Polyethylene terephthalate, or PET, is a type of plastic resin as well as a form of polyester. It can be fully recycled, in which case it becomes recycled polyethylene terephthalate, or rPET. Essentially, the material is a polymer, which is made by combining purified terephthalic acid and modified ethylene glycol, both monomers. PET was originally discovered in 1941 in the United Kingdom, where it was also patented.
If you grab a container or bottle, you may notice a #1 code on the bottom of it. That is to say it is made out of PET. It is very common as a packaging material, including things like peanut butter, beverages, produce, bakery goods, salad, frozen foods, cosmetics, dressings, and household cleaners. PET itself is incredibly popular because it is transparent, thermo-stable and incredibly durable. Additionally, it is lightweight, affordable, shatter resistant, resealable and, most important of all, recyclable. This is where rPET comes in.
rPET is created by recycling plastics that were previously used as packaging materials. These include plastic bottles, for instance. Once collected, it is sorted and cleaned, after which it is transformed into rPET, which can then be used for new packaging. This is federally approved and effectively means that you can give each bottle a new lease of life.
Some rPET Factoids
By recycling PET bottles and turning them into rPET, you conserve a great amount of landfill space. In fact:
- 4,800 16oz bottles equals one cubic yard.
- 4,050 20oz bottles equals one cubic yard.
- 3,240 1 liter bottles equals one cubic yard.
- 2,430 2 liter bottles equals one cubic yard.
- 1,350 3 liter bottles equals one cubic yard.
- One ton of PET equals 7.4 cubic yards.
There are a number of other interesting things to know about recycling PET:
- The Environmental Protection Agency says that 12,000 BTUs (approximately) are saved by recycling just one pound of PET.
- In 2005, each household generated an average of 42 pounds of PET just from plastic bottles.
- 62% of all PET bottles that can be recycled are custom bottles, which means they were not used for carbonated soft drinks.
How Is rPET Used?
rPET can be used in a huge variety of ways. These include:
- Tee shirt fabric
- Polyester carpet fibers
- Athletic shoes
- Long underwear
- Fiberfill for winter coats, sleeping bags and sweaters
- Sheet and film
- Industrial strapping
- New PET containers
- Automotive parts
This shows the breath and width of possibilities offered by PET. Perhaps most interesting is the fact that 100% of all PET can actually be made from rPET. It is so versatile, as well, that it can be used for food and non-food products alike. It is, in fact, so safe, that it can be recycled over and over again, reusing each element to create new ones each time.
Both in this country and in Canada, there is a huge demand for rPET. The demand is, in fact, so high that insufficient bottles are being collected to meet it. This is because rPET can be used in so many different new products. As a result of this shortage, some new PET must also be created. Consumers now actively look for companies that are committed to sustainability, recycling and the overall green agenda. As such, manufacturers improve their standing by using rPET as much as possible.
How rPET Is Collected, Sorted and Processed
Usually, PET is collected through programs such as curbside recycling. This involves both what is known as a single-stream approach and a dual-stream approach. However, because there is such a shortage of PET, other recycling programs are also being set up in different communities across the country. For instance, there are recycling banks and recycling drives, and various community education programs exist in order to further promote recycling.
At a recycling center or material recovery center, PET is sorted from the various other recyclable materials. It is then baled, after which it is sent to specific PET recycling facilities. These are federally authorized to process the material. It is very important that PET is stored and handled properly, however, so that it is not contaminated and so that the workplaces are 100% safe. This is why various federal regulations are now in place.
Once the bales of PET arrive at a recycling facility, they are first staged. Then, they are placed onto a conveyor, which takes them through a bale braker. This brakes the bales, and the bottles then become singulated. It is vital that all bottles are properly washed and that their labels are removed. Steam is used, as well as various chemicals. To do this, the bottles are placed into a hot air trommel, which is known as the 'pre-wash stage'. If any PVC bottles have accidentally made their way into the bale, they will turn slightly brown during this process. This then enables them to be removed.
Most licensed PET facilities use near infrared (NIR) equipment to sort through the bottles and to remove contaminants. They usually also use metal detectors to further sort the materials. Finally, they will go through a sorting belt, where employees remove any final materials, leaving just the PET in place.
After sorting, the material is then ground, which creates what is known as 'flakes'. These flakes have to be completely pure in order to make sure they can be turned into rPET. If they are contaminated, functionality, strength and, ultimately, value will be significantly reduced. This is why various separation techniques are usually used along the way, including air classification and washing.
Once all the steps have been completed and the facility is sure that no contaminants remain, the material is rinsed one more time. After it is dried, it becomes a new manufacturing material by being reintroduced. Actually, manufacturing new items out of the rPET is generally done at other facilities.
Sometimes, however, the material has to be purified even more. This can be done though melt filtering. This means that any contaminants that still remain that don't melt will be taken out of the rPET. The melted material passes through screens, eventually forming pellets when drying again. This is known as pelletized plastic, which is more efficient for transportation and re-manufacturing, as well as providing more uniform sizing.