Polyethylene (PE) bags are more flexible and resistant to cold temperatures, making them common for grocery bags, food packaging, and general storage. However, they tend to have lower clarity, reduced heat and chemical resistance, and may degrade faster under UV exposure, while not being as cost-effective as they seem.
Polypropylene (PP) bags are stronger, more rigid, and offer higher clarity, as well as better heat and chemical resistance, giving more benefits for their cost. They also provide a superior moisture barrier and can be easily colored, making them ideal for medical packaging, high-visibility food packaging, and industrial uses. The trade-off is lower flexibility and less cold resistance.
Choosing between PE and PP bags depends on the intended use. PE excels in flexible, impact-resistant and cold-storage packaging, while PP is preferred for strength, clarity, heat resistance and cost efficiency.
Polyethylene (PE) is one of the most resilient plastics around. As well as being incredibly durable, it’s resistant to tear. What’s more, it’s a remarkably flexible plastic. These features combine to produce a robust packaging solution that’s well-suited to bulky items.
Polyethylene bags and polyethylene liners are commonly used in industrial settings, with their tough nature perfect for storing heavy items like machinery parts and spares. However, their protective properties can also be put to use in wildly different settings.
Their soft, non-abrasive finish also makes polyethylene bags a good choice for delicate items that could scratch or scuff in transit.
There are several types of polyethylene, and the two you’ll come across most in packaging are low-density polyethylene (LDPE) and high-density polyethylene (HDPE). Note that PET (polyethylene terephthalate), used for drink bottles, is a polyester, not a type of polyethylene – despite having the term polyethylene in the name.
Low-density polyethylene (LDPE) is a flexible, fairly impermeable material. It boasts impressive moisture resistance, while withstanding impacts well. LDPE is chemical resistant, and can cope with extreme temperatures. It’s often used in protective packaging like bubble wrap and stretch film but is mainly used to produce plastic bags. High-density polyethylene (HDPE) is considerably stronger than LDPE, but there are some compromises when it comes to flexibility.
Looking for a more transparent packaging solution? With exceptional levels of clarity, polypropylene bags are the obvious choice. As they’re less opaque than their PE bag counterparts, this type of poly bag is an ideal food packaging option.
As well as transparency, polypropylene bags score high marks for durability and strength.
What’s more, the high tensile strength of polypropylene makes it very effective for storing goods or preparing them for transport.
Its stiffness helps bags hold their shape when filled and stacked, while also safeguarding contents against dents and scratches.
Low levels of permeability make polypropylene bags a fine fit for food products, locking out harmful contaminants and bacteria.
The transparency of this material is also useful for the customer. By providing a clear view of the products inside, consumers don’t have to take chances when handing over their hard-earned cash.
Despite the many benefits of polypropylene bags, they remain an affordable option and handle heat, moisture and outdoor exposure well, although they become brittle in freezing conditions.
If you’re looking for a lightweight and durable poly bag, polypropylene ones are an easy choice. Ideal for use in the food processing and manufacturing sectors, polypropylene bags should be fully compliant with the latest regulations and industry recommendations if you’re sourcing them from a legitimate supplier.
What’s more, their exceptional tensile strength means they can carry heavy loads without stretching, making them a versatile packaging solution.
A high melting point also brings peace of mind and broadens applications, while you can rest assured that contents are safeguarded from outside vapors, moisture, and harmful contaminants. Need more convincing? In most cases, polypropylene bags are also cheaper than polyethylene ones.
