Polyethylene Terephthalate Glycol: The Versatile Polymer

What is PETG?

PETG, also known as polyethene terephthalate glycol, is a thermoplastic polyester with excellent chemical resistance, durability, and formability in industrial applications. Polyethylene terephthalate (PET) is modified into PETG (Polyethylene terephthalate) by the molecular addition of glycol, denoted by the letter ‘G’, to provide new chemical characteristics. Although PET and glycol-modified PETG both contain the same monomers, the latter is far more robust, suitable for usage in higher temperatures, and impact-resistant.

Polyethylene terephthalate glycol is widely used in a wide range of consumer and industrial applications because it can be easily vacuum and pressure-formed or heat-bent at low forming temperatures. Because of these characteristics, it is also a popular material for 3D printing and other forms of heat moulding. PETG is very easy to work with within a variety of other processes like bending, die cutting, and routing.

When Does It Come?

The discovery and development of polyethene terephthalate (PET) are crucial to comprehending the manufacturing process of PET glycol.

In the middle of the twentieth century, scientists made significant discoveries in polymer chemistry, opening the door to the possibility of using synthetic materials in place of more conventional organic ones. Synthetic fibres derived from glycol were employed in textile production, whereas phthalic acid polymers were used in paints and varnishes. Both the phthalic acid products and the glycol-based polymers exhibited melting temperatures that were too low to be employed as fibres in textiles.

Polyethylene terephthalate (PET) was created when British scientists John Whinfield and James Dickson mixed these chemicals in 1941. By heating glycols in the presence of terephthalic acid, they were able to produce long-chain molecules of PET, which could then be spun into fibres with high melting temperatures and low dissolvability. In 1946, PET was first used in textiles, and by 1952, it had also been adopted as a film for food packaging. In 1976, PET was utilized to make hard bottles that could hold carbonated liquids including soda, beer, and mineral water without breaking. Although it is one of the most popular plastics used today, PET has significant drawbacks, such as its tendency to crystallize at high temperatures. The PET becomes cloudy and its integrity is compromised.

To prevent the crystallization of polyethene terephthalate (PET), scientists developed PETG by replacing the ethylene glycol in the molecular chain with a bigger monomer, cyclohexane dimethanol. Due to its increased resilience to heat, PETG has a lower melting point and is less prone to crystallization than PET. 

This means that polyethene terephthalate glycol can be utilized in high-temperature processes like thermoforming and 3D printing without degrading.

For What Purpose Is It Used?

Due to its resistance to heat, shock, and chemicals, PETG finds use in many different fields. It finds extensive application in a variety of industries, including retail and medical packaging, promotional displays, and electronic insulators.

Glycol inhibits PET from overheating, clouding, and breaking down, making it a popular choice for 3D printing. PETG products can also be sterilized. PETG is quickly becoming the material of choice for 3D printing due to its strong layer adhesion, low deformation during printing, tolerance at low temperatures, chemical resistance against bases and acids, and lack of odour during printing.

To make pressure-clad objects, protective parts, or food containers that are both flexible and shock-resistant, polyethene terephthalate glycol is the material of choice.

Is it safe for the planet?

Landfilling PETG can take decades, however recycling it is simple thanks to chemicals that break down the polymer strands to their constituent parts. These parts can then be repurposed as building blocks for brand-new polymers.

Recycling plastics back into production significantly reduces the consumption of natural resources, as the production of new plastics requires a lot of energy and water. To further protect marine life, recycling keeps PETG products from decomposing into tiny particles that would otherwise enter the water supply and damage the oceans.

The environmental impact of polyethene terephthalate glycol, like that of all plastics, can be mitigated or eliminated thanks to its capacity to be recycled.

Properties

PETG, a copolymer, shares characteristics with both PET and glycol. The overheating problems of PET are mitigated by this combination.

Polyethylene terephthalate glycol is notable for being tough, chemical and impact-resistant, see-through, and ductile. PETG is a food-safe plastic that is easily extrudable and has high thermal stability. The extrusion temperature of polyethylene terephthalate glycol is between 220 and 260 degrees Celsius, and the print speed is between 40 and 60 millimeters per second.

Despite its many advantages over other 3D printing materials, PETG cannot be printed without a heating plate, much like ABS, and it scratches more easily than PLA. The maximum safe temperature for a heating tray is 80 degrees Celsius. PETG has a sticky look, making it challenging to remove printing supports.

