The Ultimate Guide to PET Plastic

Polyethylene terephthalate, known to most as PET, is the most used thermoplastic polymer. You’ve probably seen the recycle triangle with the number 1 on many beverages and food containers, but that’s only the beginning of PET. If its scientific name or abbreviation doesn’t ring a bell, polyester might. The material is known to make most clothing and other furnishings articles. However, it starts as clear, strong, and lightweight plastic.

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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.

Physical PropertiesDensity1,3 – 1.4 g/cm3Water Absorprtion – equilibrium (%)less than 0.7

 

Thermal PropertiesUpper working temperature115 – 170⁰C

 

Mechanical PropertiesTensile Modulus (GPa)2 – 4

 

Processing PropertiesMelting Point260⁰C

 

Misconceptions of PET

Despite our interactions 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.

Pros

1. Polymers are easily available and inexpensive.
2. High strength-to-weight ratio.
3. Highly transparent and shatterproof
4. easily recycled.

Cons

1. Lower heat resistance.
2. PET resins are susceptible to oxidation.
3. Partially derived from crude oils.
4. Not biodegradable.

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 by 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.

PET

• Strength - high impact capability and shatter resistance.
• Better chemical resistance, impact resistance, and clarity.
• Typical applications - bottles.

PETG

• Strength - copolymerization keeps it from crystalizing and reduces cracking.
• Good chemical and impact resistance and clarity.
• Typical applications - Cosmetic packaging.

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 a 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, and 79% less energy, and has under a quarter of the carbon footprint of 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 is 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 materials 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 of 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 well-being. 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 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. 

Thermal Properties

Want more information on recycled pet plastic resins? Feel free to contact us.

Upper working temperature115 – 170⁰C

Lower working temperature-40 – -60⁰C

 

Processing Properties & Conditions

Melting point: 260⁰C

Drying Temperature: 120⁰C

Extrusion Temperature: 270-290⁰C

 

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 them and push them through; if it’s too big, not only may it not fit, but it may cause a blockage.

3. Drying

PET is hygroscopic, meaning that it absorbs moisture from the air. When extruding a material, moisture can affect the quality and texture of the filament. To dry your regrinds, you can either choose to use an industrial dryer or dry it in your oven at home! Once it’s dried and as much moisture as possible is drawn from the regrinds, you can start extruding. 

4. Extruding

Before extruding, you need to remember that there are different PET grades, and each filament extruder will require various changes depending on this. Experimentation is key here. We suggest testing out different temperatures in steps of 5°C while waiting in between to look at the tolerance. Once you feel confident in the set temperatures, it’s time to change the extrusion speed in increments of 0.5 RPM and the fan cooling temperature. 

Once you’ve extruded your filament, if you don’t plan on using it to 3D print immediately, then store it in a dry place or vacuum seal it to prevent it from drawing in moisture from the air. 

5. 3D Printing

Your rPET filament is now ready for you to print! Experimentation is the name of the game here, from extruding and continuing with 3D printing. Before going full speed ahead and printing the actual print you want to create, we suggest trying a smaller print. This way, you can see how your rPET filament will react. 

Some variables you should keep in mind are the temperature and printing settings. If you have too high of a temperature setting, your filament might melt too quickly, and your 3D print won’t be even. Here are general guidelines to which settings you should put your 3D printer, but, as mentioned earlier, every piece of hardware is different, and you might have to react to what output you’re receiving.

Nozzle size: ≥0.15mm Layer height: ≥0.1mm Flow rate: ±110%

Print temp: ±200 – 240⁰C Print speed: High Retraction: Yes ±6mm

Heat bed: ±65 – 75⁰C Fan speed: 0-30% Experience level: Beginner

Once you’ve tested out your printer with your rPET, you can create your final design! While there is a limit on the settings, there is no limit to how creative you can get with your 3D prints!

If you’re not into 3D printing or have access to the equipment necessary to reuse PET in this way, luckily there are countless projects that you can get started on to give it a new life.

How Can I Repurpose PET?

It can be easy to recycle PET at home, give it a new life, and enjoy the time as a creative outlet. PET can be recycled in multiple ways at home with various degrees of difficulty. Here are three projects which will help you recycle with it at home:

1. PET typically starts as food containers and can easily continue that path; reuse your coffee creamer bottles to store sugar, spice, and everything nice for minimal storage and an easier pour.
2. Keeping a plant alive can be tricky, but this craft will be just the incentive you needed to continue trying! Plant pots can be expensive in the long run and not as colorful as some of us may like. Turn your empty bottles into hanging planters and customize them by painting the outside with your favorite color!

