Manufacturers and plastic end-users are creating sustainability stories and environmental initiatives to reduce plastic waste and the use of virgin resins and polymers. Across many industries, manufacturers and users of plastic materials are switching to recyclable plastic films and parts. This is occurring across several industries and end markets, including automotive, packaging, and consumer plastic products.
Why use recycled plastic?
Plastic waste and chemical pollutants are raising many environmental concerns and threats to aquatic life, wildlife, and humans. Sustainability is also one of the main drivers to increase the use of plastic recycling and decrease the use of non-recyclable plastic materials. Reducing plastic waste through recycling provides the following:
Lowers the waste sent to landfills
Reduces carbon footprint
Lowers energy needed to produce more plastics
Complies with the evolving environmental regulatory restrictions involving single-use plastics and plastic waste
Lowers the overall cost of plastics parts through the use of less expensive reused materials or by the utilization of plastic scrap back into production cycles
This pushes plastic compounders to develop their manufacturing processes and find solutions for the typical performance issues faced with the recycling and compounding of plastic materials. The main types of recycled materials are post-consumer and post-industrial plastic resins, depending on the source of the plastic waste and processability. This includes polyolefins, polyamides, PVC, PET, and various other thermoplastic materials.
A wide range of polymer additives is used in masterbatches and plastic recycling processes to enable the re-use of flexible and rigid plastics and to recycle scrap and waste produced from the plastic manufacturing processes.
Recycling Methods by Resin Type:
Before we get to the recycling and compounding solutions, let's explore the sources of plastic waste, recyclability, and common challenges faced by the plastic recycling industry:
1. Post-Consumer Resins:
These are recyclable plastic materials that are sourced from consumer products waste, from carpeting waste to packaging plastics. PCR can be FDA compliant and commonly used on its own or in conjunction with virgin resins in various applications depending on the level of sorting and cleaning.
Common challenges faced with the processing of post-consumer plastics (PCR):
In recycling processing, multiple types of polymer types, fillers, and other ingredients are mixed in the production stream due to the application or sorting process. For that reason, compatibilization is a necessity for compounders to achieve the mechanical properties and desired specifications.
Since there is so much variability from lot to lot with the recycling of PCR base resin, a compounder must be able to respond instantly to the changing specs. Compounders must be able to respond to the changing specs by developing robust formulations that meet the broad specs of recycled plastic materials. This requires using a variety of plastic additives including, antioxidants, heat stabilizers, UV stabilizers, impact modifiers, processing aids, and more.
Maintaining the melt stability of recycled materials is more challenging than virgin polymers. Therefore, compounders optimize their processes and utilize additives to increase melt stability, reduce scrap, and limit plastic waste.
2. Post-Industrial Resins:
This type of recyclable material is made from recycling the scrap off production streams. PIRs are preferred over PCRs as they have a tighter spec range and are completely traceable; in other words, you know precisely the plastic types in the lot. However, this is still more challenging to process compared to virgin materials. Therefore, in-house recycling is also a way to control the specs by re-introducing scrap into production steams at a certain percentage of the formulation. Although recycling of post-industrial resins is more controlled, there are several challenges faced with the processing of PIRs:
When trying to create specific colors or shades using recycled plastics, excluding black, color shifts are significant and difficult to control.
Recycled industrial plastics have been through multiple heat cycles from the initial creation of the material, several production cycles, including extrusion and pelletizing, to the heat cycle for creating the new compound. Plastic additives, anti-oxidants, polymer modifiers, and chemical additives are used to improve stability throughout the recycling process. The recycling here will be an additional heat cycle that requires heat stability to prevent the deterioration of physical and mechanical properties in the produced plastic parts.
Compounders face other challenges depending on the desired specs of the end-use application, including melt stability, gas fading, impact resistance, weatherability, stiffness, and mechanical strength.
Plastic Recycling Materials by Application:
SI Group Recommended Solutions for Recycled Plastics:
Explore our recommended specialty polymer and plastic additives from SI Group for use in recycling streams and plastics. Find the suitable product by polymer or plastic-type and by application:
Many other plastics additives are used to compound and reuse plastic polymers, such as plasticizers, internal lubricants, impact modifiers, flame retardants, anti-static additives, etc.
You can click below to explore our range of plastic additives from the SI Group. Find your solution by application and polymer type. Specialists are available for assistance and product recommendations.
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