Types of Fibres
- Natural Fibre: Fibres which are obtained from plants and animals are called natural fibres, e.g. cotton, wool, silk, jute, etc.
- Synthetic Fibre: Fibres which are man-made are called synthetic fibres, e.g. nylon, acrylic, etc. A synthetic fibre is made of multiple units of a chemical substance. The units in a fibre are joined together like a chain.
- Petrochemicals: Almost all synthetic fibres are made using raw materials from petroleum. Such raw materials which come from petroleum are called petrochemicals.
- Polymer: A chain of a particular chemical substance is called a polymer. The individual unit in a polymer is called the monomer. Thus, a polymer is made up of many monomers. All synthetic fibres are polymers. Even cotton is a polymer.
Types of Synthetic Fibre
Rayon: Rayon was discovered towards the end of the nineteenth century. It was made by chemical treatment of wood pulp and was the first synthetic fibre.
- Rayon is similar to silk but is cheaper than silk. Hence, rayon is also called ‘poor man’s silk’.
- Rayon can be dyed in various colours.
- Rayon is usually mixed with cotton to make bed sheet and dress materials.
Nylon: Nylon was made in 1931. The term ‘nylon’ has been derived from letters of ‘New York’ and ‘London’. No ingredient from plant or animal source was used in making nylon, as it is made from coal, water and air. Hence, nylon is called the first truly synthetic fibre.
- Nylon is strong, light and elastic.
- It is lustrous and easy to wash.
- Nylon is used in many articles; like socks, bags, toothbrush, rope, sneakers, parachute, etc.
- For the same thickness, a nylon thread is stronger than a steel wire.
Polyester: Polyester is made of repeating units of a chemical called ester.
- Terylene is popular polyester which is used in dress materials.
- PET (Poly Ethylene Terephthalate) is another example of polyester. It is used for making bottles, utensils, films, wires and many other items.
- Polyester fabrics do not wrinkle easily and are easy to wash.
Acrylic: Acrylic resembled wool and hence is also called synthetic wool. It is cheaper and more durable than wool and is easier to wash and maintain.
Characteristics of Synthetic Fibres
- They are less expensive.
- They are readily available.
- They can be easily washed.
- They are easy to maintain.
Plastic too is a polymer. But the arrangement of units is different in different types of plastic. In some plastics, the individual units are linked in a linear fashion. In some other plastics, the individual units are cross-linked.
Types of Plastic
- Thermoplastic Plastic: Some plastics easily get deformed on heating, and can be easily bent and reshaped by heating. They are called thermoplastic. Polythene and PVC are examples of thermoplastic. Thermoplastic is used for making combs, toys, buckets, mugs, etc.
- Thermosetting Plastic: Some plastics do not get deformed on heating, and cannot be re-moulded into a new shape. Such plastics are called thermosetting plastic. Bakelite and melamine are examples of thermosetting plastic. Bakelite is used for making electrical switches and switchboards because it is a poor conductor of heat and electricity. Melamine is resistant to fire and is hence used for making utensils.
Reasons for popularity of plastic
- Plastic is non-reactive: Unlike iron, plastic does not react with air to form rust. Due to this, plastic has replaced iron from many articles. Plastic does not react with many chemicals, and so, plastic containers are used for keeping many materials and chemicals.
- Plastic is light, strong and durable: Plastic is lightweight, strong and durable. Plastic chairs have replaced wooden chairs in most of the households. Wooden crates have been replaced by plastic crates; for keeping milk and cold drinks. Most of the warehouses now use plastic pellets for keeping goods.
- Plastic is poor conductor of heat and electricity: Because of poor conductivity to heat and electricity; plastic is used for making switches and many components of electrical appliances. Handles of utensils are made of plastic because such handles do not heat up.
Plastic and the Environment
Biodegradable: A material which can be decomposed by microbes is called a biodegradable material, e.g. jute, cotton, paper, leftover food, etc.
Non-biodegradable:A material which cannot be decomposed by microbes is called a non-biodegradable material, e.g. plastic, iron, copper, etc.
The non-biodegradable nature of plastic poses a big problem. Plastic has become very popular due to many of its inherent benefits. But the popularity of plastic is proving to be a curse for the environment. Plastic waste is getting accumulated all around us, in the street, on the sidewalk, in drains, on garbage dumping sites, etc. This is creating a burden of plastic waste on the earth.
Nuisance of plastic bags
- Plastic bag keeps on accumulating in the environment.
- It chokes drains.
- A stray animal can die if it accidentally swallows plastic bag.
Fibrous Materials and Their Uses
- Fibrous materials have been used in various fields over the years. Fibre has often been used to manufacture other materials. The strongest engineering materials tend to put fibre to good use. Synthetic fibres, however, are cheaply produced compared to the natural ones. But when it comes to clothing natural fibres are more comfortable.
- The use of fibrous materials in civil engineering, both as structural reinforcement and in non-structural applications such as geo-textiles, is an important and fascinating development. Fibrous and composite materials for civil engineering applications analyze the types and properties of fibrous textile and structures and their applications in reinforcement and civil engineering. Fibrous materials are known to capture the air within the fibres and this prevents heat transmission by convection and limits gaseous heat conduction by minimizing collisions between gas molecules. They are hence suitable or pretty many perfect materials for effective thermal insulation.
- Fibres are often used in the form of a yarn because a multi-filament yarn is more flexible and pliable than a solid monofilament of the same diameter. Knitting is another way of producing fibre and it involves interlacing of yarn and it has high extensibility in all directions. Braiding involves interlocking of the yarn in a bias and it has high torsion stability. The fibres can easily nest together and get stuck between pleats of conventional cartridge filter making them very difficult to remove during pulse cleaning and building up pressure drop on the filter. Even though there are difficulties related to it, the advantages are enough to overcome them.