The Life Cycle of Plastic

We all know what plastic is, and we all use it. There is no getting away from this man-made material. In many ways, we have become reliant on plastic for our packaging, to store food, toys, plastic chairs, and dozens of more applications. However, as environmental concerns grow, looking at plastic's life cycle is helpful. Where does it come from, and what happens when we discard it?

We now know plastic is causing environmental problems, from animals ingesting it to depleting finite natural resources¹. There’s little doubt that switching to more sustainable and eco-friendly alternatives will prove vastly better for the planet.

Despite this, the demand is still due to plastics' cost, durability, and ubiquity. Further, most of us still get through a great deal of disposable plastic yearly, all contributing to mountains of plastic waste that must be dealt with.

Choosing Plastic-Free

We use it mainly because alternatives are less convenient or not widely available. And because consumer demand, although shifting, has yet to require manufacturers and retailers to change their ways. Despite the environmental costs, our supermarket aisles are still full of the stuff.

We can all make a difference in how much plastic waste we generate, however, by consciously looking for alternatives when we’re buying goods.

Simply making the choice to use eco-friendly straws or consider plastic alternatives such as bamboo will help. You can choose to say no to plastic bottles and when buying presents choose plastic-free. It's not just at home either; consider steps you can take to reduce plastic waste in the office.

Meanwhile, let's dive deeper into the entire life cycle of plastic to understand better where it comes from and where it goes at the end of its useful life.

Understanding the Life Cycle of Plastic - What is it?

Known as a man-made polymer, the life cycle of plastic begins when we make new plastic materials using several resources mainly derived from crude oil. We can create the polymer from several oil-based compounds, which we can manufacture into many shapes and variants. Across the world, we’ve created a huge volume of plastic. Estimates suggest that we have produced 8300 million metric tons of plastic⁸.

When you consider where we use plastic, we can see how versatile it is. It is certainly a flexible material, from plastic water bottles to car dashboards and plastic bags.

The History of Plastic

While we all know about plastic and use it, you might not know its back story. In terms of the materials that we use regularly, we could still consider plastic as being new.

Plastic’s history dates back to 1907, making it just over 100 years old. Leo Hendrik Baekeland invented plastic in 1907, then known as Bakelite. Unlike many plastics today, it was impossible to melt them then.

Therefore, it was a great electrical insulator, and its early uses included telephones and cameras. A couple of years later, in 1909, it became known as plastic.

Plastic has made it possible for us to make advances in many different areas, from flight to medical advances with the creation of self-disinfecting plastics to electronic devices. Innovative uses of plastic in medicine even help prevent infection⁵.

A wonder material in some ways, since the invention of plastics, it has played a key role in the growth of mass consumerism, providing many benefits that we now take for granted.

For example, a cucumber shrink-wrapped in the supermarket will last up to three times longer than its unwrapped counterpart. Accordingly, it allows supermarkets worldwide to extend the cucumber's shelf life alongside many other products. The result often helps to provide cheaper goods and a wider variety.

As such, plastic plays a vital role in the supply chain of many goods. Helping food last longer also helps reduce food waste. As with any argument, there are two sides to the story, and unnecessary plastic packaging is a scourge on our environment.

Read more: History of Plastic Use From Parkesine To Nylon.

How do we make Plastic?

We need raw materials such as oil and natural gas to make plastic⁶. The production involves taking some of the components of crude oil or natural gas and treating them. The trade calls this process the cracking process.

Following this process, manufacturers convert the components into hydrocarbon monomers. This can include ethylene and propylene. Further processing can help create additional monomers, such as vinyl chloride, styrene, and ethylene glycol.

The next step in the life cycle of plastic uses a process of chemical bonding. The monomers are bonded into chains that are known as polymers. Creating a combination of monomers makes it possible to manufacture a wide range of plastics with varying characteristics and properties.

Plastic Characteristics

When we consider how we use plastic, it is clear that it has many characteristics. We use it in plastic packaging, we use it to protect items in transport, and we use it to make window frames. It is a material that we can find in almost endless applications. Despite this, we can put the different types of plastic into two groups known as thermoplastics and thermosets.

Most of the plastics we know are thermoplastic. Therefore, once made, we can heat it and reform it as often as we wish³. Its ability to be reformed is crucial in the life cycle of plastic as it helps the recycling process and enables us to reduce the amount of plastic that we manufacture. In turn, it helps to reduce waste at the end of plastic's life cycle, CO2 emissions, and our reliance on natural resources.

The other main type of plastic, thermosets, cannot be reheated. Therefore, it cannot be reused and is almost impossible to recycle.

Next In the Life Cycle of Plastic: The Plastic Production Process

After the production of plastics in their basic form, it is possible to alter them depending on how they will be used.

At this point, many plastics have chemical additives blended with them. These additives change plastics' mechanical, chemical, and physical properties.

Improvements in additives now make plastic more adaptable⁹. This can make them heat-resistant, bacteria-resistant, or add color. They can also alter the surface appearance, allowing the plastic various applications.

We use plasticizers in those plastics that need a high level of flexibility or workability. This will help to create plastics such as flexible tubing or plastic wrapping. Plasticizers have been known to come with health risks, but new approaches help avoid these risks.

Making Plastic Products - The Processing Methods

Plastic products take many different forms. Depending on how we use it, plastic producers use different manufacturing methods. There are four main ways of manufacturing goods from plastic, and we use these to create the end plastic products that most consumers use.

