What Are Synthetic Fibres?

The materials used to make the clothes we wear are called fabrics. Fabrics are woven from thinner strands called fibres. Fibres can originate from either natural sources (like plants or animals) or artificial/man-made sources.

Natural fibres, such as cotton, wool, and silk, are obtained directly from plants or animals. In contrast, synthetic fibres are created by human beings through chemical processes. Because they are made artificially, they are also known as man-made fibres or artificial fibres.

Just like a necklace is formed by joining many small beads together, or a long chain is made by linking many paper clips, a synthetic fibre is structured as a long chain made up of many small, repeating units linked together. Each of these small units is typically a chemical substance. When many such small units combine, they form a large single unit called a polymer.

The term 'polymer' originates from Greek words: 'poly' meaning many, and 'mer' meaning part or unit. Thus, a polymer is essentially a structure composed of many repeating units.

Polymers are not exclusively man-made; they also exist naturally. For instance, cotton is a natural polymer called cellulose, which is formed from a large number of repeating glucose units.

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Types Of Synthetic Fibres

Synthetic fibres are produced using different chemical processes, resulting in fibres with varying properties and uses. Some of the common types include Rayon, Nylon, Polyester, and Acrylic.

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Rayon

Silk, originally obtained from silkworms and discovered in China, was historically very expensive due to its beautiful texture. This led to attempts to create silk artificially. By the late nineteenth century, scientists succeeded in producing a fibre with properties similar to silk. This fibre, known as rayon or artificial silk, is obtained through the chemical treatment of wood pulp, which is a natural source. Although derived from a natural material, the chemical processing makes it a man-made fibre.

Rayon is cheaper than natural silk and can be woven just like silk fibres. It can also be easily dyed in a wide range of colours. Rayon is often blended with other fibres for different applications; for example, it's mixed with cotton to make bed sheets and with wool to make carpets.

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Nylon

Nylon is another significant man-made fibre, known for being the first *fully* synthetic fibre developed in 1931. It was created from chemical substances derived from coal, water, and air, without using any natural plant or animal raw materials.

Nylon fibre is highly valued for its properties: it is very strong, elastic, and lightweight. It also has a lustrous appearance and is easy to wash, which contributed to its popularity for clothing and various other items. Its remarkable strength means a nylon thread is actually stronger than a steel wire of comparable thickness.

Due to its strength and durability, nylon is used to make a wide variety of articles, including socks, ropes, tents, toothbrushes, car seat belts, sleeping bags, and curtains. It is also strong enough for more demanding applications like making parachutes and ropes used for rock climbing.

The strength of different fibres can be demonstrated by hanging weights from threads of the same length and thickness until they break. By comparing the total weight each type of thread can hold before breaking, their relative strengths can be determined.

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Polyester And Acrylic

Polyester is another widely used synthetic fibre. Fabrics made from polyester are known for being resistant to wrinkling; they remain crisp and are easy to wash, making them very suitable for dress materials. Terylene is a well-known form of polyester that can be drawn into extremely fine fibres used for weaving yarn.

A particularly common form of polyester is PET (polyethylene terephthalate). PET is extensively used for manufacturing bottles, utensils, films, wires, and many other products.

Polyester is a polymer made up of repeating units of a chemical group called an ester. Esters are chemical compounds often responsible for the pleasant smell of fruits.

Synthetic fabrics are often created by blending different types of fibres. Names like polycot, polywool, and terrycot indicate these blends. Polycot is a mix of polyester and cotton, while polywool is a mixture of polyester and wool.

Acrylic is another synthetic fibre that serves as a substitute for natural wool. Clothes like sweaters, shawls, and blankets used in winter are often made from acrylic because natural wool is quite expensive. Acrylic is comparatively cheaper and available in many colours. The durability and affordability of synthetic fibres like acrylic make them very popular compared to natural fibres.

A significant disadvantage of synthetic fibres, including polyester and acrylic, is that they melt on heating. If clothing made from synthetic fibre catches fire, the melting fabric can stick to the body of the person wearing it, causing severe burns. This is why it is advised not to wear synthetic clothes while working in environments with open flames or high heat, such as kitchens or laboratories.

All synthetic fibres are manufactured through various processes using raw materials derived from petroleum, which are known as petrochemicals.

Characteristics Of Synthetic Fibres

Synthetic fibres possess a set of desirable characteristics that contribute to their widespread popularity as clothing materials and for other applications. These properties include:

• They dry quickly after washing.
• They are durable, meaning they last a long time and resist wear and tear.
• They are generally less expensive compared to natural fibres.
• They are readily available and easy to produce on a large scale.
• They are easy to maintain (e.g., wrinkle-resistant, easy to wash).

Comparing pieces of fabric made from natural and synthetic fibres of similar size can illustrate some of these properties. When soaked in water, synthetic fabrics typically absorb less water than natural fabrics. Consequently, they also take less time to dry. These characteristics make synthetic fibres very convenient for many uses, especially in diverse weather conditions.

Plastics

Like synthetic fibres, plastic is also a polymer, made up of small repeating units. However, the arrangement of these small units is not always the same in all plastics. Some plastics have a linear arrangement of units (chains linked end-to-end), while others have a cross-linked arrangement, forming a more complex network structure.

