PETG: A CLOSER LOOK

origins of petg

how it was first created

The mid-20th Century saw a revolution in polymer chemistry as scientists discovered how to produce new materials that could replace traditional organic sources. Polymers of phthalic acid were already being used in paints and varnishes but they were too soft and soluble to be used as fibers. Similarly, glycol-based synthetic fibers had low melting points that made them useless as textiles.

In 1941, British scientistsJohn Whinfield and James Dickson found they could combine these two substancesto create polyethylene terephthalate (PET or PETE). They heated glycols with terephthalic acid in a process of esterification to create long-chain molecules of PETE that could be turned into fibers with high melting points and that did not dissolve easily. PETE was commercialized in fiber form under brand names like Dacron and in film form as Mylar.

How it's made today

PETE’s properties have made it among the most commonlyused plastics today, but it does have some disadvantages. At high temperatures, crystallization turnsa PETE-based object opaque and weaken its structure.

Polyethylene terephthalate glycol-modified, or PETG, stops the crystallization by replacing ethylene glycol in the molecular chain with a larger monomer, cyclohexane dimethanol.The new structure prevents PETG molecules from collecting together as readily as PETE, lowering its melting point and inhibiting crystallization.

As a result, PETG can withstand high-temperature processes like thermoforming or 3D printing without losing its properties. Resistant to impacts, heat, and solvents, PETG has applications in many industries. You will find PETG in retail packaging, medical packaging, advertising displays and used as electronic insulators.

EASILY RECYCLABLE

The high volume of containers made from PETE makes recycling the plastic very economical. On the largest scales, recycling companies can use a chemical process to break the PETE polymer chains back into its original glycol and terephthalic acid components. Plastic manufacturers can then use these components as raw materials to produce new PETE.

More commonly, however, plastics recyclers grind used PETE into flakes to be sold to manufacturers as feedstock. However, the potential for contamination means this PETE cannot be used for food or medical applications.

Although just as recyclable as PETE using the same techniques, PETG’s lower melting point means PETG and PETE cannot be processed together.Some facilities have the technology needed to separate the two plastics, but others will send PETG to landfills with ABS and other plastics.

Environmental
Impact of PETG

Saves Landfill Space

Almost 20% of the trash dumped into landfills consists of plastics – everything from beverage bottles to shopping bags to retail blister packs. Taking the time to separate plastics from everyday trash and send them to recycling centers extends the life of landfills and lowers the cost of waste disposal.

saves Natural Resources

Recycling plastics benefits the environment far beyond the landfill. Producing fresh plastic requires a huge amount of energy and water. On top of that, many plastics derive from petroleum. Feeding used plastics back into the production process helps reduce the consumption of fossil fuels and other natural resources.

Decreased Pollution

Whether buried in landfills or tossed across the landscape, unrecycled plastics pollute the environment for decades. They degrade into microscopic fragments that are carried into oceans and threaten aquatic life. And they leach toxins that seep into the water supply. Recycling is the only way to prevent this damage.

PETG USES

industrial uses

Medical Packaging

Because PETG retains its durability when exposed to heat,it has become a common way to package pharmaceuticals and medical devices. The thermoplastic can withstand radio-frequency sealing as well as sterilization processes such as ethylene oxide and gamma irradiation without losing its protective qualities or transparency.

Food Packaging

FDA-compliant, PETG is easy to thermoform and retains its transparency after heating – properties that make it a perfect choice for packaging in the food, beverage and cosmetics industries. In addition, the durability and light weight of PETG packaging reduces distribution costs associated with acrylic or glass packaging.

Machine Guards

Clear plastic machine guards play important roles in workplace safety and quality control. Workers can see what’s happening in a machine while being protected from moving parts and flying debris. More durable than acrylic and easier to form than polycarbonate, PETG machine guards are often used in food processing.

Everyday Users & Hobbyists

PETG has become more popular as more consumer-grade printers ship with heated print beds. Stronger and more flexible than PLA, PETG is more appropriate for everyday objects like smartphone cases. And unlike ABS, PETG does not require ventilation to remove noxious fumes making it safe for kids and pets to be around.

Wind-up boat

storage drawers

grape slicer

PETG benefits &
Characteristics

petg statistics

key features

odorless

environmentally safe

no heating bed required

advantages & disadvantages of petg

advantages of petg

PETG combines the best properties of PLA and ABS. You get strong parts that can support mechanical loads. PETG is naturally transparent which allows for unique effects. Its transparency also accepts a wide range of colors and blends. And PETG’s odorless emissions are non-toxic making it appropriate for both home and office use.

disadvantages of petg

Since PETG is more prone to oozing than PLA or ABS, you will have to experiment with retraction and bridging settings to get quality prints. Even then, you may need to do more post-processing to remove stringing and other blemishes. PETG readily absorbs water if not stored properly. This will make parts more brittle.

petg printing tips

Printers run hotter with PETG than with PLA: 230-260°C at the nozzle and 80-100°C on the bed.For best bed adhesion, use a PEI build plate and pause the part cooling fan for the first layers. Keep the print speed between 60mm/s and 100mm/s for consistent results. Avoid layer shifts by keeping the nozzle clean of PETG blobs.