What is Polyethylen (PE) ?

polyethylene chains

Polyethylene (PE) is one of the most widely used plastics in the world and belongs to the group of polyolefins. It is produced by the polymerization of ethylene (ethene) and is used in an enormous variety of products and industrial applications.

Polyethylene can be found in everyday products such as bottles, containers, films, bags, pipes and protective packaging. It is particularly important in the packaging industry because it combines low weight, flexibility, toughness, moisture resistance and good chemical resistance.

PE is also well suited to film production, including blown-film extrusion, which makes it an important material for the manufacture of flexible packaging, bags, tubing and industrial films.

At Polymer Synthese Werk, polyethylene is one of the key materials used for the production of customized films, bags and tubing.

Polyethylene as a Polyolefin

Polyethylene is a semi-crystalline, non-polar thermoplastic. Its properties depend strongly on the molecular structure, degree of branching, molecular weight and density of the polymer chains.

During polymerization, polyethylene can be produced in different grades with different structures and material properties. These differences have a direct influence on characteristics such as:

  • Density

  • Flexibility

  • Tensile strength

  • Stiffness

  • Impact resistance

  • Transparency

  • Chemical resistance

  • Permeability

  • Processing behavior

  • Temperature resistance

This broad range of properties is one of the reasons why polyethylene is used for such a wide variety of applications.

The Main Types of Polyethylene

Depending on density, molecular structure and molecular weight, polyethylene is available in several different grades.

PE-HD / HDPE – High-Density Polyethylene

HDPE (High-Density Polyethylene) typically has a density of approximately 0.94–0.97 g/cm³.

The polymer chains are comparatively linear and have relatively little branching. This results in a more tightly packed molecular structure and generally provides higher stiffness, strength and density than low-density polyethylene.

HDPE is used for a wide range of applications, including:

  • Bottles and containers

  • Pipes

  • Industrial components

  • Packaging

  • Caps and closures

  • Technical products

Its good chemical resistance and mechanical properties make HDPE suitable for demanding applications.

PE-MD / MDPE – Medium-Density Polyethylene

MDPE (Medium-Density Polyethylene) has properties between those of HDPE and LDPE.

Its molecular structure and density provide a balance between flexibility, toughness and mechanical strength.

MDPE can therefore be used where a combination of flexibility and durability is required. Depending on the formulation and application, it is suitable for films, packaging products, pipes and various industrial applications.

PE-LD / LDPE – Low-Density Polyethylene

LDPE (Low-Density Polyethylene) typically has a density of approximately 0.915–0.935 g/cm³.

Compared with HDPE, LDPE has a more highly branched molecular structure. The branches prevent the polymer chains from packing as closely together, resulting in a lower density and a more flexible material.

LDPE is particularly important for flexible packaging applications.

Typical applications include:

  • Packaging films

  • Plastic bags

  • Waste bags

  • Tubing

  • Protective covers

  • Industrial packaging

  • Flexible films

LDPE offers a combination of flexibility, toughness, moisture resistance and good processability, making it one of the most important materials for flexible plastic packaging.

PE-LLD / LLDPE – Linear Low-Density Polyethylene

LLDPE (Linear Low-Density Polyethylene) has a predominantly linear molecular structure with short branches.

It combines many of the advantages of LDPE with high tensile strength, good puncture resistance and good flexibility.

LLDPE is widely used for:

  • Stretch films

  • Packaging films

  • Industrial films

  • Bags

  • Agricultural films

  • Protective films

LLDPE is particularly useful where flexibility and mechanical strength are required simultaneously.

High-Molecular-Weight Polyethylene

In addition to polyethylene grades primarily differentiated by density, there are polyethylene types with particularly high molecular weights.

PE-HMW – High-Molecular-Weight Polyethylene

PE-HMW (High-Molecular-Weight Polyethylene) has a significantly higher molecular mass than conventional polyethylene grades.

The longer polymer chains can provide improved mechanical properties and wear resistance. Depending on the specific grade, PE-HMW is used for technical components and demanding industrial applications.

PE-UHMW – Ultra-High-Molecular-Weight Polyethylene

PE-UHMW (Ultra-High-Molecular-Weight Polyethylene) has an extremely high molecular weight, which can reach several million grams per mole depending on the grade.

Its exceptionally long polymer chains provide outstanding properties such as:

  • Very high wear resistance

  • Excellent abrasion resistance

  • High impact strength

  • Low coefficient of friction

  • Excellent chemical resistance

UHMWPE is therefore used primarily in specialized technical applications rather than conventional packaging.

Processing of Polyethylene

Polyethylene can be processed using a variety of manufacturing techniques.

Two particularly important processes are:

Injection Moulding

Injection moulding is widely used to manufacture solid plastic components such as containers, closures, technical parts and other moulded products.

Blown-Film Extrusion

Blown-film extrusion is particularly important for flexible packaging.

In this process, molten polyethylene is extruded through a circular die to form a thin tube. The tube is inflated with air and cooled before being collapsed and processed into film.

This technology makes it possible to manufacture polyethylene films in a wide range of:

  • Widths

  • Thicknesses

  • Lengths

  • Colors

  • Surface properties

  • Technical specifications

Blown-film extrusion is therefore a key production process for the manufacture of plastic bags, packaging films and tubing.

Appearance and Material Properties

In its natural, unpigmented form, polyethylene is generally translucent to milky-white and has a characteristic wax-like surface feel.

Its exact appearance depends on the grade, processing conditions, thickness and additives used.

Polyethylene can also be modified with pigments and functional additives to achieve specific optical and technical properties.

Depending on the application, PE films can be manufactured as:

  • Transparent

  • Translucent

  • Opaque

  • Colored

Temperature Resistance

The usable temperature range of polyethylene depends strongly on the specific grade and application.

