Plastics: Its Main Types and Properties

We can’t help but notice plastics when we glance around. They improve people’s lives by making them easier, safer, cleaner, and even more pleasurable. They are a general word for a variety of synthetic or semi-synthetic materials that are utilised in a variety of applications. Plastics may be found in our homes, clothing, automobiles, toys, screens, and medical equipment, among other places. 

What exactly is plastic? 

The word “plastic” comes from the Greek word “plastickos,” which means “mouldable.” This refers to the material’s malleability, or plasticity, which allows it to be cast or pressed into a variety of forms, including films, plates, fibres, bottles, boxes, and many more. Plastic, like synthetic fibres, is a polymer that can be moulded into desired shapes and sizes when flexible and hardened to create lasting objects. Physical and chemical characteristics of several kinds of plastics have been identified. Plastic is used to make a variety of items such as chairs, tables, buckets, toys, and balls. 

Plastics are a broad category of synthetic or semi-synthetic organic molecules that are pliable and may be moulded into solid things, as previously stated. Plastics, like wood, paper, and wool, are organic materials made from natural raw elements such as cellulose, coal, natural gas, salt, and crude oil. 

Plastics’ Characteristics 

Let us now look at some of the main properties of plastics :

  • They are chemically stable and low in weight. 
  • It may be easily moulded into a variety of forms and sizes. 
  • Low heat conductivity and good insulation. 
  • They have good impact resistance and do not rust.  
  • Transparency and wear resistance are both excellent. 
  • Dimensional stability is poor, and it is readily distorted. 
  • Processing costs are low. 

Types of Plastics

Plastics are divided into two categories: 

  1. Thermoplastics 
  2. Thermosetting Plastics 
  1. Thermoplastics: “thermoplastic” refers to polymers that do not alter chemically when exposed to high temperatures. When exposed to heat, these polymers do not alter their chemical structures or chemical compositions, and they can be remoulded in a soft state several times. Polystyrene, Teflon, Acrylic, Nylon, and other materials are examples. 
  2. Thermosetting Plastics: Thermosetting polymers, sometimes called thermosets, are plastics that can only be formed once and do not change shape when heated. These polymers can only be formed once and will not soften with further heat. When exposed to a considerable quantity of heat, these polymers degrade and get damaged. Vulcanized rubber, Polyurethane, Bakelite,  resin, Vinyl, ester resin, and other materials are examples. 


It is one of the world’s most widely used thermoplastics. Polyethylene (polyethene) is most commonly used in packaging. It’s commonly used to manufacture plastic bags, bottles, films, and containers, among other things. 

Properties of Polyethylene 

  • When subjected to a constant load, they display significant creep. 
  • Polyethylene’s mechanical strength is lower than that of other polymers. 
  • They are excellent electrical current insulators. 
  • The polymer’s stiffness and hardness are both quite low. 
  • When subjected to constant stress, they display significant creep. 

Polyethylene’s Structure 

The reaction of several ethylene molecules in the presence of a catalyst breaks the double bond and connects the carbon atoms into a chain, resulting in polyethylene. 

Polyethylene Types 

The plastic density and degree of branching in the structure of polyethylene may be used to classify it into distinct varieties. The mechanical characteristics and melting point of polyethylene vary accordin to the kind. 

  • Polyethylene with a high density (HDPE) 
  • Cross-linked polyethylene with a high density (HDXLPE) 
  • Polyethylene with a medium density (MDPE) 
  • The polyethylene that has been cross-linked (XLPE) 
  • Polyethylene with a low density (LDPE) 

Polyethylene’s Applications 

  • It’s utilised in product packaging. 
  • Because it is an excellent insulator of electric current, it is used for cable jacketing. 
  • Pipes, fittings, rubbish bags, food packaging, and other items are made of LDPE. 
  • Ropes, fishing and agricultural nets, and industrial textiles all employ HDPE 


Plastic is described as a material that comprises an organic compound with a high molecular weight as an important element. Polymers with long carbon chains are another definition. 

Plastic recycling is critical because if it is not done at the appropriate time, it can become combined with other chemicals or materials, making it more difficult to recycle and polluting the environment. They are non-biodegradable, and microbial activity does not readily degrade them. 

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