Before we can begin to apply recycled plastics, we need to understand how their properties can differ from ‘virgin’ plastics. As designers and engineers are often unfamiliar with recycled plastics, this can cause uncertainties about the materials, where and when to apply them and how they will behave during production. In the video below, Ruud Balkenende, Professor of Circular Product Design at Delft University of Technology, explains the properties of recycled plastics and how they can be improved.

Main Takeaways

• The properties of recycled plastics are improved through compounding: i.e. blending in additives or virgin polymers.
• Recycled plastics are likely to contain legacy additives and contaminants that affect the material’s quality. The material will also have degraded during previous use and processing.
• Recycling affects a plastic’s mechanical properties (e.g. density, tensile strength, elasticity, brittleness and viscosity) and aesthetic properties (e.g. colour, odour, surface finish).
• These properties can be improved by blending in fillers and additives such as thermal stabilisers, UV absorbers and impact modifiers.
• Yet additives may themselves make the material more difficult to recycle in the future. Therefore, try to limit their use whenever possible.