What material is plastic made of?
As an indispensable material in modern life, plastics are widely used in many fields such as packaging, electronic equipment, automobiles, and construction. What materials are plastics made of? This actually involves the complex science of polymers in the chemical industry. Plastics are made from a variety of synthetic or semi-synthetic polymers, and these polymer raw materials are processed through specific processes into the everyday items we know. In the following, we will analyse in detail the composition of plastics and the process of their preparation.
1. Basic components of plastics: polymers
What are plastics made of? The central answer is polymers. A polymer is a chain of high molecules made up of a large number of repeating monomers connected by a polymerisation reaction. Common polymers include polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC). Different types of plastics exhibit different physical and chemical properties depending on the type of monomer used, the method of polymerisation and the molecular structure.

Polyethylene (PE): polymerised from ethylene monomer, commonly used in the manufacture of plastic bags, food packaging films, etc.
Polypropylene (PP): polymerisation of propylene monomer, with good heat resistance, widely used in plastic bottle caps, household utensils.
Polystyrene (PS): polymerised from styrene monomer, transparent and easy to form, commonly used in the production of disposable tableware, packaging materials.

2. Additives used in the production of plastics
In addition to polymers, plastics contain a variety of additives that are used to enhance their properties or reduce production costs. These additives include antioxidants, plasticizers, stabilizers, colouring agents, fillers and so on. The type and amount of additives directly affect the physical properties and uses of the plastic.

Plasticisers: increase the flexibility of plastics and make them easier to process and mould. Commonly used in PVC production.
Antioxidants: prevent the plastic from aging due to oxidation during production and use, and improve its durability.
Fillers: such as calcium carbonate, talcum powder, used to increase the hardness and stability of plastic, while reducing production costs.

3. Plastic production process: polymerisation reaction and moulding technology
The production of plastics is mainly divided into two stages: polymerisation reaction and moulding. Monomers are converted into polymers through chemical reactions. Depending on the method of polymerisation, it can be divided into free radical polymerisation, anionic polymerisation, cationic polymerisation and copolymerisation. Next, the polymer is processed into products of the desired shape by injection moulding, extrusion, blow-moulding and other processes.

Injection moulding: Heated molten plastic is pressed into a mould and shaped, commonly used in the production of daily-use plastic products.
Extrusion: Plastic is heated and then formed by extrusion, suitable for making continuous products such as pipes and films.
Blow-moulding: Molten plastic is blow-moulded and used to make hollow products such as bottles.

4. Development trend of eco-friendly plastics
With the rise of environmental awareness, people have put forward more environmental requirements for the production and use of plastics. Degradable plastics, bio-based plastics and recycled plastics are becoming the new direction of development.

Degradable plastics: such as polylactic acid (PLA), can be gradually degraded to carbon dioxide and water in the natural environment.
Bio-based plastics: polymers made from plant raw materials, such as corn and sugar cane, obtained through biological transformation.
Recycled plastics: by recycling old plastic products, through the process of cleaning, crushing and remoulding, they are used again to produce new products.

Conclusion
Through the above analysis, we can clearly answer the question of “what material is plastic made of”: plastic is mainly made of synthetic polymers and various additives, processed through a variety of moulding processes. With the progress of science and technology, the development of environmentally friendly plastics is gradually changing our reliance on traditional plastics, and promoting the development of the plastics industry in a greener and more sustainable direction.