Despite writing a wide variety of articles over the years we realized we’ve never touched on just how plastics are made, something we think is worth rectifying. Read on to learn about how plastics are created by technicians and to discover key insights about the plastic manufacturing process.
A Brief History of Plastics
The word “plastic” comes from the Greek “plastikos” which translates into “fit for molding.” Plastic gained this named due to the substance’s extreme malleability, which lets it be altered in a variety of ways, including through casting, pressing and extruding.
Its malleability also leads to it being suitable for an assortment of forms such as fibers, plates, films, bottles, tubes, and more.
Some of the key moments in the development of early plastics include the following:
- 1855 – Alexander Parkes invents “Parkesine,” one of the first plastic compounds. Today, we refer to it as celluloid.
- Mid-1800s – Polyvinyl chloride, also known as PVC, is first polymerized.
- 1907 – Chemist Leo Baekeland creates “Bakelite” which goes on to become the first synthetic plastic produced on a mass scale.
Following these major milestones, a wide variety of plastics have been developed and introduced to the public, with the industry really coming into its own following the increase in material availability after World War II.
How Are Plastics Made?
Plastics, or polymers, are created by converting natural materials or by synthesizing primary chemicals. Elements that commonly make up plastics include:
These elements originate from materials that include:
- Natural gas
- Crude oil
Crude oil is one of the major sources, and for it to be utilized in plastic manufacturing the material needs to be distilled into lighter components known as fractions. Every fraction is a mixture of hydrocarbon chains, with the fraction known as “naphtha” being an essential component for the manufacture of plastics.
The majority of plastics are based upon the carbon atom, though some are based upon the silicon atom. Carbon can link to other atoms with up to four chemical bonds, making it extremely versatile.
Types of Plastics
There are different ways to classify plastics, but one of the key ways they are delineating is in the categories “thermoplastics” and “thermosets.”
- Thermoplastics – These are plastics which are the results of polymers that have atoms which have bonded to form long chains. One key aspect about thermoplastics is that they are meltable, which means they can be formed into a product then later melted down to be reformed into a new product. This can be done many times over leading to thermoplastics’ popularity, as roughly 92% of all plastics are of this type.
- Thermosets – These are plastics which are the results of polymers that have atoms which form two- and three-dimensional networks. The key aspect about thermosets is that they are not meltable, leading them to be used in a variety of adhesives and other mixtures which then “set up.” These plastics never soften again once they have been molded, so they cannot be easily recycled except for use as filler material.
Examples of thermoplastics include:
- Polyvinyl chloride (PVC)
- Polycarbonate (PC)
- Acrylonitrile butadiene styrene (ABS)
- Expanded polystyrene (EPS)
- Polymethyl methacrylate (PMMA)
- Polyethylene (PE)
- Polypropylene (PP)
- Polyethylene terephthalate (PET)
- Polystyrene (PS)
These types of plastics are often utilized for:
- Plastic bottles
- Carpet fibers
- Electrical insulation
- Car parts
- House siding
- Coverings for electrical equipment
- Floor and wall coverings
Examples of thermosets include:
- Polyurethane (PUR)
- Epoxide (EP)
- Unsaturated polyester resins (UP)
- Phenol-formaldehyde (PF)
- Polytetrafluoroethylene (PTFE)
These types of plastics are often utilized for:
- Electrical appliances
- Circuit boards
- Bath tubs and showers
- Boat hulls
- Helicopter blades
Beyond their thermoplastic and thermoset classifications, plastics fall into the following categories:
- Epoxy Resins – These materials are often used as linings or protective coatings for a variety of products, and have been incorporated into paints as well.
- Bio-based Plastics – These products are made in part or whole from renewable biological sources, such as starch and sugar cane.
- Engineering Plastics – These materials are ideal for a diverse range of applications due to their weight/strength ratio, ease of production, and ability to form complex shapes.
- Biodegradable Plastics – These plastics have the ability to be degraded by microorganisms into water, biomass, and carbon dioxide.
- Polyolefins – Made from oil and natural gas, these diverse plastics have become one of the most widely-used types of plastic available today.
- Expanded Polystyrene – Many everyday products utilize this product due to its extreme versatility. You come across it often when you order a package, by way of packing peanuts.
- Polystyrene – These polymers are often formed into films or sheets for use in a range of products.
- Fluoropolymers – This type of plastic is considered high performance, with PTFE being the most well-known subset. PTFE us actually considered the most slippery material in existence which is why it’s regularly used for aerospace applications, electronics, industrial machining, and more.
- Polyurethanes – These sturdy and malleable plastics are often utilized within products as protectants or padding.
- Polyvinyl Chloride – This plastic, also known as PVC, is the third-most produced synthetic plastic polymer in the world.
Attributes and Uses for Plastics in Manufacturing
Now that we’ve covered some of the key points on how plastics are made, let’s delve into some of the core benefits of plastics and why plastics manufacturing is so vital to the economy and the world at large.
- Low Density – Because plastics are low in weight and density, and because their weight/strength ratio can often be relatively high compared to other materials, they are particularly suited for any application where quality and functionality needs to be maintained but cost is a factor.
- Electrical Capabilities – Most plastics are particularly good as components of insulation materials, though certain forms are also able to conduct electricity should that functionality be desired.
- Corrosion Resistance – Because plastics are resistant to corrosion compared to many other alternatives, they are well-suited for harsh environments.
- Malleability – Since plastics can be molded into an endless array of shapes, virtually every industry can find a use for them.
- Transparency – As some plastics are transparent, or can made to be transparent, plastics’ functionalities increase even more, especially in regards to electronic equipment such as CDs, DVDs, and Blu-ray discs.
- Versatility – With the numerous plastics available to companies, should any one not meet all needed requirements, various options can be merged to create the desired result.