3. Fight plastic waste with plastic waste! Turn your larger PET bottles into a plastic bag dispenser. Make it easier for yourself to collect something that is typically seen as a one-time use option, and use the plastic bags for varied uses! Start by gathering the bags you get from your grocery runs and use them as a trash can linings, storage bags, and the bags you continue to use for your grocery runs! If the bags show signs of wear and tear, you can decide to create gift bows for the final piece of a gift or make custom coin pouches. Like PET bottles, plastic bags have huge repurpose potential!

Hopefully, if you didn’t know before, you know now why PET is still one of the most used plastics. Its universality is shown as different products within one industry and through its versatility in various sectors. Not only can it be recycled and reused into a product with the same level of quality as the virgin product, but it is the most recycled plastic out there! These qualities enable it to contribute to a circular economy in ways such as return schemes. 

Its varying application forms and reusability make it an attractive material to extrude filament and 3D print with, all the while gaining valuable knowledge on its properties.

There are a handful of plastic resins used to make bottles and closures. Many bottles and closures are used to package prescription and over-the-counter medications, vitamins and supplements, and lifestyle products. At Drug Plastics, High Density Polyethylene (HDPE); Low Density Polyethylene (LDPE), Polyethylene Terephthalate (PET); and Polypropylene (PP) are used in our manufacturing process. In addition to these traditional options, we also offer two sustainable resins: Post-Consumer Recycled (PCR) HDPE and PCR PET. Each different resin type has unique properties which may or may not be advantageous for the product that will be packaged inside.

It’s important to know the characteristics of each resin type when designing and selecting product packaging. But how do you decide which plastic resin is best suited for the bottle used for your product? Our knowledgeable staff can help. Let’s review some of the key characteristics of each resin type.

High Density Polyethylene (HDPE)

HDPE is a thermoplastic polymer that is traditionally made from oil or natural gas. HDPE is one of the most versatile plastics and is used in a variety of applications, like plastic beverage bottles, plastic piping, and of course, plastic bottles for packaging pharmaceutical, nutraceutical, and lifestyle products. HDPE resin is translucent in its natural state; colorants are added during the bottle manufacturing process to change the color.

Bottles made with HDPE resin:

• Clarity: Are translucent and allow some light to pass through, but can achieve light block by adding colorant.
• Moisture Barrier: Have low permeability, meaning it is very effective in protecting products that are sensitive to moisture.
• Oxygen Barrier: Oxygen passes through easily, making it less effective in protecting products that are sensitive to oxygen.
• Rigidity: Moderate at retaining its shape under pressure.
• Impact Resistance: Excellent at avoiding dents and bruises.
• Heat Resistance: Good at withstanding heat up to 145 degrees F.
• Cold Resistance: Excellent at tolerating cold as low as -50 degrees F.
• Resistance to Sunlight: Fair at resisting breakdown from UV light.

Because of these characteristics, HDPE bottles are well-suited for many types of solid dose and liquid medications, vitamin capsules, gel caps, and lifestyle oils, tinctures, gummies, and more.

Post-Consumer Recycled (PCR) HDPE

Sustainability is now more important to consumers than ever before. For this reason, many companies rate sustainability as a key factor in selecting the materials they use for plastic packaging. To support this growing demand for planet-friendly packaging, we offer Post-Consumer Recycled (PCR) HDPE.

Although traditional HDPE bottles are easily recyclable and help to keep non-biodegradable waste out of landfills, PCR HDPE is more sustainable because it is made from 100% post-consumer recycled material. It eliminates plastic from the environment by converting HDPE plastic that is discarded by consumers back into resin that can be used again to make new products.

Bottles made with PCR HDPE:

• Retain similar properties, performance, and application versatility as traditional HDPE.
• Can package the same products that work well with traditional HDPE.
• Meet rigid standards for the pharmaceutical, nutraceutical, and lifestyle industries.
• Pass USP and ASTM testing.
• Are fully recyclable in the current HDPE recycle stream.

Use our PCR HDPE Sustainability Calculator to learn more about this planet-friendly alternative and see how simple changes can have a big impact on the environment.

Low Density Polyethylene (LDPE)

Like traditional HDPE, LDPE is also made from oil and natural gas. Any product that needs to be dispensed by squeezing the bottle is a good candidate for LDPE. Products like lotions, gels, and ophthalmic solutions work well inside LDPE bottles. Although there is very little difference in density between HDPE and LDPE, LDPE has considerably less strength when compared to HDPE.

