Problem 96 - A Complete Resource Book in Chemistry for JEE Main

Question

Which is/are correct about spandex? (I) It is a poly urethane (II) It is a flexible polymer (III) It is a polymer of toluene 2,6 di isocyanate and glycol (IV) It is a polymer of ammonum carbamate (a) I, II, III (b) I, II, IV (c) II, II, IV (d) I, II, III, IV

Step-by-Step Solution

Answer

Correct statements are I, II, and III, so option (a) is correct.

Step 1: Understanding Spandex Composition

Spandex, also known as elastane, is a synthetic fiber known for its exceptional elasticity. It is primarily composed of polyurethane, which is a polymer made by linking diisocyanates with polyols.

Step 2: Analyzing Statement I

Statement I: 'It is a polyurethane.' This statement is true as spandex is indeed made from polyurethane.

Step 3: Analyzing Statement II

Statement II: 'It is a flexible polymer.' This is also true because spandex is renowned for its flexibility and ability to stretch.

Step 4: Analyzing Statement III

Statement III: 'It is a polymer of toluene 2,6 di isocyanate and glycol.' This statement may refer to a specific type of polyurethane synthesis, which can be accurate depending on the specific formulation of the spandex. Hence, this statement can also be considered true.

Step 5: Analyzing Statement IV

Statement IV: 'It is a polymer of ammonum carbamate.' This statement is incorrect because ammonium carbamate is not involved in the synthesis of spandex.

Step 6: Determining the Correct Options

The correct statements are I, II, and III. Therefore, the correct answer is (a) I, II, III.

Key Concepts

Polyurethane

Polyurethane is a versatile material, known for its use in a multitude of products, including spandex. At its core, polyurethane is a polymer, a large molecule composed of repeated subunits known as monomers. The formation of polyurethane involves a chemical reaction between polyols and diisocyanates. Through this process, a network of strong covalent bonds is created, endowing the material with a range of desirable properties.
- **What makes polyurethane special?** It provides excellent durability and elasticity, making it perfect for applications where flexibility is crucial, such as in the production of stretchable fabrics.
- **Versatile Uses:** Beyond textiles, polyurethane is found in foams, coatings, adhesives, and even medical devices. Understanding polyurethane is vital for appreciating how spandex achieves its unique stretchiness and resilience. The durability of polyurethane also contributes to the long-lasting nature of products made from spandex, ensuring they return to their original shape after being stretched.

Flexible Polymer

A flexible polymer, like the one found in spandex, has unique properties that allow it to stretch and return to its original form without losing strength. This incredible ability is what makes spandex such an essential material in industries where comfort and versatility are a necessity.
- **Key Features:**
- Elasticity: The ability to stretch and bounce back
- Toughness: Resists damage from repeated physical stress
These properties stem from the molecular structure of flexible polymers, which includes a nonlinear arrangement and presence of soft segments that allow for movement and stretching.
Flexible polymers are not restricted to textiles alone. They play a crucial role in many products like hoses, seals, and even footwear, highlighting their importance across different applications.

Synthetic Fiber

When discussing synthetic fibers, we refer to fibers that are man-made rather than sourced naturally. Spandex is one such synthetic fiber, and it is produced by processes involving chemical synthesis instead of raw natural compounds. This process allows for intense control over the characteristics of the fiber.
- **Benefits of Synthetic Fibers:**
- Customizable properties, such as stretchability and strength
- Enhanced durability compared to many natural fibers
- Resistance to elements like moisture and mildew
Synthetic fibers like spandex are not only popular in clothing but also find roles in various technical applications, such as in medical braces and support garments. The ability to design and alter the fiber properties gives manufacturers the freedom to create specialized products meeting particular needs.