Feature | Polyethylene (PE) | Polypropylene (PP) |
Transparency | Semi-transparent | High clarity |
Flexibility | Highly flexible, soft finish | Stiffer, holds its shape |
Strength | Better impact and tear resistance | Higher tensile strength and rigidity |
Density | 0.91 to 0.94 g/cm³ | 0.90 to 0.91 g/cm³ (lighter) |
Melting point | 115 to 135°C (239 to 275°F) | 130 to 171°C (266 to 340°F) |
Cold performance | Stays flexible below freezing | Becomes brittle near and below freezing |
UV resistance | Degrades faster unless UV-stabilized | Better UV stability, especially with stabilizers |
Chemical resistance | Good | Excellent |
Recycling code | #2 (HDPE), #4 (LDPE) | #5 (PP) |
Cost | Slightly higher | Lower |
Common formats | Film bags, liners, container liners | Clear film bags, woven sacks, FIBC bulk bags |
Best for | Cold storage, heavy or sharp items, liners | Food packaging, heat exposure, visibility, bulk transport |
While polyethylene bags tend to be more expensive than polypropylene ones, they come with many attractive benefits. As well as being tear-resistant and exceptionally durable, the flexible nature of polyethylene gives it a surprisingly soft finish. This means that, when used as packaging, polyethylene bags will cause no damage to the items within.
Polyethylene bags are resistant to cold temperatures, making them a good option for storing items in frigid conditions like poorly heated warehouses. Dust and dirt are also kept at bay, while a relatively low static charge means you have one less health and safety concern to worry about.
If you plan on using poly bags in more challenging environments, you’ll need to consider the heat and chemical resistance properties of each type. Will your packaging be exposed to chemicals and corrosive agents? While polyethylene bags are generally more durable than polypropylene ones, the latter outperforms the other when it comes to chemical resistance.
PP bags are also far more resistant to extreme heat than PE ones. PP bags can withstand high temperatures of up to 340 degrees Fahrenheit, while PE bags can only handle extreme highs of around 240 degrees Fahrenheit. However, PE bags come out on top as far as extreme cold is concerned. They can withstand temperatures as low as -110 degrees Fahrenheit. By contrast, PP bags start to lose their structural integrity once they pass the point of freezing.
With more businesses looking to make sustainable choices, recyclability matters. Both PE and PP are thermoplastics, so they can be melted down and reformed into new products. You can identify them by their resin codes: #2 for HDPE, #4 for LDPE and #5 for PP. In practice, polyethylene is recycled more widely than polypropylene, as more collection and reprocessing systems accept it. To keep either material recyclable, avoid mixing PE and PP in the same bag where possible, and check what your local or regional recycling streams accept.
FIBC bags rely on both PP/PE bag materials, each doing a different job. The bag body, lifting loops and spouts are woven from polypropylene tapes, giving the bag the tensile strength to carry heavy bulk loads. The fabric can also be coated to make it more sift-proof and moisture-resistant. Polyethylene comes in as the liner. Placed inside the bag, a PE liner adds a full moisture barrier and stops fine powders escaping through the weave. LDPE liners flex to fit irregular shapes and suit food-grade and moisture-sensitive goods, while HDPE liners resist punctures and aggressive chemicals. Liners come as lay-flat tubes or form-fit designs that match the bag’s spouts, and conductive or anti-static versions are available for hazardous environments.
Looking for hard-wearing packaging solutions for logistical operations?
Whether you’re active in the pet food manufacturing market or deal with chemicals and fertilizers, poly bags are a cost-effective and reliable choice.
At Codefine, we’ve been helping global businesses achieve logistical success for decades. Along with a first-rate range of poly bags, you’ll find premium packaging solutions used across just about every industry sector. Not sure what type of packaging you need? Take a look at our complete product range online or get in touch to see how we can help you.
Polypropylene bags usually cost less than polyethylene bags of the same size. PP resin is generally cheaper, and because it is slightly lighter and stronger, you need less material for the same performance. Polyethylene carries a small premium for its impact resistance and cold performance, which matters most in frozen and heavy-duty applications.
Both materials are covered by the same core food-contact rules, such as Regulation (EU) No 10/2011 in Europe and FDA 21 CFR 177.1520 in the US. The difference lies in the application. Some industries require specific material declarations, migration testing or UN certification for hazardous goods. Always ask your supplier for a declaration of compliance for your specific use.
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