Tag: Bakelite

Introduction

The shortest form of polymers is called monomers. Depending on their characteristics, preparation process, and many other factors, they are classified into two types- Natural and Synthetic polymers. The polymers which are generated naturally are called natural polymers, whereas polymers made by humans in some synthetic processes are called Synthetic polymers. There are different kinds of useful synthetic polymers. Thermosetting polymers are one kind of them.

Define Thermosetting Polymer

A thermosetting polymer can be called by another name ‘Thermoset’. By heating the thermosetting polymer, it undergoes irreversible changes. It has a cross-linking structure, forming a three-dimensional network. Initially, these polymers remain in a liquid state and they are soft. But after heating, they become harder. The rate of cross-linking in them increases with an increase in temperature, pressure, and amount of catalysts. Bakelite, Duroplast, and Melamine resin are examples of thermosetting polymers. 

Features of thermosetting polymers

This type of polymer has unique properties unlike the other types of polymers. 

1. Monomers are condensed easily and form polymers. Thermosetting polymers are types of condensation polymers.
2. Due to the high cross-linking process, the molecular weights of these are very high.
3. Thermosetting polymers possess exceptionally high melting points and very strong tensile strength.
4. It is not reprocessed to its original state because of the intense cross-linking. It is created permanently. In other words, the reaction mechanism is irreversible.

Synthetic pathway of Thermosetting Polymer

The initial stage of thermosets is a resoluble, molten, and insoluble state. Next, it transforms into a thermoplastic-like substance that is slightly soluble and has certain reversible properties. Following this phase, polymers undergo cross-linking and hardening. Finally, a 3D network containing polymers is formed. There is also another method of preparation containing three steps.

1. Moulding by compression: Here a heated mould cavity is used and then it is compressed to produce the plastic. With an increase in the application of heat on mould, the chemical interaction also increases.
2. Transfer moulding: The utilization of a transfer pot is common in this kind of manufacturing, and heating the mould within it, will enhance the materials’ flow.
3. Injecting the mould: Screws are employed in the injection moulding process to inject the high volume of polymer into the appropriate moulds. Additionally, it is discovered that the liquification of these polymers decreases the polymers’ viscosity.

Advantages of Thermosetting Polymers 

1. For thermosets, both chemical and heat resistance are excellent. It’s employed for packed items and has a strong deformation resistance.
2. Thermosets are beneficial for wet paste formulations since they contain minimal solvent.
3. The linked chains cannot freely travel because the use of heat turns them hard.
4. Epoxy and phenolic resins have a wide range of uses, particularly in the production of circuit boards and containers.

Disadvantages

1. It cannot be converted to its original state after it has formed.
2. With thermosets, fine surface quality is not achievable.
3. This polymer should be managed with utmost care.

Summary

Bulk molecules, known as polymers, have numerous industrial uses. There are two categories of polymers, both natural and artificial. Artificial synthetic polymers are generated by executing specific chemical changes. Because they’re irreversible polymers, even after heating, they cannot be reverted to their initial position. Therefore, it is an extremely rigid and hard polymer. During the curation process of thermosets, chemical interaction occurs in them. So remoulding is not possible. But for thermoplastic polymers, no chemical interaction occurs during curation. Due to the possibility of remoulding in thermoplastic polymers, thermosets are a better option than thermoplastic polymers.

 

Frequently Asked Questions

1. What are the reasons that thermosets don’t melt?

Ans: During the curation process, cross-linking occurs in the polymers to produce an unbreakable and permanent bonding. It is clear that even with the application of strong heat, thermosets can’t be melted.

2. What are the reasons behind the ignition of thermosets?

Ans: Thermosets possess significant melting points, but as soon as they reach a particular temperature and harden, their parts and physical features become fixed. They cannot be transformed back into their original shapes or sold for scrap again. Rather the substance will just burn or char.

3. Do thermosets participate in the crystallization process?

Ans: It is found that thermosets are amorphous in nature. Due to the high cross-linking process in their structures, they don’t crystallize.

