What kind of material does plastic belong to?

Plastic is an indispensable material in our daily life and it permeates almost every aspect of our lives. What kind of material does plastic belong to? From a chemical point of view, plastics are a kind of synthetic polymer materials, whose main components are made up of organic polymers. This article will analyse in detail the composition and classification of plastics and their wide application in various industries.
1. Composition and chemical structure of plastics

To understand what materials plastics belong to, the first need to understand its composition. Plastic is generated through the polymerisation reaction of macromolecular substances, mainly composed of carbon, hydrogen, oxygen, nitrogen, sulfur and other elements. These elements form long chain structures, known as polymers, through covalent bonds. Depending on their chemical structure, plastics can be divided into two main categories: thermoplastics and thermosets.

Thermoplastics: These types of plastics soften when heated and return to their original form when cooled, and repeated heating and cooling does not change their chemical structure. Common thermoplastics include polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC).

Thermosetting plastics: Unlike thermoplastics, thermosetting plastics will undergo chemical cross-linking after the first heating, forming a three-dimensional network structure that is neither soluble nor fusible, so once moulded, they cannot be deformed by heating again. Typical thermoset plastics include phenolic resins (PF), epoxy resins (EP), and so on.

2. Classification and application of plastics

According to their properties and applications, plastics can be divided into three categories: general-purpose plastics, engineering plastics and special plastics.

General-purpose plastics: such as polyethylene (PE), polypropylene (PP), etc., are widely used in packaging materials, household goods and other fields. They are characterised by low cost, mature production processes and are suitable for mass production.

Engineering plastics: such as polycarbonate (PC), nylon (PA), etc. These plastics have excellent mechanical properties and heat resistance, and are widely used in automobiles, electronic and electrical appliances, mechanical parts and other demanding fields.

Speciality plastics: such as polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), etc. These materials usually have special chemical resistance, electrical insulation or high temperature resistance, and are used in aerospace, medical equipment and other high-tech fields.

3. Advantages and Challenges of Plastics

Plastics play an irreplaceable role in modern industry due to their light weight, high strength and easy processing. The use of plastics also brings environmental challenges. As plastics are difficult to degrade, waste plastics have a serious impact on the environment, so the recycling and reuse of plastics has become a global concern.
In industry, researchers are developing new biodegradable plastics with a view to reducing the environmental hazards of plastic waste. Technologies for recycling plastics are also advancing, and these technologies are expected to significantly reduce the cost of production of plastics and environmental pressures.

Conclusion

Plastic is a kind of polymer material made up of organic polymers, which can be classified into thermoplastic and thermosetting plastics according to different chemical structures and application areas. With the development of technology, the types and applications of plastics are expanding, but the environmental problems they bring cannot be ignored. Understanding what materials plastics belong to will not only help us to better apply this material, but also promote us to explore its role in sustainable development.