Typical maximum continuous-use temperatures are approximately 75 °C for LDPE and up to around 95 °C for HDPE, although actual performance depends on the material grade, mechanical load, exposure time and environmental conditions.

Polyethylene is therefore suitable for many everyday and industrial applications, but it is not generally intended for continuous exposure to high temperatures.

At low temperatures, PE generally retains good impact properties, although its behavior can vary depending on the grade and application.

UV Resistance and Outdoor Applications

Unmodified polyethylene can be affected by prolonged exposure to ultraviolet radiation.

UV exposure can cause gradual degradation of the polymer and may lead to changes in mechanical properties, discoloration or embrittlement over time.

For outdoor applications, polyethylene can therefore be stabilized with suitable additives.

Carbon black, for example, is widely used in certain PE products to provide effective UV protection. Other UV stabilizer systems may also be used depending on the required application and product specification.

This makes appropriately stabilized polyethylene suitable for a variety of outdoor applications.

Electrical Properties

Polyethylene has excellent electrical insulating properties.

This makes PE suitable for applications where electrical insulation and low electrical conductivity are required.

At the same time, standard polyethylene can accumulate electrostatic charges. Where this is undesirable, the material can be modified with suitable antistatic or electrically dissipative additives.

Such properties can be particularly important in industrial and technical packaging applications.

Chemical Resistance

One of the major advantages of polyethylene is its good resistance to many chemicals.

Depending on the grade and operating conditions, PE is resistant to many substances including:

  • Oils

  • Alcohols

  • Alkalis

  • Diluted acids

  • Many aqueous solutions

However, chemical resistance always depends on factors such as concentration, temperature, exposure time and the specific polyethylene grade.

For critical applications, the compatibility of the selected material should therefore be assessed individually.

Water Resistance and Moisture Barrier

Polyethylene is hydrophobic and has very low water absorption.

This makes PE particularly suitable for applications where protection against moisture and water is required.

The material's water resistance is one of the reasons why polyethylene films and packaging are widely used for:

  • Moisture-sensitive products

  • Outdoor applications

  • Protective packaging

  • Industrial goods

  • Agricultural applications

  • Transport and storage

Gas and Aroma Permeability

Although polyethylene provides an effective barrier against liquid water, it is comparatively permeable to gases and certain aromas when compared with high-barrier plastics.

For applications requiring a high barrier against oxygen, water vapor, aromas or other gases, polyethylene may therefore be combined with other materials.

This is one area where composite and multilayer films can offer significant advantages.

By combining different polymers or barrier layers, packaging can be designed to provide a broader range of protective properties while maintaining the processing and mechanical characteristics required for the application.

Polyethylene in Packaging

PE is one of the most important materials in the flexible packaging industry.

Its combination of flexibility, toughness, low weight, moisture resistance and good processability makes it suitable for a wide range of packaging products.

Polyethylene can be used to manufacture:

  • Packaging films

  • Plastic bags

  • Waste bags

  • Industrial bags

  • Tubing

  • Protective covers

  • Shrink films

  • Stretch films

  • Agricultural films

  • Industrial packaging

At Polymer Synthese Werk, we use our experience in polyethylene processing to manufacture customizedfilms, bags and tubingfor industrial and commercial customers.

Polyethylene and Recycling

Polyethylene is a thermoplastic and can be mechanically recycled when suitable collection and recycling systems are available.

PE packaging is commonly identified by recycling codes such as 2 for HDPE and 4 for LDPE.

The recyclability of a specific packaging product depends, among other factors, on its material composition, additives, colors, contamination and the recycling infrastructure available.

For this reason, packaging design and material selection play an important role in developing recyclable packaging solutions.

Where appropriate, mono-material PE solutions can provide advantages for recycling compared with packaging made from incompatible material combinations.

Polyethylene for Outdoor Applications

The combination of low water absorption, moisture resistance, toughness and relatively low weight makes polyethylene suitable for many outdoor applications.

Depending on the grade and stabilization system, PE can be used for applications such as:

  • Agricultural films

  • Silage films

  • Construction films

  • Protective covers

  • Tarpaulins

  • Outdoor packaging

  • Pipes and technical products

For long-term outdoor exposure, the material should be appropriately stabilized against UV radiation.

Why Polyethylene Is So Versatile

The success of polyethylene is largely due to its ability to provide a broad range of material properties at comparatively low weight and cost.

Depending on the grade and formulation, PE can be:

  • Flexible or relatively rigid

  • Transparent or opaque

  • Soft or mechanically robust

  • Lightweight

  • Moisture resistant

  • Chemically resistant

  • Electrically insulating

  • Recyclable

  • Easy to process

This versatility makes polyethylene one of the most important materials for modern packaging and industrial applications.

Our Expertise in Polyethylene Films and Packaging

At Polymer Synthese Werk, we have many years of experience in processing polyolefins and manufacturing customized packaging solutions.

We produce PE films, bags and tubing for a wide range of applications and can adapt products to individual customer requirements.

Depending on the application, we can provide solutions with different:

  • Materials

  • Dimensions

  • Thicknesses

  • Surface properties

  • Colors

  • Optical characteristics

  • Technical additives

  • Functional properties

Our goal is to combine the material properties of polyethylene with a product design that meets the specific requirements of your application.

Need the Right PE Solution for Your Application?

Whether you require LDPE, MDPE, HDPE, LLDPE or a customized PE film, our team can help you select and develop the right packaging solution.

Contact us to discuss your application, material requirements and individual packaging specifications.

Other properties:

Water Vapor Permeability PE

Oxygen Permeability PE

Material Restistance LDPE

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