Extrusion

This method involves the use of plastic pellets. These pallets get added to an extruder and melted using heat from the mechanical work and the hot wall of the machine. The molten plastic then gets pushed through an opening to create the desired product's shape. Manufacturers make plastic bags using the extrusion process.

Injection Molding

Plastic pellets get fed into a heating chamber. Once softened, they are placed in a cooled mold to become solid before it opens up to eject the product. A range of containers is made using this method, including butter containers and yogurt pots.

Blow Molding

We use this method alongside extrusion or injection molding. It consists of blowing the semi-molten plastic into a cooled mold, stretching, and pressing on the outer edge of the mold. We use this to create hollow plastic products such as milk bottles.

Rotational Molding

Here, we place plastic granules in a closed mold in a machine that rotates on two axes. Factories then heat the granules while the mold rotates, evenly distributing the plastic around the mold to create a coating. The resulting part then cools before being ejected. We use this process to create large toys or plastic furniture.

How Do We Use Plastic?

Plastic is a material that is important to us, regardless of how we look at it. Its versatility means that it has many uses, but why has it become so widely used?

The truth is that plastic is a cost-effective material, especially thermoplastic composites.  As such, the low costs enable manufacturers to meet consumer demand.

We can create a huge range of products and items from this flexible and adaptable material. Its ability to form many shapes and sizes makes it ideal for various industries. It essentially provides a quick and straightforward solution.

Later in the Life Cycle of Plastic: Reusing & Recycling Plastic

In some ways, the life of plastic is never-ending. It is a material that takes up to 100s of years to degrade, and we can recycle certain plastics. We can melt and reform thermoplastic almost indefinitely in some instances. However, in most cases, we can only recycle plastics several times before they become less usable.

However, our reliance on plastic is causing many problems. With over 300 million tonnes produced each year, our reliance is growing. This has meant that plastic has become a waste and environmental problem as well as a health problem due to the toxicity of some types of plastic¹⁰.

Finding new applications

At this point in the life cycle of plastic, most recycled plastic gets down-cycled. And almost all food-grade plastics. This means recycled plastics have a lower grade. From here, we can make plastic bins for picnic tables, for example, rather than other food packaging. However, it is also common to see textiles made from recycled bottles and toys.

Recycling thermoplastics is a process that requires thorough sorting. Often, it is not possible to mix different types of plastics.

This is down to how the different properties will separate during the process. If contaminated with different types of plastic, the resulting material is unusable as it is too soft. Therefore, sorting before recycling becomes particularly important.

To make it easier to recycle, we sort plastic into categories. We do this by using plastic identification codes. The different plastics are then taken to the correct recycling facility and ground into tiny pieces before being washed, dried, and heated. At this point, recycling facilities melt the result into pellets or transform them into the desired material.

The plastic life cycle then begins all over again.

Plastic That Isn’t Recycled

Despite efforts to increase plastic recycling, much of our plastic is not recycled. Estimates suggest that we actually recycle as little as 9% of waste plastic. Of the rest, 12% is incinerated, and the remainder ends up in landfills or the natural environment.

Neither of the last two options is optimal for the environment. Incineration releases C02 impacting climate change.

And landfills do not present a safe end to the life of plastic. Birds scavenge landfills, ingesting plastic. Loose plastic blows out of landfills and can eventually find its way into our waterways.

The result is that up to 12 million tonnes of plastic annually enter the ocean. Once plastic reaches the natural environment, the results can be devastating. Research shows that up to 700 species of marine life are affected by plastic⁷. And another study found that up to 1 million people die each year in the developed world due to diseases resulting from plastic waste⁴.

Plastic Lasts 100s of Years.

And because plastic takes 100s of years to break down, it will still be around far longer than our lifetimes. Due to the different types of plastics having different compositions, quite how long they stay with us varies.

For example, a paper coffee cup lined with plastic breaks down in around 30 years. On the other hand, 6 plastic rings commonly found attaching beer cans together will break down in around 400 years. Disposable nappies and glass bottles are around 450 years.

Ultimately, if we don't recycle plastic into new goods or incinerate plastic waste, it will last a very long time in landfills and the environment.

Further, plastic doesn’t biodegrade; it breaks down into smaller particles called microplastics. Even when plastic breaks down, these small particles will still be found in nature or awash in our Oceans. Researchers have even found microplastics in our water and glaciers², and concerns are growing as to their impact on human health.

Related: For a deeper dive, read our article on the environmental impact of plastic water bottles.

The Importance of Reusing and Recycling Plastic

Therefore, we all have a duty to reduce the amount of plastic we use. To help reduce plastics' environmental impact, we should all do our bit to prevent the manufacture of new plastics in the first place. If we were all to do so, simply reducing or eliminating our use of plastics would have a huge impact. And we can all start by changing what we buy and choosing plastic-free wherever we can.

Now is the time for us all to make a conscious effort to make a change. It is our responsibility to reuse plastic where possible.

We must all ensure we recycle and do our best to champion and implement the 4R principles of Refuse, Reduce, Reuse, and Recycle. This way, we can help to make the world a better place. As it stands, plastic is killing wildlife; we are using natural resources and generating harmful greenhouse gases.

Plastic has helped us achieve many things and has enhanced our lives. Despite this, the mountains of plastic waste in nature are a problem we cannot ignore.