Introduction

Circuit boards, plastic light fixtures, switches, and sockets can all be made of the synthetic material known as Bakelite. The characteristics include non-absorbency and non-conductivity, as well as high-temperature resistance. Because it is utilized in electronic devices, it is referred to as “Bakelite.” A heated mixture of granular phenolic resin, sawdust, and asbestos is used to make Bakelite, which is then poured into a mould. The phenolic resin was the first artificial resin. Plastic materials come in a wide variety. 

Types of plastics

They can be divided into two classes: Thermoplastics and Thermosetting.

Thermoplastics: These are the plastic materials used to make the handles of toothbrushes and bags. Thermoplastics are heated to convert into their different forms.

Thermosetting: After heating, the hardness of this plastic increases. Bakelite is one type of thermosetting plastic.

Bakelite preparation

Bakelite is prepared by following such steps.

1. 25 ml glacial acetic acid is taken in a beaker. 12.5 ml 40% formaldehyde solution is mixed with it and heated.
2. After some time, 10-gram phenol is added to it and at the end 12-15 ml of HCl solution is mixed.
3. It is put in a water bath and heated gently until a solid mass appears.
4. Then it is passed through the funnel, fitted with filter paper, and Bakelite remains as a solid compound.

Structure of Bakelite:

In the Bakelite structure, there is a cross-linking between phenol and formaldehyde. Bakelite can be written chemically as\(\;{({C_6}{H_6}O – C{H_2}OH)_n}\).

Properties of Bakelite

1. Bakelite can be easily generated, and the mouldings of Bakelite are corrosion and thermal-resistant.
2. It would be resistive to current flow because of its low conductivity to electricity.
3. Due to its low electrical properties and high heat resistance, Bakelite has also been used primarily in the production of mechanical and electrical components for electrical devices.
4. Bakelite contains phenolic components in the structure. For this, it is widely used in bindings.
5. Bakelite is moulded at a very rapid rate. 
6. Bakelite enables the production of extremely smooth mould.
7. Bakelite can endure harmful solvents.
8. When heated, it melts and solidifies. Then It becomes hard and can be moulded into desired shapes.
9. The cost of moulding decreases when an inert filler is used.

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Uses of Bakelite

1. To offer adequate security, it is used in parts that do not use radios or other electronic parts, such as plugs, buttons, hoods, wire cables, brakes, and so on and due to its shaping capacity, it is frequently used in everyday culture.
2. Due to its strong tensile strength and thermosetting nature, Bakelite may maintain its shape even after extensive production.
3. It has the ability to mould itself in various shapes, making this substance too much useful in modern society.
4. It is extensively used in making the parts of washing machines, cooking utensils, watches, toys, and many more.

Importance of Bakelite

1. Due to its many important uses as the first synthetic polymer, Bakelite has been appropriately termed “a thousand-use material.” Bakelite is used in the production of many products, including handles of plastic, telephones, ATMs, and so on.
2. Due to its strong resistance to both heat and electricity, it is used to produce numerous electronic components, sensors, and vehicle parts.
3. Besides these, the features of Bakelite are improved in various ways for better uses.

     For these reasons, Bakelite is so important in our daily life.

Summary

Being one of the most widely utilized thermoplastic materials in the nation, it is used to produce many other polymers. It’s vital to remember that because of the distinct characteristics of such a polymer, changing the temperature has little impact on the physical and chemical characteristics of that kind of substance. Having phenolic components in its structure, it is widely used in bindings. But it is very dangerous for human health.

Frequently Asked Questions

1. What occurs when Bakelite is heated?

Ans: As a result of heating a Bakelite, a watery condensation compound (Known as Bakelite A) is produced. Bakelite A becomes dissolved in acetone, alcohol, or extra phenol. Additional heating makes the product somewhat soluble, though the heat can still soften it. The consequence of prolonged heating is the formation of “insoluble, hard gum.”

2. Is Bakelite able to resist fire?

Ans: The handles of many kitchen appliances (fry pans, pressure cookers) are made of sturdy and long-lasting plastic known as Bakelite. It is also a bad conductor of electricity and heat, just like Melamine.

3. Is Bakelite resistant to chemicals?

Bakelite is a tough and chemically inert plastic that was created by combining phenol and formaldehyde. These two substances were obtained from coal tar and wood alcohol (methanol) respectively. Bakelite is inert to chemicals.