The Ultimate Guide to PET Plastic

What is PET Plastic?

PET has been around since the 1940s when chemists experimented with polymers to create textiles. The plastic’s popularity grew through the 1950s when researchers found a way to stretch PET into a thin sheet, this form being used mainly for video, photo, and packaging films. When the technology for blow-stretch molding was developed in the early 1970s, PET found a new form and its most notable use, PET bottles. Patented in 1973, PET bottles, compared to its container-predecessors (glass bottles, steel, and aluminum cans), were lightweight, safe, cheap, and recyclable. 

Properties of PET

By looking at a polyethylene terephthalate property table, we can understand and gain insight into how it would be working with PET plastic. While there are many variables at play, below, you will find a general material overview. Properties may vary slightly as there are different grades available.

Misconceptions of PET

Despite us interacting with PET daily, any mention of “PET” or “plastic” comes with a sense of taboo. We’ve associated the destruction of our climate with plastic waste. If you’re not picturing a polar bear surrounded by melting ice when “climate change” is mentioned, you’re probably imagining a sea of plastic floating in our oceans.

While PET is the most used plastic, it is also the most recycled. In 2017, 1.923 million tonnes of PET bottles were collected in Europe for recycling, seeing an increase of 2.9% from the previous year. In addition to that, the PET recycling rate was around 58.2%. Besides thinking of PET as one of the culprits behind plastic pollution, a thought that crosses many people’s minds is PET’s harm to our health.

It is essential to acknowledge that many governments worldwide have agencies regulating and providing scientific advice on any risks associated with foods and beverages. PET has been approved by the Food and Drug Association, Health Canada, the European Food Safety Authority, and countless more as safe for contact with food and beverages. While antimony oxide is used during the making of PET, it is only over more extended periods of exposure to heat that trace amounts of antimony may migrate into the beverages bottled in PET. These antimony levels are far below the safety thresholds, and the small amounts that might be found in PET contained foods and beverages are not anything to be concerned about as it does not pose any health risk.

If you still feel hesitant, check out your local food and beverage agency’s requirements on the use of PET containers for edible products.

The Pros and Cons of PET Plastic

Despite the many uses of PET and its popularity, there are certain limitations to it. Below we’ve compared the most common pros and cons when working with PET plastic.

PET vs PETG

Although PET is available as a homopolymer (a polymer where every monomer unit of the chain is the same), you can alter it to produce copolymers (a polymer derived from more than one species of monomer) desirable for specific applications. A known copolymer of PET is PETG, which is polyethylene terephthalate glycol-modified. One of the biggest misconceptions, especially in the 3D-printing filament industry, is that PET and PETG are the same. Unfortunately, this is not the case. PETG isn’t made from simply adding glycol to PET. PETG is formed during the initial polymerization process, where monomers/other components are combined to build the polymer up. Below you can see a table of the differences between the two.

How Is PET Used?

Besides food and beverage containers, PET is a known and familiar material used to create clothing, furnishing, textiles, and more in its polyester form. Famous for its durability and resistance to many chemicals, it retains its shape well and is easy to look after. Besides its use for consumables and wearables, polyethylene terephthalate has been used by the music and marine vessel industries and as fabrics for conveyor belts and fabric coating.

The most common application done with PET is injection molding. Injection molding is the manufacturing process for producing various parts by injecting molten material into a mold and rapidly cooling it off. Once molten PET gets injected into pre-form molds, they can then be blow-molded to create the desired shape after cooling off. We typically see this when making PET bottles, but this same technique is beneficial when producing shampoo bottles, trays, and watering cans. 

A lot can be done with PET, given its universality, but what we’ve mentioned is just the beginning. 

Industrial Use of PET

Thanks to its excellent electrical insulating properties, PET plastic is widely used in the electrical and electronics industry. PET has replaced die cast metals and thermosets within electrical encapsulation, solar junction boxes, and smart meters, to name a few. Considering its thermal range and its lightweight, PET plastic is mechanically strong; this reason, next to its design freedom and other advantages, has made it a popular material for the automotive industry. Its high abrasion and UV resistance, high stiffness, and low cost make PET very attractive to use throughout an automobile. 

Seat belts and seat covers require high abrasion and UV resistance to secure safety and comfort while in a vehicle. With its high abrasion resistance and durability, polyester is used in automobile carpets; alongside being durable against soil, it provides noise insulation. These factors are also why polyester is a commonly used material within the fashion, textile, and home furnishing industries. Polyester fiber is great as insulation material in pillows, comforters, and upholstery padding. The high stain and tear resistance make it an attractive material for clothing, with additional offerings in fewer wrinkles and shrinkage (compared to cotton). 

At Fontys University of Applied Sciences, one of the largest and most prominent educational institutes in the Netherlands, the Natural Science wing is one of the only to offer bachelor courses in polymer studies. 3D printing is part of their research facility; it assists students in researching and enhancing existing polymers. Through filament extrusion, students and researchers have been able to study the properties and recyclability of PET. 