PETG readily absorbs moisture and benefits from being stored in a cool, dry place.

Advantages

When compared to materials like acrylic and polycarbonate, polyethene terephthalate glycol has a number of advantages. Among these benefits are:

1. Durable and low-cost glazing

and robust display units are two applications that benefit greatly from PETG’s robustness and impact resistance. It works wonderfully for making models, exhibits, and signs using 3D printing technology.

2. Recyclable and safe for use with food

PETG can be used in the construction of beverage and food containers without risk. In addition to minimizing waste and the potential for severe environmental effects, it is recyclable. 

3. Formable

PETG can tolerate high pressures without cracking and can be formed using either a vacuum or heat. It is versatile and may be formed into many different forms by injection moulding or extrusion.

4. PETG’s inherent transparency

makes it ideal for special effects, and the material’s versatility makes it simple to colour and combine for a wide range of aesthetic possibilities.

 5. Emissions that are safe and odourless

3D-printed objects made from PETG are safe for use in both the home and the workplace because they emit no hazardous or offensive fumes.

Disadvantages

While there aren’t many drawbacks to employing polyethene terephthalate glycol, caution is still advised, especially when setting temperature conditions.

1. Specific Guidelines Must Be Adhered To

Using the right temperature parameters is essential for successful 3D printing with PETG. Extruder temperatures of 210-260 degrees Celsius and base temperatures of 60-80 degrees Celsius are typical, although a cold base can be used instead. While the ideal settings for your 3D printer are being determined, we advise printing at a slow speed of 30 to 35 mm/s.

2. Easily Bleeding

You’ll need to play around with the bridging and retraction settings on your 3D printer if you’re using PETG because it oozes more than PLA or ABS. Therefore, additional post-processing to fix imperfections might be needed.

3. More brittle than usual

If improperly stored PETG absorbs water if not kept in a dry environment.

4. Environmental Concerns

If not disposed of correctly, PETG can have the same harmful effects on the environment as other plastics. Decomposition can take decades, and in the meantime, microplastics are released into the oceans. These environmental concerns are mitigated, however, because PETG is easily recyclable.

Methods of Manufacturing

Two-step, melt-phase polycondensation is used to create PETG. Two monomers can be joined together by this simple procedure, with the byproduct often being a tiny molecule like water.

PETG can be extruded as a filament for 3D printing, injection moulded, or shaped into sheets. This procedure also allows for the dyeing of this transparent amorphous thermoplastic.

Applications

Polyethylene terephthalate glycol’s characteristics make it useful in a variety of contexts, such as:

 Beverage and Food Carriers

Cooking oil containers, water bottles, and FDA-compliant food storage containers are just some of the many commonplace goods made from PETG due to the material’s high chemical resistance and ease of thermoforming. Lightweight and strong, it offers benefits in terms of both distribution costs and efficiency, making it a popular choice for packaging cosmetics.

Uses in Medicine and Pharma

PETG is appropriate for use in medical implants and packaging for pharmaceutical and medical device products due to its robust structure and resistance to rigorous sterilizing treatments.

Stands and Displays for Retail Shops

Point-of-purchase retail displays frequently incorporate polyethene terephthalate glycol. It’s great for use as a sign because it can be coloured.

Machine Safeguards, 

Machine guards can also be made out of PETG. The transparent plastic is flexible and safe for use. Because PETG guards are more malleable than polycarbonate and more robust than acrylic, they find widespread application in the food processing industry.

Three-Dimensional Printing

As was previously noted, PETG has become increasingly popular for use in state-of-the-art 3D printers. Printing with a polyethylene terephthalate glycol filament is simple and the resulting layers stick together well. PETG is a durable, chemical-resistant, and odourless printing material with low shrinkage rates that enable larger prints than PLA or ABS. It is recommended to utilize a cooling fan when printing with PETG, and laying down a layer on the build plate can solve issues with print bed adhesion.

What’s Next for PTEG

Although there is a continual need to ensure recycled PETG resources, the future of polyethene terephthalate glycol is bright as the worldwide market continues to develop.

Conclusion

Polyethylene terephthalate glycol (PETG) is a widely used plastic having superior qualities to those of other plastics. PETG is widely utilized in the food and medical industries and is seeing growing adoption in 3D printing applications.

Video 01: PCTG, Polyethylene Terephthalate-Glycol 3D Printing Filament from Essentium