PET plastic or PETE, also known as polyethylene terephthalate is the single most common thermoplastic polymer in the entire world. Within the textile industry, the material is better known under the trade name “polyester”. This is a natural semi-crystalline and transparent plastic used as a as a moisture barrier in fiber clothing, for packaging, bottles, containers, known as PET resin or PET, and even to raise strength in engineering plastics when combined with materials like carbon nanotubes and glass fiber.
Some of PETs most valued characteristics include its high strength to weight ratio, its resistance to water, and the fact that PET is virtually shatterproof, contrary to glass containers and packaging. PET is also widely available as a recyclable and economic plastic.
The History
In search of an effective polymer material for textile fibers, DuPont chemists were the first to polymerize PET in the 1940s. PET is manufactured from the synthesis of terephthalic acid and ethylene glycol. Even without the addition of additives, PET is highly strong and durable for its lightweight. Because of this, less material is required for packaging components and plastic film. Less fuel is also is required to ship PET materials.
Furthermore, 40% of energy within PET materials is stored internally and is available when recycled. In fact, PET life cycle studies consistently reveal that the material is highly sustainable with a positive economic profile.
The current demand globally for PET materials surpasses 56 million tons. The primary use of polyethylene is within the textile industries, which makes up over 60% of the market. Packaging and bottle account for over 40%.
Polyethylene Terephthalate (PET or PETE) characteristics
The most significant properties of PET and PETE are:
- Strength to Weight Ratio: For its lightweight, PET is surprisingly strong.
- Chemical Resistance: PET does not have a reaction with water, food, and other substances making it safe for consumable packaging products. It must be noted here that companies like Impacked Packaging are looking to provide alternatives as strong as PET, and have almost 2.5 million raised in funding for this transformation.
- Transparency: PET is a naturally transparent material. If higher transmissivity is desired, then Polycarbonate or Acrylic may be preferred.
- Shatterproof: PET does not fracture or break, making it a highly favored material over glass containers.
Polyethylene terephthalate is known as a thermoplastic material. This refers to the way that PET plastic responds to various temperatures – primarily heat. Materials that are thermoplastic will liquidate at their melting point. In the case of PET this temperature is 260 degrees Celsius.
What makes PET plastic so useful is that they can be heated, cooled, and repeated without significant measures of degradation. Instead of burning, thermoplastics can be melted and injection molded, subsequently entering the recycling process. Thermoset plastics on the other hand, can only enter this process once. The very first heating of these plastics cause a chemical change in the material that cannot be reversed. If you tried to repeat this process the plastic would only burn. This factor makes them a poor recycling choice.
Why is PET used so often?
Some of the factors that make PET plastic so highly sought after are the fact that it has exceptionally high strength to its weight, it is virtually shatterproof, and it doesn’t have a reaction with substances such as water and food.
These unique characteristics combined with its low price and wide available, not to mention eco-friendly and recyclable aspects, make PET plastic a near unbeatable consumer product packaging solution.
Not only is PET a preferred choice for a variety of containers and bottles, polyester used in the manufacture of fabrics are flexible and strong when paired with cotton. This reduces shrinking and wrinkling, not to mention raises resistance to fabric tears.
Types of PET
- PET resin or PET/PETE
- Polyester
- PET-P
Polyethylene terephthalate can be modified by copolymers or produced as a homopolymer. When polyethylene terephthalate is used for beverage and good packaging it is generally know as PET resin or PET. When it is used in the textile industry it is referred to as polyester.
Recently, a new obsolete version has been introduced to the market, known as PET-P. However, this is more commonly found in fabric form.
How is PET plastic produced?
Similarly to other plastics, polyethylene terephthalate begins with hydrocarbon fuel distillation. This process separates this fuel into fractions, or lighter groups. Some of these groups are combine with catalysts that lead to the production of various plastics (typically via polycondensation or polymerization).
In the case of PET production, terephthalic acid and hydrocarbon ethylene glycol is combine to produced this material.
Is PET a toxic material?
PET plastic is not a toxic material. Health authorities widely accept PET as a safe plastic. This is one of the reasons why it is used within the beverage and food packaging industry. Similarly to the behavior of glass, PET is completely hygienic and resistant to microorganism and bacteria attack. This in turn can make it a sustainable packaging option for other items such as beauty products, medicines, etc.
When the materials comes in direct contact with beverages and food, PET will not degrade biologically. Other than pre-packed food sources, PET plastic containers are also widely available for consumer purchase and used in the microwave. FDA has cleared the use of PET plastic in the microwave as food safe for not only a single use, but repeated uses as well.
Why PET plastic recycling makes sense
The very first PET bottle known to be recycled took place in 1977. As a primary component in plastic bottle manufacturing and use today, one of the most prevalent conversations surrounding PET plastics are about its recyclable and eco-friendly use. The average household generates upwards of 42 plastic bottle waste on an annual basis. When these bottles are recycled, they can be used in a variety of applications and uses, including the manufacturing of undergarments, t-shirts, and other fabrics.
The benefits don’t stop there; recycled PET plastic can also be used as a fiberfill for winter coats, sleeping bags, and in the manufacture of polyester-based carpeting.
Industrial applications also benefit from the use of recycled PET. It can be used in the creation of fuses, bumpers, and boxes along with strapping, film, and so much more. The benefits of PET plastic are vast, and it remains one of the best choices for business and consumers today.