What is PET Plastic | The Ultimate Guide

What is PET Plastic?

Polyethylene terephthalate, better known as PET Plastic (also sometimes as PETE ), is the most used thermoplastics globally in various textiles, films, electronics, packaging, automobiles, etc. The biggest utilizer of PET is the textile industry, in which thermoplastic is mostly known by the name Polyester. It has a fantastic set of different properties, like chemical, mechanical, thermal resistance, and dimensional stability. Making it very attractive for manufacturers

PET structure is made by combining ethylene glycol and terephthalic acid through a process called condensation. This results in repeating units of ethylene terephthalate, which form the polymer. It is semi-crystalline in nature and colorless. Some of the important properties include water resistance and toughness (the strength-to-weight ratio is impressive). The material is virtually shatterproof, which improves its applicability by many nautches.

PET plastic is also highly recyclable (which we’ll discuss later in the article ) and has the number “1” as its recycling symbol.

According to many worldwide reports, PET, with an annual production of 56 metric tons, is the most used thermoplastic in the world. The textile industry consumes approximately 60% of that, and other major consumers include the packaging and bottling industry with 30%.

PET Copolymers 

PET or PETE is originally a homopolymer but can be modified to produce copolymers ( polyethylene terephthalate glycol-modified ) depending on the application.

The commonly used modifiers to produce PETG are cyclohexane dimethanol (CHDM) and isophthalic acid, respectively.

These polymers predominantly react with crystallization, thereby changing or lowering the polymer’s temperature.

PET Characteristics 

PET or polyethylene terephthalate has many consequential properties. Let’s talk about them.

Chemical Resistance: PET has a significant amount of resistance toward the water, food, and natural cause like bacteria, fungi, etc. That makes it compatible with food packaging applications.

Transmittance: It is naturally transparent. However, it doesn’t look exciting compared to other highly transparent polymers like Polycarbonate and Acrylic. If high transparency is required, these polymers should be used instead of PET.

Shatterproof: PET plastic is solid and strong. PET density is 1.38 g/cm³ and It is virtually shatterproof and thus used as an alternative to glass.

Polyethylene terephthalate is originally a thermoplastic, and it is decided by the way it reacts to heat. However, there are many variants of polyesters that are considered thermosets.

The major difference between thermoplastics and thermosets can be attributed to how they react to heat. Thermoplastic melts at its melting point ( 260°C for polyester ).

The major benefit of any thermoplastics when it needs to be processed in injection molding is that when it melts, the liquid form can be cooled and reheated without large degradation.

On the contrary, thermosets can only be burned once as the first heating changes their chemical nature that cannot be reversed.

Once their chemical nature is changed, any additional heating will burn the polymer—That’s one of the main reasons for thermosets being poor candidates for recycling.

Faacinating Read – What is PETG Material? | The Definitive Guide

How is PET Made?

For PET Plastic, like other thermoplastics, the making process starts with hydrocarbon fuels filtration into smaller parts called “fractions.”

A certain amount of extracted fractions can be combined with catalysts to produce plastics—the process is called polymerization or polycondensation. The only major difference for PET is the combination of hydrocarbon ethylene glycol and terephthalic acid.

Interesting Read – What is Expanded Polystyrene (EPS) Foam?

Processing Conditions for PET Plastic 

PET is perfectly compatible with injection molding, Blow Molding, Extrusion Molding, and 3D Printing processes. The general use for PET plastic is extruding produce films and sheets.

It is advisable to dry polyethylene terephthalate for up to 2-3 hours before processing.

 Applications 

• Because PET has phenomenal water and barrier-resistive properties, it is often used to manufacture plastic bottles for mineral water, alcohol, and carbonated drinks.
• Non-Oriented PET is often thermoformed to produce packaging trays, plastic cups, and blisters.
• Its Rigidness and fabulous mechanical strength make it a prime choice for manufacturing tapes.
• A range of physical properties coupled with chemical inoperativeness makes it compatible with food packaging applications.
• Polyester is one of the most polymers in the textile industry.
• The packaging industry is also very dependent on PET for microwave containers, rigid jars, transparent films, sheets, etc.

 Advantages and Disadvantages of PET 

Advantages

• PET possesses a high strength-to-weight ratio (a rare quality found). Thus, easy and inexpensive to transport.
• It is available in abundance and is inexpensive compared to other thermoplastics.
• It is moisture resistant.
• It shows fantastic electrical insulating properties.
• PET is smack and fracture-proof, making it a good alternative to glass in many applications.
• It exhibits high resistance to organic matter and water, which can become advantageous or a nuisance depending on the application.
• PET is approved to be safe with food and beverages. Agencies like FDA, Health Canada, and EFSA have given it a free flag.
• Polyethylene terephthalate can be recycled. Recycling includes a series of washing processes; after that, it can be reused.
• It is transparent to microwave radiation.
• Compared to its closest competitor, Polybutylene terephthalate (PBT), PET shows higher heat distortion temperature (HDT).

Disadvantages

Polyethylene terephthalate comes with great qualities, and the positives obviously outshine the negatives, but we should still look at them.

• PET is not biodegradable
• PET is somewhat vulnerable to oxidation (But nothing is rock solid proof about this).

Recycling of PET Plastic and its Effects on the Environment 

Polyethylene Terephthalate is a 100% recyclable material and, to its credit, is the most recycled thermoplastic in the world.

The recycling code “1” says it all.

The low diffusion coefficient is the prime reason for PET is the best when used with recycled material.

The used PET products are collected and stored using a special process and go through a kind of washing or chemical process to break them down into small pieces called PET flakes. Manufacturers use these recycled PET flakes for strapping, films, and sheets, Food and beverages containers, carpets, flee bags, etc.

Interesting Read – What is Polypropylene Material? | The Ultimate Guide

FAQs

Below are the frequently asked questions on PET polymer. Let’s dig deep to know more.

Which Plastic material is better? PET or Polycarbonate?

Both PC and PET have their pros and cons. Polycarbonate has better catch resistance and is easier to wash, but PET resin is cheaper than polycarbonate; however, that doesn’t necessarily translate into good profits as equipment to process PET bottles are more expensive.

Which Plastic material is better? PET or Polypropylene?

Both plastic materials are heavily utilized in the plastics processing industry, and they have advantages and disadvantages. Talking about PET, its products have slightly better impact resistance than products made from polypropylene. In addition, PET containers are often regarded as best for maintaining the taste and aroma of food, thanks to their great oxygen barrier properties. On the other hand, PP containers fare better in moisture, alcohol, and chemical resistance.

Why is PET easier to recycle than PP?

PET is easier to recycle than PP because its polymer chain breaks down at a relatively low temperature. As a result, there is minimal degradation of the polymer chain during the recycling process. On the other hand, the degradation of PP during the recycling process is more fierce, resulting in more difficulties in recycling.

At what temperature do plastic bottles melt?

PET bottles usually melt at a temperature of 255 degrees Celsius (491 degrees Fahrenheit).

How many times PET bottles can be recycled?

New scientific studies conducted in the US show that PET and HDPE bottles have a significant market share in the American bottling industry and can be recycled at least 10 times.

Final Thoughts 

Finally, I would like to say that PET plastic, along with its few variations, is useful for any plastic manufacturer. Adding them to your business would help you bring down the costs substantially and shoot your profits sky-high.

Thanks for reading the article. Kindly comment on your thoughts and reviews in the comment box.

Have a fantastic day.