Polyethylene for rotomoulding
Polyethylene for rotomoulding is a lightweight and strong material, making it suitable for a wide range of applications. It is a thermoplastic polymer, which means it can be repeatedly melted and reshaped. Polyethylene is one of the most widely used plastics in the world and is available in a variety of types, including linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE).
Polyethylene has excellent chemical resistance. It is resistant to most chemicals, including acids, bases, and organic solvents. We manufacture a wide range of containers for storage, handling and transport of chemicals and tanks for diesel fuel and hydraulic oil. Polyethylene products typically also perform well at lower temperatures: at temperatures as low as -40 °C it still shows its flexibility, resulting in products that are resistant to cold impact.
LLDPE and HDPE
LLDPE and HDPE are the types of polyethylene that are commonly used in rotomoulding. Linear low-density polyethylene (LLDPE) is often selected: it has more stiffness compared to LDPE and still is very tough and impact resistant. It is used for products such as fuel tanks, technical parts, and agricultural products. High-density polyethylene (HDPE) is the stiffest type of PE. It also is very durable and impact-resistant and used to make products such as storage tanks, and fish tubs.
Melt flow rate
The melt flow rate (MFR) of polyethylene is an important property to consider when selecting the right polyethylene resin for a product. It is not linked to the density but directly related to the viscosity of the polymer melt and therefore has a significant impact on the processing and final properties of the product.
A high melt flow rate indicates that the polymer has a low viscosity and will flow easily, making it suitable for fine details in the mould and thin-walled applications. On the other hand, a low melt flow rate indicates that the polymer has a high viscosity and will not flow as easily, making it more suitable for thicker-walled applications. This means that the polymer will not flow as easily, resulting in a more uniform wall in thicker products.
MFR also has an effect on the final properties of the product. Selecting the appropriate melt flow rate of polyethylene is crucial as it can affect the strength, chemical resistance, and surface finish of the final product. It’s important to take into account all the properties required for the product when making this decision.
Crosslinked polyethylene creates bonds
Crosslinked polyethylene creates bonds, it is a special version of PE and abbreviated XPE. Crosslinking PE further increases the already excellent strength and chemical resistance. Crosslinking is a process creating chemical bonds between its polymer chains. This improves the material’s resistance to heat, chemicals, and stress, making it suitable for use in high-performance applications. A disadvantage of crosslinked PE is its limited recyclability: the bonds between the polymer chains hinder melting.
PE foam creates sandwich constructions
The rotomoulding process allows us to manufacture products with two PE skins filled with a PE foam core. This skin-foam-skin build-up creates a sandwich construction and enhances product stiffness whilst keeping weight low. The PE outer layers and the PE foam core form one unified construction: the layers cannot be separated. It’s ideal to create large open containers like fish tubs. And because this multi-layered construction is made from layers of the same polyethylene material it still is recyclable.
Polyethylene: popular for rotomoulding
Polyethylene is a popular material for rotomoulding due to its resistance and strength, but it does have limitations. PE is prone to creep, which means it can deform over time under loads. This can affect its dimensional stability and reduce the strength of a product under continuous load. PE has a limited heat resistance, which means it may soften when exposed to high temperatures. PE is not suitable for high-pressure applications such as pipes for gas distribution or fluid transportation, or for pressure vessels.
While PE has many advantages, it is important to keep in mind these limitations and choose the right grade of polyethylene for the specific application and use. Overall, polyethylene is a versatile material that is often used in rotomoulding to create a wide range of products.