Thermoplastics are one of two main types of plastics on the market today (with thermosets comprising the other major category). Thermoplastics are unique in that their polymer bonds allow them to be heated and remolded indefinitely, making them highly recyclable, while thermosets feature permanent chemical bonds that harden after a single heating, more or less preventing heating and remolding.
There are several different types of thermoplastics. You’re probably familiar with thermoplastics like acrylic, nylon, PVC, and Teflon, for example. How are the plastics in this category made? Are there differences between how one type of thermoplastic is produced versus other varieties?
How Are Thermoplastics Made?
By their very nature, thermoplastics can be heated and remolded again and again, depending on their chemical makeup, which means they can be “made” in a variety of ways. These plastics have to come from somewhere, however, and they typically start as components that are combined to create granules, which can be manipulated with heat and molded into products.
Thermoplastics can come from both natural and synthetic sources. For example, some thermoplastics are made from cellulosics, or cellulose fibers found in wood and cotton. Nylon, acrylic, and polyester come from petrochemicals, including petroleum- and plant-based materials.
Granules are created when the base material is heated, desired additives like dyes are mixed in, and the mixture is cooled and separated into small particles that are easy to package and transport. From there, manufacturers can reheat granules, add desired chemicals, and mold them in different ways to create a wide range of products.
Differences In Thermoplastic Manufacturing
There are a few different ways thermoplastics can be molded into desired shapes or configurations, including extrusion, injection molding, and thermoforming.
- Extrusion involves passing heated thermoplastic material through a die, or steel disk, before pressing and cutting it to create desired shapes.
- Injection molding, as the name implies, involves injecting heated thermoplastic material into a mold and allowing it to cool and harden into the prescribed shape.
- Thermoforming involves heating sheets of thermoplastic and forming them in or over molds, allowing them to cool, and then trimming away excess material.
The type of production used may depend on several factors, including the type of thermoplastic being used, the product being created, and the preferences of the manufacturer. Ultimately, thermoplastics that remain unpolluted by chemical additives have the best chance of being heated, remolded, and made into new products during the recycling process.