Bakelite: Structure, Introduction, Preparation, Properties, Uses and Frequently Asked Questions

When we see a child in our family or neighbourhood playing with toys it reminds us of the time when we use to do the same thing during our childhood days. But our toys used to break easily and have to weight for a new toy for some time to play with. But t is not so now. They are almost unbreakable and have you ever thought about the materials from which these toys are now made? 

Probable you will guess it is plastic. But let me tell you that you are only partially correct in your answer. It is known as bakelite. 

Between 1907 and 1909, Belgian chemist Leo Baekeland produced Bakelite, the first synthetic moulding plastic. Let's have a tour of this article to learn more about bakelite.

Table of content

• Introduction of bakelite
• Preparation of bakelite
• Properties of bakelite
• Uses of bakelite
• Practice problems
• Frequently asked questions-FAQs

Introduction of bakelite

• It is a condensation polymer made from the monomers of phenol and formaldehyde.
• Polyoxy Benzyl methylene glycol anhydride is another name for bakelite.
• It is one of the first polymers created by humans. It's also an example of a thermosetting plastic because once it is heated or moulded it cannot be reshaped or remoulded again. 
• Phenol reacts with formaldehyde to give a polymer the nature of which depends on the concentration of phenol, formaldehyde, acidic or basic nature of the medium, catalyst present and so on.
• When phenol is present in excess in an acidic medium, the condensation reaction produces a product which is acidic in nature called novolac. 
• The amount of formaldehyde in the combination is more than the amount of phenol in the mixture, and the reaction takes place in a basic medium the product will be a polymer called Resol. The reaction is extremely exothermic.

Preparation of Bakelite

The preparation of Bakelite is done in the following steps:

• Ortho and para hydroxy benzyl alcohols are formed when phenol and formaldehyde react.
• Novolac is created by removing a water molecule during the polymerization process of hydroxy benzyl alcohol, formed from phenol and formaldehyde in an acid medium with HCl or ZnCl₂..
• Novoloac on further heating in the presence of a crosslinking catalyst hexamethylenetetramine (in short known as HEXA) produces the liquid cross condensed polymer Bakelite
• The liquid bakelite is mixed with a filler and moulded to the required product.

Properties of bakelite

• Bakelite is the commercial name for phenol-formaldehyde resin which comes in a wide range of vibrant colours and can be moulded quickly.
• When heated, it is pliable and liquefiable, but once cooled, it becomes permanently rigid and is referred to as thermosetting plastic.
• It is very resistant to electrical, thermal, and chemical activity. As a result, electronic devices, switches, and car parts are manufactured using bakelite.
• Bakelite is also classified as a thermosetting plastic (i.e once it is moulded it becomes permanently rigid and cannot be remoulded again by heating.

Uses of bakelite

• Bakelite is used in the manufacture of a variety of products, including utensil handles, bangles, and vehicle parts.
• It may be dyed into a variety of colours, allowing it to be employed in the creation of vivid and appealing products.
• Bakelite is a good insulator that is used in the manufacture of non-conducting parts of radio and electric devices such as sockets, wire insulation, switches and automobile distribution caps etc. 
• It is used in the manufacture of clocks, buttons, washing machines, toys, kitchenware, and other items. 

Practice problems

Q1. Which of the following statement is incorrect for bakelite. 

1. It is an example of an addition polymer. 
2. It is used in the manufacture of products like switches, clocks, buttons etc
3. It is referred to as thermosetting plastic.
4. It is prepared by heating novolac in the presence of crosslinking catalysts. 

Answer: (A)

Solution: Bakelite is an example of a condensation polymer which is prepared from heating novolac in the presence of cross-linking catalysts. It is sometimes also referred to as thermosetting polymers because on heating it gets converted into infusible mass and cannot be remoulded. Therefore, option (A) is incorrect. 

Q2. Select the correct option of the monomer used in the preparation of bakelite. 

1. Chloroprene
2. Ethylene glycol and terephthalic acid
3. Caprolactam
4. Phenol and formaldehyde

Answer: (D)

Solution: The monomer used in the preparation of bakelite is phenol and formaldehyde. Whereas chloroprene is the monomer of neoprene, ethylene glycol and terephthalic acid together form terylene, and caprolactam is the monomer of nylon-6 respectively. Therefore, option (D) is correct.

Q3. On the basis of intermolecular strength, bakelite is classified into which of the following types of polymer? 

1. Thermo plastics
2. Thermosetting plastics
3. Elastomers
4. Fibres

Answer: (B)

Solution: Bakelite is an example of thermosetting plastic because once it is heated it converts into infusible mass and cannot be remoulded or reshaped on heating. 

• Thermoplastic on the other hand is a polymer which has intermolecular force between elastomers and fibres. 
• Elastomers are referred to as a polymer which can stretch due to weak van der Waal force of attraction and can regain their shape once the force is removed. 
• Fibers are referred to as a polymer which has high tensile strength and less elastic nature due to comparatively strong force of attraction like hydrogen bonding. 

Q4. Which of the following polymers have the same monomers? 

1. Nylon-6 and Nylon-6,6
2. Bakelite and terylene
3. Bakelite and Novolac
4. Natural rubber and Buna-S

Answer: 

Solution: Bakelite and novolac is formed from formaldehyde and phenol monomers. Whereas the monomer of nylon-6 is caprolactam, the monomer of nylon-6,6 is adipic acid and hexamethylene diamine, the monomer of terylene is ethylene glycol and terephthalic acid, the monomer of natural rubber is isoprene and the monomer of Buna-S is 1,3 butadiene and styrene respectively. Therefore option (C) is correct. 

Frequently asked questions-FAQs

Question 1. Why bakelite is classified as an example of thermosetting plastics?
Answer: Thermosetting plastic is a type of polymer which is heavily branched, crosslinked and forms a 3-D network structure like bakelite. It exhibits the property in that when it is heated it converts into infusible mass and cannot be remoulded or reused. 

Question 2. Why bakelite is used in the manufacturing of electrical appliances? 
Answer: Bakelite exhibits some important properties which include resistance to electricity, heat, and other chemical reactions and is therefore it is found useful in manufacturing electrical appliances like switches, sockets, radio parts etc. 

Question 3. What is the difference between step-growth polymer and chain-growth polymerization?
Answer: Step-growth polymer is also known as condensation polymer. This type of polymerisation takes place in those compounds in which monomers have a bi-functional or tri-functional group and is polymerised by the elimination of small molecules like ammonia, water, hydrogen etc. Her oligomers are formed first, which later form condensation products.

In chain-growth polymerization, chain polymers are formed from the beginning.

Question 4. What is the difference between thermoplastic and thermosetting plastic? 
Answer: The difference between thermoplastic and thermosetting plastics are: 

Question 5. What is novolac and how it is different from bakelite? 
Answer: Novolac is the polymer which is a linear condensation polymer of phenol and formaldehyde. Whereas, Bakelite is an example of a cross-linked condensation polymer which is prepared from heating novolac in the presence of cross-linking catalysts. It is sometimes also referred to as thermosetting polymers

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