Introduction:
In 1846, the renowned German chemist Christian Schonbein discovered plastic. Plastics have actually been mistakenly identified. In his kitchen, Christian was experimenting, and he accidentally spilled a mixture of nitric acid and sulphuric acid. He took a cloth to mop up the solution (a mixture of nitric and sulphuric acid) and placed it over the stove after moping. After some time, the fabric vanished and got name plastic. In this article, you will study what is plastic, different types of plastic, properties of plastic, and recycling of plastic.
What is Plastic?
Plastic is defined as a material that contains an organic substance of greater molecular weight as an important ingredient. It is also characterized as polymers with long chains of carbon. All plastics are said to be polymers.
The word plastic was derived in Greek from the word 'Plastikos' which means 'to mold.' Fossil fuels have hydrogen and carbon (hydrocarbon) containing compounds that act as building blocks for long polymer molecules. Such building blocks are referred to as monomers, which bind together to form long chains of carbon called polymers.
Types of Plastic and Their Uses
There are two different types of plastic
Thermoplastic:
plastics that are easy to bend when heated. Thermoplastics include linear polymers and a mixture of linear and cross-linked polymers. For instance, PVC, nylon, polythene, etc.
Thermosetting:
Plastics that, once molded, can not be softened again by heating. Heavily cross-linked polymers fall into the thermosetting plastics group. Bakelite, melamine, etc. Example: Bakelite is used to make electrical switches, while floor tiles use melamine.
Speaking about the variations between thermoplastic and thermosetting plastic, the key differentiating factor between the two is that thermoplastic products usually have low melting points, meaning they can be quickly remolded or recycled further.
The thermosetting plastic, on the other hand, is quite the contrary. They can withstand high temperatures and, even with the application of heat, can not be reformed or recycled once hardened. In any event, let's take a look at some of the major differences below between these two compounds.
Types of Plastic Materials
Examples of thermoplastics are listed below.
Polystyrene
Teflon
Acrylic
Nylon
Examples of thermosetting polymers include:
Vulcanized rubber
Bakelite
Polyurethane
Epoxy resin
Vinyl ester resin
Plastic Material Properties
Here are some plastic material properties-
They are light weighted.
They are highly resistant to chemicals.
They are high electrical strength.
They can easily be molded to desired shape and size.
They can be made transparent or colored.
Operations like drilling, sawing, and punching can be done on plastics.
They are cheap as compared to metals.
They are strong and ductile
They are poor conductors of electricity.
Plastic resists corrosion.
Recycling of Plastic
Plastic recycling is very significant. If they are not recycled at the right time, they are mixed with other chemicals or products, making them harder to recycle and a source of pollution.
They are non-biodegradable, and the microbial effect does not decompose them.
It is important to use biopolymers or biodegradable polymers to prevent this.
Did You Know?
In a landfill, plastic takes up to 1,000 years to decay. It takes 88 percent less energy to recycle plastic than to produce plastic from raw materials. Every year, enough plastic is thrown away to orbit the Earth four times. Each year, Americans throw 35 billion plastic bottles away.
FAQs on Plastics
1. What are plastics in chemistry?
Plastics are synthetic or semi-synthetic materials made from long-chain molecules called polymers. These polymers are primarily composed of carbon atoms, often derived from natural resources like crude oil, natural gas, or coal. The term 'plastic' comes from the Greek word 'plastikos', meaning 'to mould', which highlights their key property of being easily shaped into various forms.
2. What are the two main types of plastics and their key differences?
The two main types of plastics are thermoplastics and thermosetting plastics. Their primary difference lies in how they respond to heat.
- Thermoplastics: These plastics soften when heated and harden again when cooled. This process is reversible, allowing them to be repeatedly melted and remoulded. Examples include Polythene, PVC, and Nylon.
- Thermosetting Plastics: These plastics are moulded once and become permanently hard. Reheating does not soften them; instead, they will char or burn. This is due to their strong, cross-linked molecular structure. Examples include Bakelite and Melamine.
3. What are the general properties of plastics that make them so widely used?
Plastics have several unique properties that make them useful in many applications:
- Lightweight and Strong: They have a high strength-to-weight ratio compared to materials like metal.
- Corrosion Resistant: They do not rust or corrode when exposed to chemicals or moisture.
- Poor Conductors: They are excellent insulators for both heat and electricity, making them ideal for safety applications.
- Malleable: They can be easily moulded into complex shapes and sizes.
- Durable and Cost-Effective: They are generally long-lasting and cheaper to produce than many alternatives like metal or glass.
4. Why can thermoplastics be recycled but thermosetting plastics generally cannot?
This difference is due to their molecular structure. Thermoplastics consist of long, individual polymer chains held together by weak intermolecular forces. When heated, these forces are easily overcome, allowing the chains to slide past each other, making the material melt and flow. This process is reversible. In contrast, thermosetting plastics have strong, permanent chemical bonds (cross-links) that connect all the polymer chains into a rigid, 3D network. Heating cannot break these strong bonds without destroying the material itself, which is why they cannot be remelted and recycled.
5. What is the difference between a monomer and a polymer?
A monomer is a small, single molecule that acts as a basic building block. A polymer is a very large molecule, also known as a macromolecule, formed when many monomers link together in a repeating chain. This formation process is called polymerisation. For example, in polythene, the monomer is ethene (C₂H₄), and the polymer is the long chain of thousands of ethene units linked together.
6. How do the properties of plastics make them useful for electrical applications?
Plastics are used as electrical insulators because they are poor conductors of electricity. The electrons in plastic molecules are tightly bound within their chemical bonds and are not free to move and carry an electric current. This high electrical resistance prevents the flow of electricity, making plastics ideal for applications like coating electrical wires (e.g., PVC), making switches and plugs (e.g., Bakelite), and creating casings for electronic devices.
7. Are all polymers considered plastics?
No, not all polymers are plastics, although all plastics are polymers. The term 'plastic' specifically refers to polymers that can be moulded or shaped. There are many natural polymers that are not plastics, such as starch, cellulose, and natural rubber. While these are all large-chain molecules (polymers), they do not all share the mouldable characteristic of synthetic plastics.
8. Why are most plastics non-biodegradable?
Most plastics are non-biodegradable because the strong carbon-carbon bonds that form their polymer backbone are not recognised by the enzymes of microorganisms like bacteria and fungi. These organisms have evolved to break down natural materials, but the synthetic structures of plastics are foreign to them. As a result, plastics persist in the environment for hundreds or even thousands of years without decomposing naturally.
