Question 26 (Textile Engineering & Fibre Science)
Match the elements of Group I and Group II
|Group I||Group II|
|P. Polypropylene||1. Poor hydrolytic stability|
|Q. Cotton||2. Excellent thermal resistance|
|R. Polyester||3. Excellent elastic recovery|
|S. Wool||4. Poor resistance to acid|
|5. Higher wet strength|
|6. Excellent chemical resistance|
|(A)||P-6, Q-5, R-1, S-3|
|(B)||P-2, Q-5, R-6, S-3|
|(C)||P-4, Q-5, R-1, S-2|
|(D)||P-6, Q-1, R-2, S-3|
Frequently Asked Questions | FAQs
Why is polypropylene chemical resistant?
Polypropylene is a thermoplastic polymer that is known for its exceptional chemical resistance. This property is primarily due to its molecular structure, which is highly resistant to chemical degradation.
Polypropylene is composed of repeating units of propylene monomers, which are joined together through covalent bonds. The chemical structure of polypropylene is relatively simple, consisting of a linear chain of carbon atoms with hydrogen atoms attached to them. This makes the material highly stable and resistant to chemical reactions.
In addition to its stable molecular structure, polypropylene also has a low surface energy, which makes it difficult for other substances to adhere to its surface. This property reduces the chances of chemical reactions occurring on the surface of the material.
The chemical resistance of polypropylene makes it a popular material for use in a wide range of applications, including chemical storage tanks, laboratory equipment, and medical devices. It is also used in packaging materials, automotive components, and textiles, among other things.
Why cotton has high wet strength?
Cotton is a natural fiber that is known for its high wet strength, which means it retains its strength when wet. This property is due to the unique structure of cotton fibers and the chemical properties of cellulose, the main component of cotton.
Cotton fibers are made up of bundles of individual cellulose molecules, which are held together by hydrogen bonds. These hydrogen bonds give cotton fibers their strength and make them resistant to breaking when wet.
In addition to its hydrogen bonding structure, cotton fibers also have a unique cross-sectional shape that allows them to interlock with each other. This creates a dense, three-dimensional structure that further enhances the wet strength of cotton.
Furthermore, cotton fibers have a high degree of crystallinity, which means they are well-organized and tightly packed. This molecular structure also contributes to the strength and durability of cotton, both when dry and wet.
Overall, the combination of hydrogen bonding, interlocking fibers, and crystalline structure makes cotton an excellent material for applications that require high wet strength, such as towels, washcloths, and other textiles that will be exposed to moisture.
Is polyester susceptible to hydrolysis?
Polyester is a synthetic polymer that is commonly used in a variety of applications due to its excellent mechanical and chemical properties. However, it is susceptible to hydrolysis under certain conditions.
Hydrolysis is a chemical reaction in which a polymer is broken down into its constituent monomers by the addition of water. This can occur when polyester is exposed to water at high temperatures or under acidic or basic conditions. The hydrolysis reaction can cause polyester to lose its mechanical strength and other physical properties over time.
The susceptibility of polyester to hydrolysis depends on its chemical structure, molecular weight, and the specific environmental conditions to which it is exposed. For example, polyester fibers used in outdoor applications may be exposed to rain, moisture, and temperature fluctuations, which can accelerate hydrolysis and lead to degradation of the material.
To mitigate the effects of hydrolysis on polyester, manufacturers may add stabilizers or other chemical additives to the material to increase its resistance to water and other environmental factors. Additionally, proper storage and handling of polyester products can help prolong their lifespan and prevent hydrolysis from occurring.
Why does wool have good elasticity?
Wool is a natural fiber that is known for its excellent elasticity, which refers to its ability to stretch and then return to its original shape. The elasticity of wool is due to its unique physical and chemical properties, which are a result of its molecular structure.
Wool fibers are composed of protein molecules that are arranged in a helical structure. These helices can unwind and stretch when wool fibers are subjected to external forces, such as tension or pressure. When the external forces are removed, the helices will spring back to their original configuration, causing the wool fibers to return to their original shape.
In addition to its helical protein structure, wool also contains a network of interlocking scales that cover the surface of each fiber. These scales allow wool fibers to slide over each other without breaking, which further enhances their elasticity and ability to return to their original shape.
Finally, wool fibers are able to absorb moisture without losing their elasticity. This is due to the presence of amino acid residues in the protein structure of wool, which can bind with water molecules and maintain the integrity of the fiber.
Overall, the combination of a helical protein structure, interlocking scales, and moisture absorption capabilities make wool an excellent material for applications that require good elasticity, such as clothing, blankets, and carpets.