While Fontys’ students and researchers extruded PET filament, for those who want to go straight into 3D Printing, PET filament is available and accessible. Ultra Fuse FFF provides PET filament, which is as easy to use as PLA but more durable. With different colors to choose from and a sustainable option, you’re sure to find just what you need for your 3D printing projects. 

In a time where sustainability is needed in all industries, Freudenberg Performance Materials, a leading global supplier of innovative technical textiles, has found a way to benefit from PET recycling. The supplier from Germany has been able to give PET a second life by making nonwoven materials to seal roofs. Using recycled PET in this innovative way proves that PET shows a lot of promise in its use as virgin and recycled material.

Can PET Be Recycled?

Recycling and reusing go beyond DIY projects at home; from being one of the most recycled plastics, PET has been given new lives within various uses and industries, mainly through becoming rPET.

Unlike PETG, where PET is glycol-modified, rPET means “recycled PET”. Bottles, containers, and other PET items collected and sorted go through shredding and drying, where then rPET is born and can be made into products such as blankets, insulation, car parts, clothing articles, and more! 

Although there is a limited global supply of rPET, there is a growing demand. This ever-increasing demand is seen in return bottle schemes; alongside this, the EU stated that by 2030, 90% of all PET products should get collected and reprocessed. Next to that, all newly produced bottles should include 25% rPET. The growing demand for rPET and the change in legislation to have rPET more commonly used are great facts when looking at how much environmentally friendlier rPET is to its predecessor. rPET uses 71% fewer greenhouse emissions, 79% less energy, and has under a quarter of the carbon footprint of the virgin material.

There are, however, two drawbacks that we should mention when comparing the two plastics. rPET can have a slightly different hue to PET due to impurities; however, using a mix of the two can quickly correct this. The other one being that rPET is more expensive than PET as high-quality granulate is in a lower supply. 

Aside from the economic and environmental factors, the recycled and virgin material are the same: they are both shatterproof, lightweight, and approved by various food and beverage agencies as being suitable for food, health, and home care products.

3D Printing and Recycled PET

If you’re looking for other ways to take control over your plastic waste, 3D printing filament could be an option. Through 3D printing, you have full control to create whatever you’d like.

The Extreme E racing series is the first sport conceived with concern for the climate crisis. By using electric racing in remote environments facing the threat of climate change, the series’ goal is to highlight and encourage all of us to take action to protect our planet’s future and wellbeing. That is why, while en route to their racing locations onboard St. Helena, the team will collect ocean PET, process it, and make it into filament, which will, in turn, be used to 3D print the winning teams’ trophies. Not only does this show how there are endless possibilities when working with rPET, but it is also a great example of closed-loop recycling. 

It might sound as easy as home projects when you want to move into the 3D printing possibilities of rPET, but you have to be aware that trial and error will occur; this is something we learned the first time we experimented with creating filament from rPET. It ended with several trial runs that resulted from adjustments made throughout, but it is doable! Since then, we’ve learned a lot about what it takes to create 3D printable filament from recycled PET, and have been successfully able to do so.

Be warned, patience is required.

How Can PET Be Applied in 3D Printing?

Earlier, we listed some of PET’s properties, but some properties and variables will be more of an interest to you when you want to extrude and create PET filament. Aside from the physical and mechanical properties listed earlier, thermal and processing properties are fundamental here.

An important reminder, however, is that the processing properties may differ depending on your PET manufacturer. That’s why we suggest following the guidelines given to you by them and being aware that depending on the hardware you’re using to extrude the filament, you may have to adjust the different variables as the settings you use on one extruder might not work on another. Processing properties are more “applied” and “hands-on” than other properties, and you’ll have to work and change as you go. 

5 Steps To 3D Printing With PET

Now that we know which properties we should pay attention to, we can get into the steps you’ll need to take to repurpose PET into a 3D print successfully.

1. Prepping Your PET

Before getting your PET products to a size that can go through an extruder, you need to morph it into a shape that can go through a shredder. There are three approaches you can take with this Crushing it with your hands, so it’s narrow enough to feed through a shredder. Use a vacuum to vacuum out the air and deflate the plastic. Cutting your material with scissors into smaller and more manageable pieces.

2. Shredding

The best solution is to use a shredder to get your PET plastic into more refined pieces (smaller than 4mm). This process is faster than if you were to continue cutting with scissors. To extrude the regrinds, they have to be small enough for your filament extruder to melt it and push it through; if it’s too big, not only may it not fit, but it may cause a blockage.

Recycle and Create! Get the GP20 Plastic Shredder Now!

Turn PET plastic into 3D printing gold! Get our Plastic Shredder to unlock limitless possibilities and innovate today!

Explore Shredder