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08 May 2023

Differences between polyethylene and polypropylene packaging

The characteristics of polyethylene and polypropylene in a nutshell

Polyethylene and polypropylene packaging can both be used to package food, pharmaceutical and industrial products. However, there are some important differeces between the two materials, starting with their chemical structure, which influences their physical and mechanical properties.

In this article we will look at the main differences between polyethylene and polypropylene packaging, the specific characteristics of these two polymers and their different applications.

Polyethylene and polypropylene: thermoplastics

Polyethylene and polypropylene are both versatile thermoplastics that are widely used in various industries and for the manufacture of everyday consumer products. Thermoplastics have the ability to be melted and moulded repeatedly at high temperatures without undergoing chemical changes or loss of physical properties.

This process is reversible and does not result in any loss of material properties or quality, unlike thermosets that decompose irreversibly when heated.

Thanks to these special characteristics, polyethylene and polypropylene packaging has many advantages, including:

  • the possibility of being easily moulded and adapted to the shape of the products the y are to contain;
  • greater resistance to mechanical stress than thermosettig materials;
  • more efficient and sustainable recylcing, as they can be melted down and reused for the production of new products, thus reducing environmental impact.

Thanks to these properties, polyethylene and polypropylene have become widely used materials for the production of packaging and everyday goods, which has contributed to their global spread.

The difference between polyethylene and polypropylene: characteristics and properties

Although they are both thermoplastics, polyethylene and polypropylene differ substantially in terms of chemical composition:

  • Polyethylene (PE) consists of repeating units of ethylene, is insoluble in water and has a low chemical reactivity. It is a flexible and transparent plastic materia, commonly used to produce food bags, containers and stretch film. It is easy to process, has good resistance to chemicals and low permeability to moisture, air and gases. Depending on the distribution of molecular weights and the degree of branching, it is possible to obtain different types of polyethylene with different properties and uses. Among these, we can distinguish high-density polyethylene (HDPE), low-density polyethylene (LDPE) and expanded polyethylene. Based on these characteristics, the most suitable types of polyethylene can be selected for the specific needs of each application, thus ensuring maximum efficiency and performance of the end product.
  • Polypropylene (PP), on the other hand, consists of repeating uits of propylene, is also insoluble in water and has a higher chemical reactivity than polyethylene. It is a more rigid and opaque plastic material, commonly used to produce bottles, food containers and chemical packaging. Polypropylene is less susceptible to photochemical and thermal degradation than polyethylene, in fact, it can remain unchanged up to 100°C. but is more vulnerable to chemical decomposition by organic solvents and acids.

In general, both polyethylene and polypropylene are resistant to most chemicals, including detergents, oils and greases, but differ in their chemical and physical properties.

What are the different applications of polyethylene and polypropylene packaging?

Due to their excellent properties, these thermoplastic resins have a variety of applications, especially for packaging. Polyethylene has a wide range of applications for both industrial and food packaging. For example, polyethylene reels are suitable for packaging, protecting and wrapping industrial products, such as treated aluminium profiles, or for packaging using automatic packaging machines. While polyethylene suitable for food contact is useful for making food bags, spools and sheets for stroing and transporting fresh and preserved food, especially during processing, where protection is needed between the food and the basket or tubs in which it is transported.

Due to its higher mechanical strenghtm polypropylene is used intead of the production of rigid containers, however, transparent polypropylene packaging can also be obtained from it in the form of sheets, bags and reels. Other uses include the production of automotive components due to its ability to withstand high temperatures and chemicals.

Plastisac is a company specialising in the production of high-quality packaging in polyethylene and post-consumer recycled polyethylene, an innovative and sustainable material. Thanks to its experience and expertise in the sector, Plastisac is able to offer customised solutions for every packaging need, guaranteeing the highest quality and environmental sustainability possible.

In particular, the post-consumer recycled polyethylene products (aimed at various sectors, with the exception of the biomedical and food sectors), allow for the re-use of the plastic already used, contributing to the reduction of the environmental impact and the preservation of natural resources. Thanks to advanced technology and rigoroud quality control procedures, Plastisac guarantees the maximum reliability and safate of its products, providing eco-sustainable solutions to customers and consumers aware of the importance of a responsible approach to the production and use of packaging.

If you need more information on polyethylene products and services we offer, please do not hesitate to contact us!

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