Problem 105 - A Complete Resource Book in Chemistry for JEE Main

Question

Identify the incorrect statement: (a) Kelvar is a nylon - polymer obtained by condensation of terephthalic acid and 1,4 - diamino benzene (b) Lexan is a nylon - polymer prepared by condensation of acrylic acid and vinyl cyanide. (c) Nomex is used in fire resistant protective clothing. (d) Vinyon is a co- polymer of vinyl chloride and vinyl acetate.

Step-by-Step Solution

Answer

Statement (b) is incorrect.

Step 1: Understand Each Statement

First, let's examine each statement individually to understand what polymer or co-polymer is involved and recall the correct definitions or components for each. This will help identify any discrepancies.

Step 2: Analyze Statement (a)

Statement (a) says that Kevlar is obtained by the condensation of terephthalic acid and 1,4-diamino benzene. This is correct; Kevlar is a type of para-aramid that results from this condensation reaction.

Step 3: Analyze Statement (b)

This statement indicates that Lexan is a nylon-polymer prepared by condensation of acrylic acid and vinyl cyanide. Lexan is actually a polycarbonate, not a nylon, usually made from bisphenol A and phosgene. Therefore, this statement is incorrect.

Step 4: Analyze Statement (c)

Statement (c) claims that Nomex is used in fire-resistant protective clothing, which is accurate. Nomex is a metaramid polymer known for its excellent heat and flame resistance.

Step 5: Analyze Statement (d)

Here, it states that Vinyon is a co-polymer of vinyl chloride and vinyl acetate. This is correct, as Vinyon is produced from these two compounds.

Key Concepts

Kevlar

Kevlar is an amazing material well known for its strength and durability. It's a synthetic fiber that belongs to the aramid family. This unique polymer is made through a condensation reaction involving terephthalic acid and 1,4-diamino benzene.
When these two components react, they form strong bonds, creating a rigid and robust structure. Kevlar is especially notable for being five times stronger than steel by weight! This strength makes Kevlar ideal for various applications, most famously in bulletproof vests and personal armor. It's also useful in other areas:

• Reinforcing materials in racing tires
• Rope and cable construction for its superior tensile strength
• Asbestos substitutes in automobile brake pads due to its heat resistance

Kevlar's fantastic strength, thermal stability, and lightweight nature make it a valuable material in both industrial and personal safety applications.

Lexan

Lexan is not just any polymer; it's a polycarbonate known for its transparency and impact resistance. Despite common misconceptions, it is not related to nylon. Instead, Lexan is created from the reaction between bisphenol A and phosgene, resulting in a highly durable material. Polycarbonates like Lexan are favored in various industries due to their useful properties:

• High impact resistance, making it a staple in aircraft canopies and bulletproof glass
• Optical clarity, perfect for lenses in glasses and commercial face masks
• Electrical insulation, suitable for electronics and electrical enclosures

These features make Lexan a versatile choice in manufacturing, offering both safety and functionality in its applications.

Nomex

Nomex is celebrated for its excellent flame-resistant properties. It's part of the meta-aramid family of materials, known for their ability to withstand extreme temperatures. Nomex is indeed used in firefighter suits, racing car driver uniforms, and more for its ability to self-extinguish once the flame source is removed. The inherent qualities of Nomex that contribute to its use in protective clothing include:

• Non-melting characteristic that provides added safety during exposure to heat
• High temperature resilience without deterioration
• Maintaining structural integrity after repeated washes and exposure to fire

These properties ensure that textiles made from Nomex protect individuals working in high-risk environments from severe burns and injuries.

Vinyon

Vinyon is an intriguing co-polymer made from vinyl chloride and vinyl acetate. Unlike the other polymers mentioned, Vinyon is notable for its properties such as softness, pliability, and resistance to damp environments. This polymer finds its niche in the production of products requiring particular attributes like:

• Adhesive qualities, useful for industrial applications
• Fishing nets, where durability and resistance to water damage are essential
• Fabrics treated for weather resistance, benefitting outdoor gear

Vinyon's adaptability allows it to be transformed into various forms, catering to specific industry needs, particularly where water resistance and flexibility are necessary.