Pieter Billen

Tenure track docent

Research themes










With a general interest in circular materials, my research focuses on systems innovation and on both end-of-life (EoL) chemical recycling and production of advanced biobased materials. 

Focus 1: Circular Systems Innovation (Early stage sustainability assessment and optimization)

The more material cycles are technologically feasible, the more complex choices for sustainable solutions have become. From an engineering perspective, I took up the challenge to integrate various state-of-the-art sustainability assessment methods (LCA, TEA, and other) into a design methodology that can be applied to (bio)-chemical process and systems innovation. Well aware that no environmental benefit is achieved without actual operations and investments, such integrated approach is necessary to seek systems with combined environmental benefit and sufficient economic return. 

Focus 2: Chemical and Biochemical Recycling (of Plastics)

As the EU recycling targets are increasing to 55% in 2025, it is our vision that we are hitting the limits of technological capabilities, if industry is applying mechanical recycling (sorting/cleaning/extrusion). Therefore, our group is developing (thermo)chemical recycling technologies for polycondensates (both thermoplasts and thermosets) as well as for polyolefins. 

Currently our main target is a full chemical recycling scheme for polyurethanes, by means of alcoholysis (picture on the right). Thus far, we were able to recover high-purity polyols, and have indications that complete recycling of residual fraction is possible. 

Additionally, we are currently upgrading pyrolytic oils from plastic feedstock to valuable materials, using expertise built in oleochemical material synthesis.

glycolyzed polyurethane


Chemical recycling of polyurethanes: dual (alternatively triple) phase alcoholysis 




Focus 3: Advanced Biomaterials (Oleochemical Building Blocks)

I collaborate with colleagues Lukasz Pazdur and Serge Tavernier, to exploit the functionalities in oleochemical building blocks ([un]saturated free fatty acids) to produce renewable and highly versatile materials. Such materials can be biodegradable, hydrophobic polymers, but also grafting agents, and tensio-active molecules.