Question:

How can you differentiate between addition and condensation polymerisation?

Answer:

1. Addition polymerization is a process in which monomers are joined together to form a polymer chain without the formation of by-products. The monomers are joined together by a covalent bond.

2. Condensation polymerization is a process in which two molecules react to form a larger molecule, with the formation of a by-product. The molecules are joined together by a chemical bond such as an ester or an amide bond.

3. One way to differentiate between addition and condensation polymerization is to look at the type of bond formed. In addition polymerization, a covalent bond is formed between the monomers, while in condensation polymerization, an ester or amide bond is formed between the molecules.

4. Another way to differentiate between the two is to look at the by-products formed. In addition polymerization, no by-products are formed, while in condensation polymerization, a by-product is formed.

Question:

How is dacron obtained from ethylene glycol and terephthalic acid ?

Answer:

Step 1: Combine ethylene glycol and terephthalic acid in a chemical reactor.

Step 2: Heat the mixture to a temperature of approximately 220°C.

Step 3: Allow the mixture to react for a period of time until the polyester polymer is formed.

Step 4: Cool the mixture to room temperature.

Step 5: Collect the polyester polymer, which is now dacron.

Question:

How do you explain the functionality of a monomer?

Answer:

Step 1: A monomer is a small molecule that can be joined with other molecules to form a larger molecule, known as a polymer.

Step 2: Monomers are typically made up of atoms of carbon, hydrogen, oxygen, and nitrogen, although other elements can also be present.

Step 3: Monomers can be joined together by a process known as polymerization, in which the monomers bond together to form a single, larger molecule.

Step 4: The type of monomer and the number of monomers in the polymer determines the properties and characteristics of the polymer. For example, some polymers are strong and durable, while others are more flexible and can be used in a variety of applications.

Question:

Define the term polymerisation.

Answer:

Step 1: Polymerisation is a process in which large molecules called polymers are formed by the combination of many smaller molecules called monomers.

Step 2: Polymerisation is a chemical reaction in which multiple monomers are linked together to form a larger molecule.

Step 3: Polymerisation can occur naturally in living organisms or through synthetic processes.

Step 4: The products of polymerisation can be used for a variety of purposes, such as the production of plastics, rubbers, and adhesives.

Question:

What are natural and synthetic polymers? Give two examples of each type.

Answer:

1. Natural polymers are polymers that occur naturally in nature, while synthetic polymers are man-made polymers.

2. Examples of natural polymers include proteins and cellulose.

3. Examples of synthetic polymers include nylon and polystyrene.

Question:

Write the name and structure of one of the common initiators used in free radical addition polymerisation.

Answer:

Name: Azobisisobutyronitrile (AIBN)

Structure: C6H12N2

Question:

Discuss the main purpose of vulcanisation of rubber.

Answer:

1. Start by defining vulcanisation of rubber, which is a process of treating rubber to make it stronger, more durable, and more resistant to heat and chemical damage.

2. Explain that the main purpose of vulcanisation is to improve the properties of rubber, making it more suitable for use in a variety of applications.

3. Discuss how vulcanisation increases the strength and durability of rubber, making it more resistant to wear and tear, and better able to withstand high temperatures and harsh chemicals.

4. Explain that vulcanisation also increases the elasticity of rubber, making it more flexible and easier to manipulate.

5. Finally, discuss how vulcanisation makes rubber more resistant to oxidation and other forms of degradation, making it a more reliable material for a wide range of uses.

Question:

Define thermoplastics and thermosetting polymers with two examples of each.

Answer:

Thermoplastics: Thermoplastics are polymers that can be softened and re-shaped multiple times when heated. Examples include polyethylene and polypropylene.

Thermosetting polymers: Thermosetting polymers are polymers that become permanently hard and rigid when heated. Examples include phenolic resins and polyurethanes.

Question:

Explain the term copolymerisation and give two examples.

Answer:

1. Copolymerisation is a type of polymerisation process in which two or more different monomers react to form a copolymer.

2. Examples of copolymerisation include: a) Polyethylene terephthalate (PET) which is formed from a reaction between ethylene glycol and terephthalic acid. b) Nylon 6,6 which is formed from a reaction between hexamethylene diamine and adipic acid.

Question:

Explain the terms polymer and monomer.

Answer:

Step 1: Polymer is a large molecule composed of repeating smaller units called monomers.