Plastic materials can be molded into virtually any shape and size, which explains the enormous variety of plastic articles we see and use daily. This ability to be easily shaped is known as mouldability. Plastics can also be recycled, reused, coloured, melted, rolled into sheets, or drawn into wires, contributing to their diverse applications.

Polythene (Poly + ethene) is a common example of a plastic. It is widely used to make the familiar polythene bags.

Not all plastic articles behave the same way when bent or heated. Some plastics deform easily upon heating and can be bent or reshaped easily. These are called thermoplastics. Examples include polythene and PVC (Polyvinyl Chloride). Thermoplastics are used to manufacture items like toys, combs, and various types of containers.

In contrast, some plastics, once molded into a shape, harden and cannot be softened or reshaped by heating. These are known as thermosetting plastics. Examples include Bakelite and Melamine. Bakelite is a poor conductor of heat and electricity and is used for making electrical switches and handles of cooking utensils. Melamine is a versatile material that can withstand fire better than other plastics and tolerate heat. It is used for making items like floor tiles, kitchenware, and fabrics that are resistant to fire.

Plastics As Materials Of Choice

Plastics have become the preferred material for numerous applications today, including storing food items, water, milk, pickles, and dry goods. This preference stems from a combination of their advantageous properties.

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Plastic Is Non-reactive

Unlike many metals, such as iron which can rust when exposed to moisture and air, plastics do not react with water or air. They are not easily corroded. This makes them ideal for storing various materials, including different chemicals, without fear of the container degrading or reacting with the contents.

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Plastic Is Light, Strong And Durable

Plastics are significantly lighter than metals yet possess good strength and durability. Their ability to be molded into diverse shapes and sizes further adds to their utility. These properties make them suitable for a vast array of purposes, from everyday household items like buckets, mugs, and containers to components in cars, aircraft, and spacecraft. Plastics are also generally more affordable than metals, making them widely used in both industry and for consumer goods.

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Plastics Are Poor Conductors

Plastics are poor conductors of both heat and electricity. This property is utilized in many applications. For example, plastic is used as insulating covering for electrical wires and for making handles of tools like screwdrivers and frying pans to prevent electric shock or heat transfer.

Interesting uses of plastics in specialised areas include:

• Healthcare: Used extensively for packaging medicines (tablets), threads for stitching wounds, syringes, medical gloves, and various medical instruments.
• Microwave Ovens: Special plastic cookware is used in microwave ovens; the heat generated cooks the food but does not affect the plastic container.
• Teflon: A specific type of plastic used as a non-stick coating on cookware because oil and water do not stick to its surface.
• Fire-proof Plastics: Although most synthetic fibres are easily flammable, some plastics like melamine are used to make materials flame resistant. For instance, firemen's uniforms often have a coating of melamine plastic for protection.

Plastics And The Environment

The widespread use of plastic poses a significant environmental challenge. Plastic packaging and bags contribute to a large amount of waste accumulated in our homes and ultimately in garbage disposal sites. The main issue is the disposal of plastic waste.

Materials are classified based on how they decompose in nature:

• Biodegradable: Materials that can be decomposed by natural processes, such as the action of bacteria (e.g., plant and animal waste).
• Non-biodegradable: Materials that are not easily decomposed by natural processes (e.g., most plastics, metals).

The following table illustrates the approximate time taken for various materials to degenerate:

Type of Waste	Approximate Time Taken to Degenerate	Nature of Material
Peels of vegetable and fruits, leftover foodstuff, etc.	1 to 2 weeks	Biodegradable
Paper	10 to 30 days	Biodegradable
Cotton cloth	2 to 5 months	Biodegradable
Wood	10 to15 years	Biodegradable
Woollen clothes	About a year	Biodegradable
Tin, aluminium, and other metal cans	100 to 500 years	Non-biodegradable
Plastic bags	Several years	Non-biodegradable

Since plastic takes many years to decompose, it remains in the environment for extended periods, causing pollution. Burning plastic is also not an ideal solution because it burns slowly and releases harmful, poisonous fumes into the atmosphere, contributing to air pollution.

Addressing the plastic waste problem requires conscious effort. It is advisable to minimize the use of plastic whenever possible. Using alternative bags made of cotton or jute for shopping is a good step. Segregating biodegradable and non-biodegradable waste at the source (homes) helps in proper disposal.

Recycling plastic waste is a better approach, especially for thermoplastics which can be remolded. However, during recycling, colouring agents are often added, which can limit the use of recycled plastic, particularly for food storage.

As responsible citizens, we should adopt the 5 R principle to reduce environmental harm caused by plastics: Reduce, Reuse, Recycle, Recover, and Refuse. Developing habits that are environmentally friendly is crucial.

Carelessly discarded plastic bags pose a threat to animals. Animals eating garbage can swallow plastic materials, which can choke their respiratory system or block their digestive tracts, leading to death. Plastic bags also clog drains, causing water logging and sanitation problems. It is important to be mindful and avoid littering public places with plastic waste.

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