Problem 102 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is a condensation polymer? (a) Polyacrylonitrile (b) Bakelite (c) Glyptal (d) Nylon -6,6

Step-by-Step Solution

Answer

Bakelite, Glyptal, and Nylon-6,6 are condensation polymers.

Step 1: Understanding Condensation Polymerization

Condensation polymerization occurs when monomers join together through the loss of small molecules such as water, alcohol, or HCl. This type of polymerization typically involves the reaction of monomers with two different functional groups.

Step 2: Evaluating Each Option

Let's evaluate each option to check if they are formed through condensation polymerization: (a) Polyacrylonitrile is produced by the addition polymerization of acrylonitrile. (b) Bakelite is formed by the reaction between phenol and formaldehyde, releasing water as a byproduct, hence it's a condensation polymer. (c) Glyptal is made from the polycondensation of phthalic anhydride and glycerol, releasing water as a byproduct. (d) Nylon-6,6 is produced through the condensation reaction of hexamethylene diamine and adipic acid, releasing water as a byproduct.

Step 3: Identifying Condensation Polymers

From the analysis, Bakelite, Glyptal, and Nylon-6,6 are condensation polymers since they all involve the loss of small molecules like water during their formation.

Key Concepts

Polyacrylonitrile

Polyacrylonitrile, often abbreviated as PAN, is a type of polymer that's known for its strength and resistance to various chemicals. It is not a condensation polymer. Instead, it is formed through addition polymerization, meaning the process doesn't involve the loss of small molecules such as water or alcohol.
Instead, monomers of acrylonitrile link together by opening their double bonds and forming a long chain without releasing any byproducts.

• Addition polymerization involves only one type of functional group.
• There is no elimination of molecules during the formation.
• This process creates strong and stable polymers.

Polyacrylonitrile has important applications in the production of synthetic fibers like nylon or even as a precursor for carbon fibers used in high-performance areas like aerospace applications.

Bakelite

Bakelite is a classic example of a condensation polymer. This polymer is formed from the reaction between phenol and formaldehyde. It's an iconic plastic due to being one of the first synthetic polymers ever made. During its formation, small molecules such as water are released.
This process involves the reaction of two different functional groups:

• Hydroxyl group from phenol.
• Aldehyde group from formaldehyde.

These groups react to form a three-dimensional network of bonds, which makes Bakelite highly heat-resistant and durable. Due to these properties, Bakelite is often used in products that need to withstand heat, like electrical insulators and kitchenware.

Glyptal

Glyptal is another well-known condensation polymer. This polymer is formed by the condensation of phthalic anhydride and glycerol, with water being a byproduct of the reaction.
The creation of Glyptal includes:

• Reaction between an acid anhydride group and a hydroxyl group.
• Formation of ester linkages in the polymer chain.

The process yields a polyester known for its excellent insulating properties and low cost. Glyptal finds widespread use in the production of paints, varnishes, and coatings. Its robustness makes it a frequent choice for use in electrical applications, where insulation is key.

Nylon-6,6

Nylon-6,6 is a prime example of a synthetic condensation polymer resulting from the polymerization of hexamethylene diamine and adipic acid. During its synthesis, water molecules are released as byproducts.
The formation process involves:

• Diamine and diacid reacting to form amide bonds.
• Repeating units forming a strong polymer chain.

Due to its high tensile strength and resistance to wear, Nylon-6,6 is extensively used in the textiles industry. It appears in a variety of applications such as clothing fibers, automotive parts, and even in engineering plastics. Its versatility and strength make it a staple in manufacturing diverse products.