Understanding Plastics: Properties, Origin, and Recycling

What are Plastics?

In chemistry and technology, plastics are polymeric organic materials. They are giant molecules formed by carbon atoms linked with hydrogen, oxygen, and to a lesser extent, chlorine, fluorine, nitrogen, or silicon.

Key Properties of Plastics

• Affordable
• Low density
• Waterproof
• Electrical insulators
• Thermal insulators, although not highly resistant to heat
• Resistant to corrosion and weathering
• Resistant to many chemical factors
• Some are recyclable, but not all are biodegradable or easily recycled
• Easy to work with
• Burning some plastics can be highly polluting

Origin of Plastics

Polymers can be classified based on their origin:

• Natural: Occur spontaneously in natural products like cellulose, rubber, and casein.
• Artificial: Industrially obtained by modifying natural polymers, such as celluloid, ebonite, and galalite.
• Synthetic: Industrially produced from their basic components, including polyethylene, polypropylene, PVC, and nylon.

Manufacturing Plastics

The initial stage of plastic production involves creating polymers in the chemical industry. Today, post-consumer recovery is also crucial. The production process concludes by shaping the plastic or resin, typically in granular form. Common methods include molding (injection, compression, rotational, inflation) or extrusion to create profiles or wires, ensuring optimal results.

Consolidation of Plastics

There are various types of plastics. To classify them, an encoding system is used, as shown in Table 1. Products carry a mark, the international symbol for recycling, with the corresponding code based on the specific material.

Recycling Plastics

Plastic is a recyclable material. Many countries have implemented plastic recycling programs with designated containers.

Table 1: International Coding for Different Plastics