Processing and design considerations when using recycled material in plastics-based applications.
Recycling of polymers has become increasingly important to reduce waste and preserve the environment. However, the processing of recycled polymers poses several challenges that must be overcome to achieve high-quality products. On this page, we will share some of the major challenges of processing recycled polymers.
One of the biggest challenges of processing recycled polymers is the presence of contaminants, such as dirt, grease, and other materials that can affect the quality of the material. Contaminants can cause processing problems, such as reduced flowability and increased melt viscosity, which can lead to lower production efficiency and product quality.
Recycled polymers can become contaminated through exposure to the environment, during transportation/storage and during the recycling process itself.
The presence of contaminants can also affect the physical and mechanical properties of recycled polymers, making them less suitable for certain applications. For example, contaminants can cause variations in colour, density, and tensile strength, which can negatively impact the performance of the final product.
Contamination is a challenge in the processing of recycled polymers, but it can often be partially or fully overcome with careful attention to detail, the use of appropriate processing techniques, and a robust quality control program. For further advice, please contact our technical team.
Viscosity changes are a common issue in recycled polymers. These changes can occur due to molecular degradation, which is caused by exposure to high temperatures, sunlight, and other environmental factors. This can result in reduced flowability, increased melting temperature, and reduced product quality, making it difficult to process recycled plastics effectively.
Viscosity changes can also affect the mechanical properties of recycled polymers, such as tensile strength and elongation, which can make them less suitable for certain applications. This can result in the need for additional processing steps, such as blending with virgin material to achieve the desired properties.
To overcome the challenge of viscosity changes in recycled polymers, it is important to implement appropriate processing techniques. This can involve the use of specialized equipment, such as twin-screw extruders and melt pumps, to improve the flowability of the recycled material. Additionally, the use of processing aids, such as viscosity-enhancing additives, can help to improve the processing properties of recycled polymers and reduce the impact of viscosity changes.
Flammability is a significant concern when processing recycled materials, particularly in the case of certain types of polymers. The flammable nature of these materials can pose a fire hazard during processing, requiring specialised processing methods and equipment to ensure safety.
To overcome the challenge of flammability in recycled polymers, it is important to implement appropriate processing techniques and equipment. This can involve the use of fire-resistant additives, such as flame retardants. Additionally, the use of specialized processing equipment, such as flame-resistant extruders, can help to reduce the risk of fire and improve processing efficiency.
Colour variation is common in the processing of recycled polymers. This is because recycled polymers can be made from a variety of different sources, each with its own unique colour. As a result, recycled polymers can exhibit a wide range of colour variation, which can make it difficult to produce consistent and uniform products.
In addition to being aesthetically unappealing, colour variation can also impact the performance of recycled polymers in certain applications, particularly those where appearance is critical, such as in packaging and consumer goods. This can result in the need for additional processing steps, such as blending with virgin polymers or colouring agents, to achieve the desired result.
To overcome the challenge of colour variation in recycled polymers, it is important to implement appropriate processing techniques and to implement strict quality control measures. This can involve sourcing material producers that use sorting and cleaning techniques to separate recycled materials by colour, as well as the use of specialized processing equipment, such as colour-sorting machines, to achieve the desired level of consistency.
Recycled polymers are a fantastic solution for many applications. Examples of successful implementations include:
- Packaging products: Plastic bags, containers, and bottles, reducing the need for virgin materials and promoting sustainability.
- Building and construction: Recycled polymers can be used to produce building materials, such as roof tiles, decking, and fencing, which are durable, weather-resistant, and long-lasting.
- Consumer goods: Recycled polymers can be used to produce a variety of consumer goods, such as toys, household items, and sporting equipment, reducing the need for virgin materials and promoting sustainability.
- Transportation: Recycled polymers can be used to produce lightweight and durable parts for the transportation industry, such as vehicle interiors and exteriors, reducing the need for virgin materials and promoting sustainability.
- Agricultural products: Recycled polymers can be used to produce a variety of agricultural products, such as irrigation tubing, seed trays, and mulch film, reducing the need for virgin materials and promoting sustainability.
There are several use cases where they may not be appropriate or additional factors will need to be considered, including medical applications, food packaging and high-performance applications. It is important to carefully evaluate the suitability of recycled polymers for each individual application to ensure that they meet the necessary requirements and standards.
Below we have provided some examples of applications where recycled polymers may not be suitable, or where extra considerations will need to be made:
- Medical applications: Medical devices and implants that come into contact with the human body require high levels of purity and consistent physical properties, which can be difficult to achieve with recycled polymers.
- Food packaging: Food packaging materials must meet strict safety regulations and must not release harmful substances into food. Recycled polymers may contain contaminants that could leach into food, making them unsuitable for use in food packaging.
- High-performance applications: Recycled polymers may have reduced physical properties compared to virgin polymers, making them unsuitable for use in high-performance applications where strength and durability are critical, such as in aircraft and automotive parts.
- Applications where colour consistency is critical: Certain applications, such as packaging and consumer goods, require consistent and uniform colours. The wide range of colours that can be found in recycled polymers can make it difficult to achieve the desired level of colour consistency in these applications.
The processing of recycled polymers is challenging, but many of these issues can be overcome with careful attention to detail, the use of appropriate processing techniques, and a robust quality control program. By processing recycled polymers, we can reduce waste, conserve resources, and help preserve the environment for future generations.