index, melting point, boiling point, elasticity, crystallinity, permeability, etc. are a few of the physical characteristics of polymers.
The mechanical strength, elasticity, and thermal expansion of polymers are their three key characteristics.
Ques. What are the applications of polymer? (3 Marks)
Ans. Polymers are utilised in practically every aspect of life, including clothes, the production of plastic goods, industrial applications, medical and dental treatments, the production of electrically conductive objects, the manufacture of cooking utensils and their handles, and many other things.
Ques. What characteristics do natural polymers have? (2 Marks)
Ans. Natural polymers are stable, biocompatible, non-toxic, and degradable. Rubber, proteins, and carbohydrates (polysaccharides) are a few examples of natural polymers (polyamides).
Ques. What are the polymers' chemical characteristics? (4 Marks)
Ans. The bonding and reactivity of polymers, as well as other weak forces like hydrogen bonding between the particles of polymers that govern its reactivity, are all examples of the chemical features of polymers. Due to their low reactivity, polymers typically withstand chemicals.
The hydrogen bond is created as a result of functional side chain elements like the amide and carbonyl groups of the monomers. Like paints, the quality of polymers depends on how well they adhere to surfaces, how well they interact with coatings, and how the outside environment influences them. Biodegradability refers to a material's capacity to break down through the activity of decomposers.
Ques. How do thermosetting polymers work? (3 Marks)
Ans. Thermoplastics, such as polystyrene and polyethylene, can be repeatedly moulded. So, a cup made of foamed polystyrene may be heated while also being reshaped into, let's say, a dish. The polymer structure connected to thermoplastics separates individual molecules from one another and allows them to flow past one another. The molecules might be linear or branching in structure, and they can have any molecular weight. However, the crucial characteristic is concomitant mobility and separability.
Ques. How do thermoplastics work? (3 Marks)
Ans. Long-chain polymers called thermoplastic polymers are held together by Van der Waal forces, which act between molecules. When heated, these polymers become soft (thick fluid-like), and after cooling, they solidify to create a solid mass. They are free of cross bonds and are easily moulded using heat and moulds. Polystyrene or PVC are frequent examples (which are used in making pipes).
Ques. What are high-temperature polymers, and why are they special? (3 Marks)
Ans. These polymers maintain their stability at elevated temperatures. Due to their large molecular weight, they do not melt at very high temperatures. They are utilised in the healthcare sector to create heat- and shock-resistant products as well as sterilisation equipment.
It's a type of polymer that softens above a certain temperature, allowing for moulding, and then hardens after cooling. Due to its ease of shaping into different shapes, it has a wide range of applications.
Ques. What are biodegradable polymers? Give examples. (2 Marks)
Ans. Functional groups are present in these polymers that are also present in natural polymers. Example: Poly (hydroxybutyrate)-co-hydroxy valerate (PHBV). Bacterial activity has the potential to degrade this.
Also check:
Comments