What is POLY BAG

A poly bag is a common shipping and packaging resource made of polymer material that is exceptionally durable, pliable, and customizable to fit any application. Made of polyethylene or polystyrene materials, poly bags are a precisely engineered and designed compact method for protecting and securing products, parts, and merchandise.

The three basic types of poly plastic bags are:



Low-density polyethylene

  • LDPE bags are characterized by flexibility, tensile strength, and waterproof abilities. They are commonly used for food packaging and cleanroom applications due to their clarity, enhanced flexibility, and supple feel.



Linear low-density polyethylene

  • LLDPE is characterized by incredible strength, durability, and puncture resistance. You can use it to accommodate sensitive products, especially since they offer higher tensile strength and durability than LDPE.



High-density polyethylene

  • HDPE features densely packed molecules delivering a rigid, robust, and durable bag structure. For that reason, HDPE is used for storing large volumes of weight. Additionally, HDPE Bags are opaque, water-, and heat-resistant, meaning that they’re safe for transporting food and sensitive cleanroom applications.

A regular poly bag is any bag made of plastic, and it’s commonly used for packaging and shipping. Poly bags are lightweight, multipurpose, and made from recyclable materials, which limits their environmental impact.

While poly bags are convenient for various industrial and domestic uses, certain customization options are available, as well. You can have a poly bag in different colors and printed logos, which you can use for commercial purposes. Moreover, poly bags are a popular choice for food packaging, but, in that case, they must comply with FDA regulations. Another popular form of poly bags refers to gusseted poly bags, suitable for storing bulky goods and greater quantities than classic, flat bags.

LDPE vs. HDPE Bags

Although HDPE and LDPE bags share some similarities, certain characteristics make a huge difference between them. The main reason for that is the branching of polymer chains, which, in the case of HDPE, have a more crystalline structure.

Physical Differences Between LDPE and HDPE Bags

LDPE is, essentially, softer and more flexible than HDPE. It features a lower melting point of 239 °F and is more transparent than its high-density counterpart. For that reason, it’s more prone to cracking when under stress.

On the other hand, HDPE provides better chemical resistance and has a higher melting point – 275 °F. Therefore, it can withstand higher temperatures than LDPE. Overall, HDPE is more rigid and durable than LDPE, and its crystalline structure offers greater strength and opacity.

Recycling Differences

  • LDPE and HDPE are both recyclable, but they cannot be recycled together. While LDPE carries recycling number 4, HDPE falls under recycling number 2. Another difference lies in the recycling difficulty – LDPE bags are more difficult to recycle due to their soft structure (they frequently get caught in the machinery), and HDPE can run through recycling equipment more easily.
  • Despite their differences, LDPE and HDPE still have something in common. Aside from being made from the same polymerized ethylene materials, they share the following given features:

Industries Using Both LDPE and HDPE

Since LDPE and HDPE can be used for various applications, some industries can benefit from both. For example:

Medical devices

Industries involving medical device manufacturing and transportation often use HDPE bags for medical waste containers or plastic lab bottles. On the other hand, low-cost & durable LDPE bags are used for various cleanroom applications.


Both HDPE and LDPE play a vital role in the packaging industry. While HDPE is widely used in plastic packaging, bottles, and household and industrial chemical containers, LDPE is a go-to choice when heat sealing is necessary.

Life sciences

Due to their virgin and surfactant-free materials, LDPE and HDPE bags prevent contamination of life sciences products.