Polyethylene and polypropylene are two of the most commonly used plastics in the world. Both of them being polymers, they share a lot of similarities, and it can be hard to find the differences between the two. But they do have a lot of characteristics that are unique to each other, and knowing them will make it easier for you to choose which one to use, depending on your needs.
Polyethylene is known for its lightweightness, excellent durability and affordability. It is commonly used for manufacturing stock poly bags, zip lock bags and bottles. The most commonly used polyethylene plastics are high density polyethylene (HDPE), low density polyethylene (LDPE), and polyethylene terephthalate (PET).
HDPE has high tensile strength and strength-to-density ratio, can withstand temperatures of up to 120 °C, and is resistant to a lot of solvents. It is also opaque, which is great for storing items that are sensitive to light exposure. Examples of HDPE items include milk jugs and water drums.
While not as tough as HDPE, LDPE is more flexible physically. It has lower tensile strength but has higher resilience, is not reactive to room temperatures, and is highly resistant to most acids, alcohols and bases. Examples: disposable gloves, packaging foam.
PET is commonly used as bottles for carbonated drinks, but can also be used as fibers for garments. It can withstand very low temperatures, has a great barrier against gas and moisture, can be made to be rigid while still being lightweight, and is fully recyclable.
Polypropylene has a lot of similarities with polyethylene in that it can be designed to be durable and lightweight. Aside from these, polypropylene has excellent mechanical properties and high resistance to fatigue, impact, heat and freezing. It is highly resistant to corrosion and chemical leaching, making it ideal for storing solvents, bases and acids.
Polypropylene is the second most commonly used plastic after polyethylene. It is used in many applications similar to polyethylene such as bottles and gloves. Unlike the latter, though, it has a crystal-clear transparency. It is also pure and non-stretching, unlike polyethylene.
Which should you use?
There are a lot of similarities between polyethylene and polypropylene, but they also have characteristics that are unique to each other, which can be maximised depending on how they are made and the applications they are used for.
Tapes (e-tapes, double adhesives etc.)
Polyethylene tapes have excellent resistance against tear and abrasion. They can adhere really well on many surfaces, and they have great low temperature bond. They are also highly conformable, which makes them usable in a wide range of sealing applications.
Polypropylene tapes can have the same tensile strength and damage resistance as polyethylene tapes, the only difference being that they are more affordable than the latter. The downside, however, is that they can be noisy to use.
Both of these polymers are commonly made into stock poly bags. Polyethylene bags are semi-transparent, which is great for limiting light entry when storing items that are sensitive to light. They have low static charge, ideal for electronic components, and has higher resistance to rips and tears compared to polypropylene.
Polypropylene bags have crystal clear transparency, which is great if you want to store items in way that all details are shown. Polypropylene can also prevent evaporation and exposure of items to bacteria, so you can use them for storing, for example, medical equipment.
Polyethylene gloves are cheaper than their polypropylene counterparts. They also typically come powder and latex-free, which is why they are highly used in applications that involve food. They don’t trigger allergic reactions, so they are safe to use.
Although more expensive than polyethylene gloves, most polypropylene gloves are durable, which means they can be reused a number of times before they’re needed to be discarded. Polypropylene gloves can have moisture-wicking properties, and they can be worn as liners for warmth.
Plastic products by Hunter Industrial Supplies
For all your plastic product supply needs, check out the Hunter Industrial Supplies catalogue! We provide adhesives, e-tapes, gloves, stock poly bags, zip lock bags, and other packaging and storage products made of high quality polyethylene and polypropylene. Visit the Hunter Industrial Supplies website to learn more about our products. Don’t forget to read our other blogs for more tips on item packaging, strapping and storage.