Bottles made with LDPE resin:

• Clarity: Are translucent and allow some light to pass through, but can achieve light block by adding colorant.
• Moisture Barrier: Have moderate permeability, meaning it is effective in protecting products that are sensitive to moisture.
• Oxygen Barrier: Oxygen passes through easily, making it less effective in protecting products that are sensitive to oxygen.
• Rigidity: Low at retaining its shape under pressure, meaning it is easy to squeeze.
• Impact Resistance: Excellent at avoiding dents and bruises.
• Heat Resistance: Fair at withstanding heat up to 120 degrees F.
• Cold Resistance: Excellent at tolerating cold as low as -94 degrees F.
• Resistance to Sunlight: Fair at resisting breakdown from UV light.

Polyethylene Terephthalate (PET)

PET is part of the polyester family, and is known as the most common thermoplastic polymer resin. PET is commonly used to package liquid dose medications, like cough syrup, as well as vitamins and supplements. It is also a popular choice for lifestyle products in large part because PET can be made in a variety of colors while maintaining its transparent appearance.

Bottles made with PET resin:

• Clarity: Are clear and allow light to pass through, but can achieve light block by adding colorant.
• Moisture Barrier: Have high permeability, meaning it is less effective in protecting products that are sensitive to moisture.
• Oxygen Barrier: Oxygen does not pass through easily, making it a very effective barrier in protecting products that are sensitive to oxygen.
• Rigidity: High at retaining its shape under pressure.
• Impact Resistance: Excellent at avoiding dents and bruises.
• Heat Resistance: Fair at withstanding heat up to 120 degrees F.
• Cold Resistance: Good at tolerating cold as low as -40 degrees F.
• Resistance to Sunlight: Good at resisting breakdown from UV light.

Post-Consumer Recycled (PCR) PET

If your product performs well inside a PET bottle, PCR PET is a more sustainable option to consider. Like PCR HDPE, this resin is made from 100% post-consumer recycled material. In a circular economy, making new bottles from PCR PET removes plastic from the environment by converting plastic waste discarded by consumers back into resin that can be used again.

PCR PET helps reduce greenhouse gas emissions levels that are damaging our planet. PCR PET also retains similar properties, performance, and application versatility as its traditional counterpart.

Bottles made with PCR PET resin:

• Retain similar properties, performance, and application versatility as traditional PET.
• Can be used to package the same products that work well with traditional PET.
• Meet rigid standards for the pharmaceutical, nutraceutical, and lifestyle industries.
• Pass USP and ASTM testing.
• Are fully recyclable in the current PET recycle stream.

Use our PCR PET Sustainability Calculator to see how changing to PCR PET from traditional PET can help reduce your carbon footprint.

Polypropylene (PP)

Polypropylene is a type of plastic that is known for its semi-crystalline nature. It is a great choice for solid dose prescription and over-the-counter medications, creams and ointments, and powdered supplements. We use PP to manufacture our closures as well.

Bottles made with PP resin:

• Clarity: Are translucent and allow some light to pass through, but can achieve light block by adding colorant.
• Moisture Barrier: Have low permeability, meaning it is very effective at protecting products that are sensitive to moisture.
• Oxygen Barrier: Oxygen passes through easily, making it less effective in protecting products that are sensitive to oxygen.
• Rigidity: High at retaining its shape under pressure.
• Impact Resistance: Good at avoiding dents and bruises.
• Heat Resistance: Good at withstanding heat up to 165 degrees F.
• Cold Resistance: Fair at tolerating cold as low as 30 degrees F.
• Resistance to Sunlight: Fair at resisting breakdown from UV light.

Summary

All of the resins and raw materials Drug Plastics uses are FDA-approved, ASTM-tested, and made in the USA. We never source materials from overseas, providing our customers with the peace-of-mind knowing that their products will pass strict regulatory requirements.

A Trusted Partner for Your Packaging Challenges

Do you have a new product that needs packaging? Do you want to differentiate your brand with new packaging, or do you want to discuss resin options for an existing bottle? Work with us and you have access to over 60 years of manufacturing expertise. Our knowledgeable team can help you determine which type of resin and which bottle will work best for your product.

Our plastic bottles and closures are used all around the world. Put our trusted manufacturing and design experience to work for you and make the right decision for your product packaging. Contact us or speak with someone immediately at 610-367-5000.

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