Plastic is one of the most versatile products on the planet today. Manufacturers and plastic recycling companies make millions of dollars developing and repurposing plastic to make new products that people use every day. In fact, about 200 billion pounds of plastic is recycled into millions of packages and products every year. But how is plastic made originally, and how is it recycled?
Making Plastic
To make plastic, chemical engineers and manufacturers start with raw materials to develop monomers, or a molecule that bonds to another identical molecule to form a polymer. These materials include chemicals such as ethylene and propylene, which are obtained in oil and gas refineries. Once engineers have these items, they are chemically processed to make hydrocarbon monomers and other types of carbon monomers used in plastics.
These monomers are put together in polymerization plants to become three dimensional networks and polymer resins which are further processed to create plastic resin pellets, beads, or final plastic products. They are heated, molded, and cooled, which can involve a few different processes depending on what product is being made.
- Extrusion is used to make plastic films. During this process, pellets are heated and combined in a long chamber, pushed through an opening, and cooled with air/water.
- Injection molding is performed to make containers for foods such as butter and yogurt. Plastic resin pellets are heated, mixed in a chamber, and then highly pressurized into a cooled mold.
- Blow molding is typically used to make plastic bottles. During this process, pellets are heated and squeezed into a tube. Then, the resin is put into a cold mold, and compressed air is pushed into the tube where it expands against the walls of the mold.
- Rotational molding creates toys, furniture, sports equipment, and more. Resin pelleted are heated and put in a mold to cool that can rotate in three dimensions. This process evenly distributes the plastic throughout the mold.
These processes make it possible for plastic recycling companies to take items such as plastic films, containers, and bottles, melt them down, and create something new.
Recycling Plastic
This process depends on which of these items you are recycling, but usually includes shredding, washing, melting, and creating plastic resin pellets in two steps. In step one, contaminants are automatically or manually sorted out of the plastic waste stream. Step two involves melting down the plastic directly into a new shape, or shredding the plastic finely into flakes, then melting them down into granulates for reuse. Plastic recycling companies provide important household items such as furniture, flooring, materials for decks, and much, much more.
