Question

Which of the following is not made of polyamides? (a) nylon (b) natural silk (c) wool (d) artificial silk

Short answer

Artificial silk (d) is not made of polyamides.

Step-by-step solution

Understand the Problem

We need to determine which of the options is not made of polyamides. A polyamide is a type of polymer that contains recurring amide groups (–CO–NH–) in the main chain.

Examine Each Option

Identify which options are made from polyamides. - **Nylon:** A synthetic polymer and a well-known example of a polyamide. - **Natural Silk:** A natural protein fiber, which is also a type of polyamide. - **Wool:** A natural fiber made mostly of proteins, which can be considered a polyamide. - **Artificial Silk:** Also known as rayon, it is not a polyamide but is made from cellulose, a polymer derived from plant material.

Identify the Exception

From the examination in the previous step, artificial silk (rayon) is distinguished by being made from cellulose, and not having the amide groups characteristic of polyamides.

Key concepts

Nylon

Nylon is a highly popular synthetic polymer, widely used in various applications due to its exceptional properties. At its core, nylon is a type of polyamide, meaning it contains recurring amide groups, specifically having the structure \(-CONH-\) in its molecular chain. This gives nylon its strong and resilient nature.

Nylon was first synthesized in the 1930s as a substitute for silk and has since become a staple in the textile industry. It's renowned for its elasticity, durability, and resistance to wear and tear.

• **Composition**: Nylon's structure is derived from petroleum products like benzene and is formed through a process known as polycondensation.
• **Applications**: It's used in making everything from clothes like stockings and tights to everyday items such as ropes, fishing lines, and even carpets.
• **Properties**: Nylon fibers are characterized by their strength, smooth texture, and ability to dry quickly after becoming wet.

Nylon's versatility and strong chemical makeup make it ideal for industrial and domestic uses, proving its resilience across various conditions.

Natural Silk

Natural silk holds a reputation for luxury, boasting a rich history and exquisite texture. This natural fiber is produced by silkworms, most notably from the Bombyx mori species. The silkworm spins its cocoon from a continuous fiber made mainly of a protein called fibroin, functioning as a natural polyamide.

Silk’s unique sheen and softness make it highly desired for fine garments and decorative textiles. Due to its protein composition, silk has several noteworthy qualities:

• **Thermal Properties**: It has excellent thermal regulation, keeping you cool in the summer and warm in winter.
• **Moisture Absorption**: Silk can absorb a substantial amount of moisture without feeling clammy, making it agreeable to wear in various climates.

Besides its aesthetic appeal, silk remains a significant textile thanks to its strength and insulation ability. It's also important in medical sutures and as material in parachutes because of its flexibility and weight.

Natural silk, despite being a polyamide, differs from synthetic types like nylon, offering distinct properties intrinsic to its biological origins.

Wool

Wool is a natural fiber obtained primarily from sheep. It is well-known for its warmth and moisture-wicking properties, which make it ideal for cold-weather clothing and accessories.

Similar to silk, wool is composed of proteins, making it a natural polyamide. The proteins in wool have a complex structure that gives this fiber unique properties:

• **Insulating Ability**: Wool is excellent at trapping air, making it a superb insulating material.
• **Water Resistance**: Wool fibers can wick moisture away while still maintaining an element of water resistance, adding to its functionality in diverse weather conditions.
• **Elasticity**: Wool fibers can be bent over 20,000 times without breaking, showcasing remarkable durability.

Wool's resilience and natural blending properties contribute to its widespread use across various textile applications, from fashion garments to home textiles.

Even though being a polyamide, wool offers natural characteristics that synthetic fibers attempt to replicate. Its eco-friendly aspects and multifunctionality keep it highly favoured in numerous applications.

Artificial Silk

Artificial silk, commonly known as rayon, distinguishes itself from other fibers like nylon, natural silk, and wool, by its origins and composition. Unlike polyamides, rayon is derived from cellulose—a natural polymer obtained from wood pulp or cotton linters.

Rayon attempts to mimic the feel and texture of natural silk, hence its "artificial silk" moniker.

• **Production**: The cellulose undergoes a chemical process to be transformed into fibers that exhibit silk-like qualities.
• **Characteristics**: Rayon is lightweight, highly absorbent, and drapes well, making it suitable for clothing and textile products.
• **Varieties**: It exists in several forms, such as viscose and lyocell, each differing slightly in production methods and fiber properties.

It’s important to note that, although rayon offers a silk-like sheen and soft touch, its cellulose base makes it less wrinkle-resistant compared to true polyamides like nylon.

Rayon's versatility and affordability continue to make it a popular choice in the textile industry, despite not possessing the fundamental polyamide structure of the other fibers discussed.