While polyethylene (PE) and polyethylene terephthalate (PET) might sound similar, the two materials are completely separate polymers with distinct properties and applications. If you have to choose between using PE vs. PET for your product, you should know the characteristics of these two plastics, including their chemical structure, appearance, temperature resistance, cost, and environmental impact.
What Are the Differences Between PE and PET?
PE and PET are plastics that you can find almost anywhere, from grocery stores to industrial plants. These two polymers, which are molecular chains of molecules, or monomers, contain different molecules and have distinctive properties.
Chemical Structure
The polymer PE is a repeating chain of ethylene molecules. PE’s chemical structure consists of carbon atoms and hydrogen atoms, and PE has the chemical formula (C2H4)n.
PET is a polymer made from ethylene glycol and terephthalic acid. The chemical formula for PET is (C10H8O4)n, representing a repeating chain of monomers with carbon, hydrogen, and oxygen atoms.
Mechanical Properties
PE has mechanical properties that vary depending on its different forms, such as high-density polyethylene (HDPE) and low-density polyethylene (LDPE). HDPE is a durable, rigid material, while LDPE is soft and stretches more easily.
PET is a sturdy, lightweight plastic that has a high strength-to-weight ratio, which is one of the reasons why it’s such a versatile and affordable material.
Clarity
PET is one of the most transparent plastics, making it suitable for water bottles and other types of clear packaging. PE ranges from opaque to transparent, depending on the density of the polymer.
Barrier Property
PET and PE are both good moisture barriers. PET has lower gas permeability compared to PE, so it’s better at keeping oxygen and carbon dioxide out, helping extend the shelf life of products with PET packaging.
Recyclability
PE and PET are both easy to recycle, but PET retains its original properties better than PE, even when it goes through recycling many times.
Applications
PET can be food packaging, polyester fibers, bottles, and microwavable containers. PE applications depend on the density of the plastic, but common uses are storage containers, plastic bags, drink bottles, and household items.
Cost
PET and PE are both inexpensive plastics with similar prices, but PE plastics can cost more. In 2022, HDPE cost $1,106 per metric ton, while PET cost about $950 per metric ton.
Comparing the Advantages of PE vs. PET
Compare the unique advantages of PE and PET to help you decide which plastic is best for your goals and applications.
Advantages of PE
PE provides these benefits:
- High availability
- Low cost
- Resistance to wear and tear
- Good electrical insulation
- Different thicknesses and clarities
- Easy recycling
Advantages of PET
Advantages of PET include:
- Lightweight
- Shatterproof
- Suitable for food containers
- High strength
- Moisture resistant
- Easily recyclable
Can PE and PET Be Recycled?
PE and PET are both easily recyclable plastics that many companies use and reclaim to create new plastic products.
Recycled PET is versatile, becoming new products like clothing, drink bottles, or car parts, and using the recycled material is better for the environment than producing new PET. While recycled PET might look different because of impurities in the plastic, mixing it with new PET can improve its appearance.
Common Uses of PE and PET
PE and PET have many shared applications, but in some cases, one plastic is a better choice than the other.
PE Applications
Here are some of the frequent uses of PE:
- Plastic bags
- Food containers
- Plastic trays
- Bottles
- Water pipes
- Kitchenware
- Wire insulation
PET Applications
The following are applications of PET:
- Water and soft drink bottles
- Microwavable containers
- Car parts
- Food packaging
- Polyester fabrics
Sustainability and Environmental Impact of PET and PE
Plastics have a bad reputation when it comes to their impact on the ecosystem. Certain manufacturing processes for PE and PET can hurt the environment, and most of the material goes into landfills or oceans instead of recycling facilities. However, PE and PET have high sustainability potential with the right recycling practices.
Recycling and Reusability
One of the reasons PE and PET are so widespread is that they’re both very easy to recycle, and companies can use the recycled material to produce more plastic products. Since the primary use of PET is for plastic drink bottles, sorting and recycling the plastic usually takes less work than for other plastics.
While most food products don’t use recycled plastic because of the risk of contamination, PE and PET are highly reusable for other applications, including clothing and fibers.
Biodegradability
PE and PET are resistant to breaking down in the environment, emphasizing the importance of continuing recycling efforts for these plastics. A study found that PE only partially degrades even when sitting in moist soil for 12 to 32 years.
Landfill Impact
Since PE and PET lack efficient biodegradability, and most companies and consumers don’t recycle the plastics, landfills are overflowing with them. Every year, tons of non-degradable plastics find their way into the environment, including landfills and oceans, causing significant harm to the ecosystem.
Government Regulations and Restrictions on Using PE and PET
The Food and Drug Administration (FDA) provides a list of approved plastics for use in food packaging, which includes PE and PET. The FDA approved recycled PET for food contact, but only some recycled PE meets the standards for containing food products. For example, both HDPE and LDPE (high-density polyethylene and low-density polyethylene, respectively) are sometimes used in food containment, but studies for both have shown that there may be risks attached.
How Can You Determine Whether To Use PE or PET For Your Application?
Both PE and PET are inexpensive, durable plastics with a wide range of uses, but the best choice depends on your application and business needs.
PET is lightweight, can take on many appearances, and is highly resistant to potentially harmful chemicals. PE, however, holds up slightly better against impacts than PET and has superior temperature protection.
Contact TDI Packsys for Reliable Packaging Solutions
When deciding between PE vs. PET for your product, it helps to weigh the advantages of both common plastic materials based on their properties and environmental impact. If you have questions about the food packaging processes, call 877-834-6750 to consult with our experts today.