Step 2: Monomers are molecules that can be bonded together to form polymers. They are the basic building blocks of polymers and can be organic or inorganic. Examples of monomers include glucose, amino acids, and nucleotides.

Question:

Distinguish between the terms homopolymer and copolymer and give an example of each.

Answer:

1. Homopolymer: A homopolymer is a polymer made up of a single type of monomer. Example: Polyethylene (made up of only ethylene monomers).

2. Copolymer: A copolymer is a polymer made up of two or more different types of monomers. Example: Polyethylene terephthalate (made up of ethylene and terephthalate monomers).

Question:

Define the term polymerisation

Answer:

Step 1: Understand the term ‘polymerisation’: Polymerisation is a process in which two or more small molecules (monomers) combine to form a larger molecule (polymer).

Step 2: Identify the components of the process: Polymerisation involves the combination of two or more monomers to form a polymer.

Step 3: Explain the process of polymerisation: The process of polymerisation involves the joining of monomers through chemical bonds to form a polymer. This process is known as polymerisation or polymerization. The resulting polymer has a different structure and properties than the individual monomers.

Question:

How does the presence of double bonds in rubber molecules influence their structure and reactivity?

Answer:

1. Double bonds in rubber molecules affect the structure of the molecules by increasing the number of bonds between the atoms and increasing the flexibility of the molecules.

2. Double bonds also increase the reactivity of rubber molecules, as they are more susceptible to chemical reactions due to their increased flexibility. This increased reactivity can be used to create different types of rubber with different properties.

Question:

Write the monomers used for getting the following polymers. (i) Polyvinyl chloride (ii) Teflon (iii) Bakelite

Answer:

(i) Monomers used for Polyvinyl chloride: Vinyl Chloride (VC)

(ii) Monomers used for Teflon: Tetrafluoroethylene (TFE)

(iii) Monomers used for Bakelite: Phenol and Formaldehyde

Question:

Write the names and structures of the monomers of the following polymers: (i) Buna-S (ii) Buna-N (iii) Dacron (iv) Neoprene

Answer:

(i) Buna-S: Monomer name - Butadiene; Structure - CH2=CH-CH=CH2

(ii) Buna-N: Monomer name - Acrylonitrile; Structure - CH2=CH-CN

(iii) Dacron: Monomer name - Polyethylene terephthalate; Structure - (C10H8O4)n

(iv) Neoprene: Monomer name - Chloroprene; Structure - CH2=CCl-CH=CH2

Question:

What are the monomeric repeating units of Nylon-6 and Nylon-6,6?

Answer:

Nylon-6:

1. Nylon-6 is a polyamide made from a single monomeric repeating unit, which is the monomer caprolactam.

Nylon-6,6:

1. Nylon-6,6 is a polyamide made from two monomeric repeating units, which are the monomers adipic acid and hexamethylene diamine.

Question:

In which classes, the polymers are classified on the basis of molecular forces?

Answer:

1. Polymers are classified into three main categories on the basis of molecular forces: covalent, ionic, and metallic.

2. Covalent polymers are formed when atoms of the same element share electrons, forming strong covalent bonds. Examples include polyethylene and polypropylene.

3. Ionic polymers are formed when atoms of different elements exchange electrons, forming ionic bonds. Examples include polyvinyl chloride and polyvinylidene chloride.

4. Metallic polymers are formed when atoms of different elements share electrons, forming metallic bonds. Examples include polytetrafluoroethylene and polyethylene terephthalate.

Question:

What is a biodegradable polymer ? Give an example of a biodegradable aliphatic polyester.

Answer:

1. A biodegradable polymer is a type of polymer that can be broken down by microorganisms into its original components, such as carbon dioxide, water, and biomass.

2. An example of a biodegradable aliphatic polyester is polylactic acid (PLA). PLA is a plastic-like material made from renewable resources, such as corn starch or sugar cane. It is biodegradable, recyclable, and compostable.

Question:

Write the free radical mechanism for the polymerisation of ethene.

Answer:

1. Initiation: Ethene molecules are broken down into free radicals by heat, light, or a catalyst.

2. Propagation: The free radicals react with other ethene molecules to form a carbon-carbon bond, creating a new radical in the process.

3. Termination: The reaction is terminated when two radicals react with each other, forming a non-radical product.