Challenges Around Recycled Polypropylene

Plastic Recycling

Challenges Around Recycled Polypropylene

Milliken Chemical

Overcoming the Challenges in Maximizing the Usage of Recycled Polypropylene

What are the Challenges of Polypropylene Recycling?



Recycled PP Exhibits Different Characteristics Compared to Virgin PP

Properties of recycled PP (rPP) may differ from those of virgin PP, such as melt-flow rate (MFR), molecular weight, or thermal stability


This can limit the use of recycled PP in applications where impact performance and part stability are critical, such as in automotive or durable goods.


To achieve performance similar to virgin PP, polypropylene recyclers can use additives specifically designed for use in recycled PP. These additives can improve the properties of the recycled PP and compensate for any loss of performance or functionality caused by the recycling process.


Our team of experts helps recyclers expand application use of rPP with innovative additive technology that does not sacrifice performance.  Helping brand owners achieve their sustainability goals of increased recycled content use.


Milliken’s DeltaMax performance modifiers are intended to increase melt flow rate and maintain or improve impact performance of rPP.


By creating a base resin with improved impact and melt flow rate properties, DeltaMax enables more recycled content to be added to a PP blend without compromising overall performance, while allowing converters to save energy by running machines with faster cycle times or by processing at lower temperatures and/or pressures.



This inconsistency negatively affects the efficiency of the polypropylene recycling process and the quality of the recycled plastics.

The inconsistency of post-consumer plastic waste creates one of the biggest challenges for plastic recyclers.  Plastic recyclers use (post-consumer and/or post-industrial) waste as their raw material. The quality of plastic waste can vary based on the type of plastic, the source of the waste, and the handling practices during collection and transport.


To enhance consistency, plastic recyclers often characterize incoming waste streams, create ways to mix large amounts of waste streams to increase homogeneity, and use quality control systems to ensure recycled PP is in specifications.  But these solutions can result in significant additional costs. 


Our team understands this challenge and applies their deep understanding of polypropylene (PP) resin characteristics and end user applications to create more consistent quality solutions.


Milliken Viscosity Modifiers Portfolio


Many times, the MFR of the incoming waste is not where it should be for the intended end-use application. In these cases, viscosity modifiers are required to upgrade the quality of the recycled PP. When the MFR of the incoming waste fluctuates, it can be very challenging for the operators to add the right amount of viscosity modifier to ensure the desired melt flow rate specification is reached. The viscosity modifier needs to be very consistent in its formulation and delivery form. Milliken’s Viscosity Modifiers (MVM) have these qualities. We ensure the right amount of active ingredient is added to each product/grade, our product form is uniform and consistent, enabling exact addition / reducing surprises for the recycling operator. 


MVM is a solid concentrate designed for recyclers to increase the melt flow rate of post-consumer and post-industrial recycled polypropylene (rPP). It achieves this by shortening the material’s average molecular chain length, resulting in an easier, more consistent flow, while allowing for precise dosing and dust-free handling.


Milliken’s Viscosity Modifiers recycled PP resins have improved properties for use in a wider range of applications. These rPP resins allow for lower processing temperatures, which can reduce cycle times and boost productivity. MVM are available in various concentrations.  


image of MVM recycled PP showing consistent quality



Recycled PP comes with more challenges than virgin PP.  Milliken concentrates help overcome these challenges by improving the properties of rPP as well as the efficiency of the polypropylene recycling process providing higher quality recycled plastics.  With Milliken concentrates recyclers can increase use of recycled resins, creating more recyclable products, and helping to close the circularity loop.


For more information on Milliken’s Viscosity Modifiers, DeltaMax, or help with maximizing the usage of recycled polypropylene contact us.